Search

Aims: Ischemic stroke is a major cause of disability and mortality worldwide. Transcranial direct current stimulation (tDCS) and isoflurane (ISO) preconditioning exhibit neuroprotective properties. However, it remains unclear whether tDCS enhances the protective effect of ISO preconditioning on ischemic stroke, and the underlying mechanisms are yet to be clarified., Method: A model of middle cerebral artery occlusion (MCAO), a rat ischemia-reperfusion (I/R) injury model, and an in vitro oxygen-glucose deprivation/re-oxygenation (O/R) model of ischemic injury were developed. ISO preconditioning and tDCS were administered daily for 7 days before MCAO modeling. Triphenyltetrazolium chloride staining, modified neurological severity score, and hanging-wire test were conducted to assess infarct volume and neurological outcomes. Untargeted metabolomic experiments, adeno-associated virus, lentiviral vectors, and small interfering RNA techniques were used to explore the underlying mechanisms., Results: tDCS/DCS enhanced the protective effects of ISO pretreatment on I/R injury-induced brain damage. This was evidenced by reduced infarct volume and improved neurological outcomes in rats with MCAO, as well as decreased cortical neuronal death after O/R injury. Untargeted metabolomic experiments identified oxidative phosphorylation (OXPHOS) as a critical pathological process for ISO-mediated neuroprotection from I/R injury. The combination of tDCS/DCS with ISO preconditioning significantly inhibited I/R injury-induced OXPHOS. Mechanistically, Akirin2, a small nuclear protein that regulates cell proliferation and differentiation, was found to decrease in the cortex of rats with MCAO and in cortical primary neurons subjected to O/R injury. Akirin2 functions upstream of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). tDCS/DCS was able to further upregulate Akirin2 levels and activate the Akirin2/PTEN signaling pathway in vivo and in vitro, compared with ISO pretreatment alone, thereby contributing to the improvement of cerebral I/R injury., Conclusion: tDCS treatment enhances the neuroprotective effects of ISO preconditioning on ischemic stroke by inhibiting oxidative stress and activating Akirin2-PTEN signaling pathway, highlighting potential of combination therapy in ischemic stroke., (© 2024 The Author(s). CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Aims: Incidence of acute mountain sickness (AMS) ranges from 40%-90%, with high-altitude cerebral edema (HACE) representing a life-threatening end stage of severe AMS. However, practical and convenient preventive strategies for HACE are lacking. Remote ischemic preconditioning (RIPC) has demonstrated preventive effects on ischemia- or hypoxia-induced cardiovascular and cerebrovascular diseases. This study aimed to investigate the potential molecular mechanism of HACE and the application of RIPC in preventing HACE onset., Methods: A hypobaric hypoxia chamber was used to simulate a high-altitude environment of 7000 meters. Metabolomics and metabolic flux analysis were employed to assay metabolite levels. Transcriptomics and quantitative real-time PCR (q-PCR) were used to investigate gene expression levels. Immunofluorescence staining was performed on neurons to label cellular proteins. The fluorescent probes Mito-Dendra2, iATPSnFR1.0, and CMTMRos were used to observe mitochondria, ATP, and membrane potential in cultured neurons, respectively. TUNEL staining was performed to detect and quantify apoptotic cell death. Hematoxylin and eosin (H&E) staining was utilized to analyze pathological changes, such as tissue swelling in cerebral cortex samples. The Rotarod test was performed to assess motor coordination and balance in rats. Oxygen-glucose deprivation (OGD) of cultured cells was employed as an in vitro model to simulate the hypoxia and hypoglycemia induced by RIPC in animal experiments., Results: We revealed a causative perturbation of glucose metabolism in the brain preceding cerebral edema. Ischemic preconditioning treatment significantly reprograms glucose metabolism, ameliorating cell apoptosis and hypoxia-induced energy deprivation. Notably, ischemic preconditioning improves mitochondrial membrane potential and ATP production through enhanced glucose-coupled mitochondrial metabolism. In vivo studies confirm that RIPC alleviates cerebral edema, reduces cell apoptosis induced by high-altitude hypoxia, and improves motor dysfunction resulting from cerebral edema., Conclusions: Our study elucidates the metabolic basis of HACE pathogenesis. This study provides a new strategy for preventing HACE that RIPC reduces brain edema through reprogramming metabolism, highlighting the potential of targeting metabolic reprogramming for neuroprotective interventions in neurological diseases caused by ischemia or hypoxia., (© 2024 The Author(s). CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Cerebral ischemic damage is prevalent and the second highest cause of death globally across patient populations; it is as a substantial reason of morbidity and mortality. Mesenchymal stromal cells (MSCs) have garnered significant interest as a potential treatment for cerebral ischemic damage, as shown in ischemic stroke, because of their potent intrinsic features, which include self-regeneration, immunomodulation, and multi-potency. Additionally, MSCs are easily obtained, isolated, and cultured. Despite this, there are a number of obstacles that hinder the effectiveness of MSC-based treatment, such as adverse microenvironmental conditions both in vivo and in vitro. To overcome these obstacles, the naïve MSC has undergone a number of modification processes to enhance its innate therapeutic qualities. Genetic modification and preconditioning modification (with medications, growth factors, and other substances) are the two main categories into which these modification techniques can be separated. This field has advanced significantly and is still attracting attention and innovation. We examine these cutting-edge methods for preserving and even improving the natural biological functions and therapeutic potential of MSCs in relation to adhesion, migration, homing to the target site, survival, and delayed premature senescence. We address the use of genetically altered MSC in stroke-induced damage. Future strategies for improving the therapeutic result and addressing the difficulties associated with MSC modification are also discussed., (© 2024 John Wiley & Sons Ltd.)

Background and Purpose: Remote ischemic conditioning (RIC) is a remote, transient, and noninvasive procedure providing temporary ischemia and reperfusion. However, there is no comprehensive literature investigating the efficacy and safety of RIC for the treatment of acute ischemic stroke. In the present study, we performed a comprehensive meta-analysis of the available studies., Methods: MEDLINE, Embase, the Cochrane Library database (CENTRAL), and ClinicalTrials.gov were searched before Sep 7, 2022. The data were analyzed using Review Manager 5.4.1 software, Stata version 16.0 software, and R 4.2.0 software. Odds ratio (OR), mean difference (MD), and corresponding 95% CIs were pooled using fixed-effects meta-analysis., Results: We pooled 6392 patients from 17 randomized controlled trials. Chronic RIC could reduce the recurrence of ischemic stroke at the endpoints (OR 0.67, 95% CI [0.51, 0.87]). RIC could also improve the prognosis of patients at 90 days as assessed by mRS score (mRS 0-1: OR 1.29, 95% CI [1.09, 1.52]; mRS 0-2: OR 1.22, 95% CI [1.01, 1.48]) and at the endpoints assessed by NIHSS score (MD -0.99, 95% CI [-1.45, -0.53]). RIC would not cause additional adverse events such as death (p = 0.72), intracerebral hemorrhage events (p = 0.69), pneumonia (p = 0.75), and TIA (p = 0.24) but would inevitably cause RIC-related adverse events (OR 26.79, 95% CI [12.08, 59.38])., Conclusions: RIC could reduce the stroke recurrence and improve patients' prognosis. Intervention on bilateral upper limbs, 5 cycles, and a length of 50 min in each intervention might be an optimal protocol for RIC at present. RIC could be an effective therapy for patients not eligible for reperfusion therapy. RIC would not cause other adverse events except for relatively benign RIC-related adverse events., (© 2023 The Authors. CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Transient ischaemia and reperfusion in liver tissue induce hepatic ischaemia/reperfusion (I/R) tissue injury and a profound inflammatory response in vivo. Hepatic I/R can be classified into warm I/R and cold I/R and is characterized by three main types of cell death, apoptosis, necrosis and autophagy, in rodents or patients following I/R. Warm I/R is observed in patients or animal models undergoing liver resection, haemorrhagic shock, trauma, cardiac arrest or hepatic sinusoidal obstruction syndrome when vascular occlusion inhibits normal blood perfusion in liver tissue. Cold I/R is a condition that affects only patients who have undergone liver transplantation (LT) and is caused by donated liver graft preservation in a hypothermic environment prior to entering a warm reperfusion phase. Under stress conditions, autophagy plays a critical role in promoting cell survival and maintaining liver homeostasis by generating new adenosine triphosphate (ATP) and organelle components after the degradation of macromolecules and organelles in liver tissue. This role of autophagy may contribute to the protection of hepatic I/R-induced liver injury; however, a considerable amount of evidence has shown that autophagy inhibition also protects against hepatic I/R injury by inhibiting autophagic cell death under specific circumstances. In this review, we comprehensively discuss current strategies and underlying mechanisms of autophagy regulation that alleviates I/R injury after liver resection and LT. Directed autophagy regulation can maintain liver homeostasis and improve liver function in individuals undergoing warm or cold I/R. In this way, autophagy regulation can contribute to improving the prognosis of patients undergoing liver resection or LT., (© 2021 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

As the organ with the highest demand for oxygen, the brain has a poor tolerance to ischemia and hypoxia. Despite severe ischemia/hypoxia induces the occurrence and development of various central nervous system (CNS) diseases, sublethal insult may induce strong protection against subsequent fatal injuries by improving tolerance. Searching for potential measures to improve brain ischemic/hypoxic is of great significance for treatment of ischemia/hypoxia related CNS diseases. Ischemic/hypoxic preconditioning (I/HPC) refers to the approach to give the body a short period of mild ischemic/hypoxic stimulus which can significantly improve the body's tolerance to subsequent more severe ischemia/hypoxia event. It has been extensively studied and been considered as an effective therapeutic strategy in CNS diseases. Its protective mechanisms involved multiple processes, such as activation of hypoxia signaling pathways, anti-inflammation, antioxidant stress, and autophagy induction, etc. As a strategy to induce endogenous neuroprotection, I/HPC has attracted extensive attention and become one of the research frontiers and hotspots in the field of neurotherapy. In this review, we discuss the basic and clinical research progress of I/HPC on CNS diseases, and summarize its mechanisms. Furthermore, we highlight the limitations and challenges of their translation from basic research to clinical application., (© 2021 The Authors. CNS Neuroscience & Therapeutics Published by John Wiley & Sons Ltd.)

Remote ischaemic preconditioning reduces the risk of myocardial injury within 4 days of hip fracture surgery. We aimed to investigate the effect of remote ischaemic preconditioning on the incidence of major adverse cardiovascular events 1 year after hip fracture surgery. We performed a phase-2, multicentre, randomised, observer-blinded, clinical trial between February 2015 and September 2017. We studied patients aged ≥ 45 years with a hip fracture and a minimum of one cardiovascular risk factor. Patients were allocated randomly to remote ischaemic preconditioning applied just before surgery or no treatment (control group). Remote ischaemic preconditioning was performed on the upper arm with a tourniquet in four cycles of 5 min ischaemia and 5 min reperfusion. Primary outcome was the occurrence of major adverse cardiovascular events within 1 year of surgery. A total of 316 patients were allocated randomly to the remote ischaemic preconditioning group and 309 patients to the control group. Major adverse cardiovascular events occurred in 43 patients (13.6%) in the remote ischaemic preconditioning group compared with 51 patients (16.5%) in the control group (adjusted hazard ratio (95%CI) 0.83 (0.55-1.25); p = 0.37). Fewer patients in the remote ischaemic preconditioning group had a myocardial infarction (11 (3.5%) vs. 22 (7.1%); hazard ratio (95%CI) 0.48 (CI 0.23-1.00); p = 0.04). Remote ischaemic preconditioning did not reduce the occurrence of major adverse cardiovascular events within 1 year of hip fracture surgery. The effect of remote ischaemic preconditioning on clinical cardiovascular outcomes in non-cardiac surgery needs confirmation in appropriately powered randomised clinical trials., (© 2021 Association of Anaesthetists.)

New Findings: What is the central question of this study? Animal infarct studies indicate a delayed window of cardiac protection after remote ischaemic preconditioning (RIPC); however, the presence and duration of this delayed effect have not been examined in human microvasculature in vivo. What is the main finding and its importance? Cutaneous vasodilatation induced by local heating or ACh was increased significantly 24 and 48 h after a single bout of RIPC, respectively. Neither response persisted beyond ∼48 h. Sodium nitroprusside-induced cutaneous vasodilatation was not altered. These findings reveal a delayed increase in microvascular endothelial function after a single bout of RIPC., Abstract: Remote ischaemic preconditioning (RIPC) induces protective effects from ischaemia-reperfusion injury. In the myocardium and conduit vasculature, a single bout of RIPC confers delayed protection that begins 24 h afterwards and lasts for 2-3 days. However, the extent and the time line in which a single bout of RIPC affects the human microvasculature are unclear. We hypothesized that a single bout of RIPC results in a delayed increase in skin microvascular function. Sixteen healthy participants (age, 23 ± 4 years; seven males, nine females; MAP, 82 ± 7 mmHg) were recruited to measure cutaneous microvascular function immediately before a single bout of RIPC and 24, 48 and 72 h and 1 week after the bout. The RIPC consisted of four repetitions of 5 min of arm blood flow occlusion interspersed by 5 min reperfusion. Skin blood flow responses to local heating (local temperature of 42°C), ACh and sodium nitroprusside were measured by laser speckle contrast imaging and expressed as the cutaneous vascular conductance (CVC; in perfusion units per millimetre of mercury). Vasodilatation in response to local heating was increased 24 and 48 h after RIPC (ΔCVC, 1.05 ± 0.07 vs. 1.18 ± 0.07 and 1.24 ± 0.08 PU mmHg -1 , pre- vs. 24 and 48 h post-RIPC; P < 0.05). Acetylcholine-induced cutaneous vasodilatation increased significantly 48 h after RIPC (ΔCVC, 0.71 ± 0.07 vs. 0.93 ± 0.12 PU mmHg -1 , pre- vs. 48 h post-RIPC; P < 0.05) and returned to baseline thereafter. Sodium nitroprusside-mediated vasodilatation did not change. Thus, a single bout of RIPC elicited a delayed response in the microvasculature, resulting in an improvement in the endothelium-dependent cutaneous vasodilatory response that peaked ∼48 h post-RIPC., (© 2021 The Authors. Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Aims: This study investigated the safety and efficacy of remote ischemic conditioning (RIC) on ameliorating the sequelae of ischemic moyamoya disease (iMMD)., Methods: A total of 30 iMMD patients underwent long-term RIC and were followed up at 0.5, 1, and 2 years for clinical outcomes, including frequency of stroke recurrence, Patient Global Impression of Change (PGIC) scale, peak systolic velocities (PSV), and cerebral perfusion., Results: During the whole RIC treatment process, no RIC-related adverse event occurred. Only one of 30 patients suffered a onetime infarction (3.3%), and the ratios of acceptable PGIC were 88.2%, 64.3%, and 92.3% at 0.5, 1, and 2 years follow-up. Kaplan-Meier analysis showed the frequency of stroke recurrence was significantly reduced after RIC (P = .013). The frequency of TIA per week was 1.1 (0.6, 2.8) prior to RIC and 0.1 (0.0, 0.5) post-RIC (P < .01). Compared to baseline, PSV values were significantly reduced after RIC treatment (P = .002 at 0.5, P = .331 at 1, and P = .006 at 2 years). In patients undergoing perfusion studies, 75% obtained improvement on followed-up SPECT and 95% on followed-up PET maps., Conclusions: Remote ischemic conditioning may be beneficial on controlling iMMD-induced ischemic events, relieving symptoms, and improving cerebral perfusion, without incidence of complications in this case series., (© 2019 The Authors. CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Aims: Hyperbaric oxygen preconditioning (HBOP) attenuates brain edema, microglia activation, and inflammation after intracerebral hemorrhage (ICH). In this present study, we investigated the role of HBOP in ICH-induced microglia polarization and the potential involved signal pathway., Methods: Male Sprague-Dawley rats were divided into three groups: SHAM, ICH, and ICH + HBOP group. Before surgery, rats in SHAM and HBOP groups received HBO for 5 days. Rats in SHAM group received needle injection, while rats in ICH and ICH + HBOP groups received 100 μL autologous blood injection into the right basal ganglia. Rats were euthanized at 24 hours after ICH, and the brains were removed for immunohistochemistry and Western blotting. Neurological deficits and brain water content were determined., Results: Intracerebral hemorrhage induced brain edema, which was significantly lower in the HBOP group. The levels of MMP9 were also less in the HBOP group. HBO pretreatment resulted in less neuronal death and neurological deficits after ICH. Their immunoactivity and protein levels of M1 markers were downregulated, but the M2 markers were unchanged by HBOP. In addition, ICH-induced pro-inflammatory cytokine (TNF-α and IL-1β) levels and the phosphorylation of JNK and STAT1 were also lower in the HBOP rats., Conclusions: HBO pretreatment attenuated ICH-induced brain injuries and MMP9 upregulation, which may through the inhibiting of M1 polarization of microglia and inflammatory signal pathways after ICH., (© 2019 Zhejiang Hospital. CNS Neuroscience & Therapeutics Published by John Wiley & Sons Ltd.)

Background Peripheral artery disease is a major socioeconomic challenge in the diabetes mellitus community and non-surgical treatment options are limited. As remote ischemic conditioning ( RIC ) improves vascular function and attenuates ischemia-induced tissue damage, we investigated the efficacy of RIC on vascular and neuronal function in type 2 diabetes mellitus patients with peripheral artery disease. Methods and Results We enrolled 36 type 2 diabetes mellitus patients with moderately reduced toe pressure (40-70 mm Hg) in a randomized sham-controlled double-masked trial. Patients were allocated to 12 weeks once daily upper arm cuff-based treatment of either RIC treatment (4 cycles of 5-minute ischemia followed by 5-minute reperfusion) or similar sham-device treatment. Primary outcome was transcutaneous tissue oxygen tension of the instep of the feet. Secondary outcomes were aortic pulse wave velocity, toe pressure and toe-brachial index. Tertiary outcomes were markers of peripheral and autonomic nerve function. We enrolled 36 patients (83% men). Patients had a mean ( SD ) age of 70.7 years (6.8), diabetes mellitus duration of 18.4 years (8.3), HbA1c (gycated hemoglobin) of 59.7 mmol/mol (11.2). Eighty percent had peripheral symmetrical neuropathy. The mean difference in change of transcutaneous tissue oxygen tension from baseline between the RIC and sham-treated groups was -0.03 mm Hg ([95% CI -0.1; 0.04], P=0.438). RIC did not elicit any change in additional outcomes. Three patients experienced transient skin petechiae in the treated arm. Conclusions Long-term repeated remote ischemic conditioning treatment have no effect on tissue oxygenation, vascular or neuronal function in patients with type 2 diabetes mellitus and moderate peripheral artery disease. Clinical Trial Registration URL : http://www.ClinicalTrials.gov . Unique identifier: NCT02749942.

New Findings: What is the topic of this review? Remote ischaemic preconditioning (RIPC) and hypoxic preconditioning as novel therapeutic approaches for cardiac and neuroprotection. What advances does it highlight? There is improved understanding of mechanisms and signalling pathways associated with ischaemic and hypoxic preconditioning, and potential pitfalls with application of these therapies to clinical trials have been identified. Novel adaptations of preconditioning paradigms have also been developed, including intermittent hypoxia training, RIPC training and RIPC-exercise, extending their utility to chronic settings., Abstract: Myocardial infarction and stroke remain leading causes of death worldwide, despite extensive resources directed towards developing effective treatments. In this Symposium Report we highlight the potential applications of intermittent ischaemic and hypoxic conditioning protocols to combat the deleterious consequences of heart and brain ischaemia. Insights into mechanisms underlying the protective effects of intermittent hypoxia training are discussed, including the activation of hypoxia-inducible factor-1 and Nrf2 transcription factors, synthesis of antioxidant and ATP-generating enzymes, and a shift in microglia from pro- to anti-inflammatory phenotypes. Although there is little argument regarding the efficacy of remote ischaemic preconditioning (RIPC) in pre-clinical models, this strategy has not consistently translated into the clinical arena. This lack of translation may be related to the patient populations targeted thus far, and the anaesthetic regimen used in two of the major RIPC clinical trials. Additionally, we do not fully understand the mechanism through which RIPC protects the vital organs, and co-morbidities (e.g. hypercholesterolemia, diabetes) may interfere with its efficacy. Finally, novel adaptations have been made to extend RIPC to more chronic settings. One adaptation is RIPC-exercise (RIPC-X), an innovative paradigm that applies cyclical RIPC to blood flow restriction exercise (BFRE). Recent findings suggest that this novel exercise modality attenuates the exaggerated haemodynamic responses that may limit the use of conventional BFRE in some clinical settings. Collectively, intermittent ischaemic and hypoxic conditioning paradigms remain an exciting frontier for the protection against ischaemic injuries., (© 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.)

Aim: The effects of sevoflurane on microglia/macrophages, promoting or suppressing their activation, remains controversy. We aimed to determine whether sevoflurane preconditioning can protect brain via changing microglia/macrophage dynamics and phagocytosis profile after ischemia., Methods: The impact of sevoflurane preconditioning was evaluated on microglia/macrophage migration, phagocytosis and proliferation altogether from day 1 to day 7 after transient middle cerebral arterial occlusion (tMCAO) in rats., Results: Sevoflurane preconditioning was identified to accelerate microglia/macrophage migrating to and invasion in the ischemic core from day 1 to day 5 after damage. Significant accumulation of amoeboid and phagocytic microglia/macrophages was observed in sevoflurane group from day 3 to day 5 after ischemia injury. In addition, sevoflurane pretreatment also promoted the proliferation of microglia/macrophage (Iba1 + /Ki67 + ) dramatically in ischemic core on day 3 postinsult., Conclusions: Our current study has identified the impact of sevoflurane preconditioning on microglia/macrophage dynamics, including its migration, phagocytosis, and proliferation at early stage after brain ischemia and reperfusion. Sevoflurane might enhance microglia/macrophage activation and promote brain repair. These results could help to approach more relevant microglia/macrophage cell-based strategy for human stroke therapy., (© 2018 John Wiley & Sons Ltd.)

Background: Vasovagal syncope (VVS) is characterized by hypotension and bradycardia followed by lowering of cerebral blood flow. Remote limb ischemic preconditioning (RIPC) is well documented to provide cardio- and neuroprotection as well as to improve cerebral blood flow. We hypothesized that RIPC will provide protection against VVS-induced hypotension, bradycardia, and cerebral hypoperfusion. Second, because endothelial nitric oxide synthase has been reported as a mediator of cerebral blood flow control, we hypothesized that the mechanism by which RIPC primes the vasculature against VVS is via the α 1 -adrenoceptor-protein kinase Cε-endothelial nitric oxide synthase pathway., Methods and Results: We utilized sinusoidal galvanic vestibular stimulation in rats as a model of VVS. RIPC attenuated the lowerings of mean arterial pressure, heart rate, and cerebral blood flow caused by sinusoidal galvanic vestibular stimulation, as well as improving behavior during, and recovery after, stimulation. RIPC induced elevated serum norepinephrine, increased expression of brain α 1 -adrenoceptors, and reduced brain expression of norepinephrine transporter 1. Antagonizing adrenoceptors and norepinephrine transporter 1 prevented RIPC protection of cerebral perfusion during sinusoidal galvanic vestibular stimulation., Conclusions: Taken together, this study indicates that RIPC may be a potential therapy that can prevent VVS pathophysiology, decrease syncopal episodes, and reduce the injuries associated with syncopal falls. Furthermore, the α 1 -adrenoceptor-protein kinase Cε-endothelial nitric oxide synthase pathway may be a therapeutic target for regulating changes in cerebral blood flow., (© 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

Various diseases and toxic factors easily impair cellular and organic functions in mammals. Organ transplantation is used to rescue organ function, but is limited by scarce resources. Mesenchymal stem cell (MSC)-based therapy carries promising potential in regenerative medicine because of the self-renewal and multilineage potency of MSCs; however, MSCs may lose biological functions after isolation and cultivation for a long time in vitro. Moreover, after they are injected in vivo and migrate into the damaged tissues or organs, they encounter a harsh environment coupled with death signals due to the inadequate tensegrity structure between the cells and matrix. Preconditioning, genetic modification and optimization of MSC culture conditions are key strategies to improve MSC functions in vitro and in vivo, and all of these procedures will contribute to improving MSC transplantation efficacy in tissue engineering and regenerative medicine. Preconditioning with various physical, chemical and biological factors is possible to preserve the stemness of MSCs for further application in studies and clinical tests. In this review, we mainly focus on preconditioning and the corresponding mechanisms for improving MSC activities in vitro and in vivo; we provide a glimpse into the promotion of MSC-based cell therapy development for regenerative medicine. As a promising consequence, MSC transplantation can be applied for the treatment of some terminal diseases and can prolong the survival time of patients in the near future., (© 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

Background: Limb remote ischemic preconditioning (RIPC) protects against brain injury induced by stroke, but the underlying protective mechanisms remain unknown. As hypoxia inducible factor 1α (HIF-1α) is neuroprotective in stroke and mediates neuroinflammation, we tested the hypothesis that HIF-1α is a key factor of RIPC against stroke by mediating inflammation., Methods and Results: Stroke was induced by transient middle cerebral artery occlusion in rats, and RIPC was conducted in both hind limbs. The HIF-1α mRNA was examined by quantitative reverse transcription polymerase chain reaction after RIPC. In addition, inflammatory cytokines in the peripheral blood and brain were measured using the AimPlex multiplex immunoassays. Data showed that RIPC reduced the infarct size, improved neurological functions, and increased HIF-1α mRNA levels, interleukin (IL)-4, and IL-10 protein levels in the peripheral blood. Intraperitoneal injection of the HIF activator, dimethyloxaloylglycine, reduced the infarct size and inhibited interferon-γ protein levels, while promoting IL-4 and IL-10 protein levels, while decreasing interferon-γ protein levels in both the peripheral blood and ischemic brain. In addition, injection of dimethyloxaloylglycine had a synergistic effect with RIPC on reducing infarction and improving neurological functions, as well as decreasing interferon-γ in the peripheral blood and ischemic brain. In contrast, injection of the HIF inhibitor, acriflavine hydrochloride, abolished the protective effects of RIPC on infarction, and reduced IL-4 and IL-10 protein levels in both the peripheral blood and ischemic brain., Conclusions: We conclude that HIF-1α plays a key role in RIPC, likely mediated by a systemic modulation of the inflammatory response., (© 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

The purpose of this article is to perform the first pooled analysis on remote ischemic preconditioning (RIPC) used for the improvement of clinical outcomes of patients only undergoing on-pump coronary artery bypass grafting (CABG) in randomized controlled trials (RCTs). A systematic search was performed using PubMed, the Cochrane Library, and the Web of Science to identify studies that described the effect of RIPC on postoperative mortality in patients only undergoing on-pump CABG. The outcomes included postoperative mortality, postoperative morbidity (including incidence of myocardial infarction, atrial fibrillation, stroke, acute kidney injury, and renal replacement therapy), mechanical ventilation (MV), intensive care unit length of stay (ICU LOS), and hospital length of stay (HLOS). A total of 14 RCTs (2830 participants) were included. Our meta-analysis found that RIPC failed to reduce the postoperative mortality in patients only undergoing on-pump CABG compared with control individuals (odds ratio, 0.81; 95% confidence interval, [0.40, 1.64]; P = 0.55; I 2  = 25%). Moreover, there were no differences in postoperative morbidity, ICU LOS, and HLOS between the two groups. However, MV in the RIPC group was shorter than that in control individuals (standard mean difference, -0.41; 95% confidence interval, [-0.80, -0.01]; P = 0.04; I 2  = 73%). The present meta-analysis found that RIPC failed to improve most of clinical outcomes in patients only undergoing on-pump CABG; however, MV was reduced. Adequately powered trials are warranted to provide more evidence in the future., (© 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

Whether oxygen should be administered acutely during ST-segment elevation myocardial infarction is debated. Despite this controversy, the possible influence of supplementary oxygen on animal models of ischaemia-reperfusion injury or cardioprotection is rarely considered. We used an in vivo mouse model of ischaemia and reperfusion to investigate the effect of ventilation with room air versus 100% oxygen. The coronary artery of anaesthetized mice was occluded for 40 min. followed by 2-hrs reperfusion. Infarct size was measured by tetrazolium staining and expressed as a percentage of area at risk, determined using Evan's blue. Unexpectedly, infarct size in mice ventilated with 100% oxygen was significantly smaller than in those ventilated with room air (33 ± 5% versus 46 ± 3%; n = 6; P < 0.01). We tested a standard protocol of 3 × 5 min. cycles of remote ischaemic preconditioning (RIPC) and found this was unable to protect mice ventilated with 100% oxygen. RIPC protocols using 2.5- or 10-min. occlusion were similarly ineffective in mice ventilated with oxygen. Similar disparate results were obtained with direct cardiac ischaemic preconditioning. In contrast, pharmacological protection using bradykinin administered at reperfusion was effective even in mice ventilated with 100% oxygen, reducing infarct size from 33 ± 5% to 21 ± 3% (n = 4-6; P < 0.01). Laser speckle contrast imaging of blood flow and direct pO 2 measurements were made in the hindlimb, but these measurements did not correlate with protection. In conclusion, ventilation protocol can have a major influence on infarct size and ischaemic preconditioning protocols in mice., (© 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

Recent clinical studies have suggested that endothelial progenitor cells (EPCs) transplantation provides a modest benefit for treatment of the ischaemic diseases such as limb ischaemia. However, cell-based therapies have been limited by poor survival of the engrafted cells. This investigation was designed to establish optimal hypoxia preconditioning and evaluate effects of hypoxic preconditioning-induced autophagy on survival of the engrafted EPCs. Autophagy of CD34 + VEGFR-2 + EPCs isolated from rat bone marrow increased after treatment with 1% O 2 . The number of the apoptotic cells in the hypoxic cells increased significantly after autophagy was inhibited with 3-methyladenine. According to balance of autophagy and apoptosis, treatment with 1% O 2 for 2 hrs was determined as optimal preconditioning for EPC transplantation. To examine survival of the hypoxic cells, the cells were implanted into the ischaemic pouch of the abdominal wall in rats. The number of the survived cells was greater in the hypoxic group. After the cells loaded with fibrin were transplanted with intramuscular injection, blood perfusion, arteriogenesis and angiogenesis in the ischaemic hindlimb were analysed with laser Doppler-based perfusion measurement, angiogram and the density of the microvessels in histological sections, respectively. Repair of the ischaemic tissue was improved significantly in the hypoxic preconditioning group. Loading the cells with fibrin has cytoprotective effect on survival of the engrafted cells. These results suggest that activation of autophagy with hypoxic preconditioning is an optimizing strategy for EPC therapy of limb ischaemia., (© 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

New Findings: What is the central question of this study? It is suggested that remote ischemic preconditioning (RIPC) might offer protection against ischaemia-reperfusion injuries, but the utility of RIPC in high-altitude settings remains unclear. What is the main finding and its importance? We found that RIPC offers no vascular protection relative to pulmonary artery pressure or peripheral endothelial function during acute, normobaric hypoxia and at high altitude in young, healthy adults. However, peripheral chemosensitivity was heightened 24 h after RIPC at high altitude. Application of repeated short-duration bouts of ischaemia to the limbs, termed remote ischemic preconditioning (RIPC), is a novel technique that might have protective effects on vascular function during hypoxic exposures. In separate parallel-design studies, at sea level (SL; n = 16) and after 8-12 days at high altitude (HA; n = 12; White Mountain, 3800 m), participants underwent either a sham protocol or one session of four bouts of 5 min of dual-thigh-cuff occlusion with 5 min recovery. Brachial artery flow-mediated dilatation (FMD; ultrasound), pulmonary artery systolic pressure (PASP; echocardiography) and internal carotid artery (ICA) flow (ultrasound) were measured at SL in normoxia and isocapnic hypoxia (end-tidal PO2 maintained at 50 mmHg) and during normal breathing at HA. The hypoxic ventilatory response (HVR) was measured at each location. All measures at SL and HA were obtained at baseline (BL) and at 1, 24 and 48 h post-RIPC or sham. At SL, RIPC produced no changes in FMD, PASP, ICA flow, end-tidal gases or HVR in normoxia or hypoxia. At HA, although HVR increased 24 h post-RIPC compared with BL [2.05 ± 1.4 versus 3.21 ± 1.2 l min -1  (% arterial O 2 saturation) -1 , P < 0.01], there were no significant differences in FMD, PASP, ICA flow and resting end-tidal gases. Accordingly, a single session of RIPC is insufficient to evoke changes in peripheral, pulmonary and cerebral vascular function in healthy adults. Although chemosensitivity might increase after RIPC at HA, this did not confer any vascular changes. The utility of a single RIPC session seems unremarkable during acute and chronic hypoxia., (© 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.)

Aim: The aim of this article is to test the hypothesis that remote ischaemic preconditioning (RIPC) increases circulating endogenous local and systemic plasma (nitrite) during RIPC and ischaemia-reperfusion (IR) as a potential protective mechanism against ischaemia-reperfusion injury (IRI)., Methods: Six healthy male volunteers (mean age 29.5 ± 7.6 years) were randomized in a crossover study to initially receive either RIPC (4 × 5 min cycles) to the left arm, or no RIPC (control), both followed by an ischaemia-reperfusion (IR) sequence (20 min cuff inflation to 200 mmHg, 20 min reperfusion) to the right arm. The volunteers returned at least 7 days later for the alternate intervention. The primary outcome was the effect of RIPC vs. control on local and systemic plasma (nitrite)., Results: RIPC did not significantly change plasma (nitrite) in either the left or the right arm during the RIPC sequence. However, compared to control, RIPC decreased plasma (nitrite) during the subsequent IR sequence by ~26% (from 118 ± 9 to 87 ± 5 nmol l -1 ) locally in the left arm (P = 0.008) overall, with an independent effect of -58.70 nmol l -1 (95% confidence intervals -116.1 to -1.33) at 15 min reperfusion, and by ~24% (from 109 ± 9 to 83 ± 7 nmol l -1 ) systemically in the right arm (P = 0.03)., Conclusions: RIPC had no effect on plasma (nitrite) during the RIPC sequence, but instead decreased plasma (nitrite) by ~25% during IR. This would likely counteract the protective mechanisms of RIPC, and contribute to RIPC's lack of efficacy, as observed in recent clinical trials. A combined approach of RIPC with nitrite administration may be required., (© 2017 The British Pharmacological Society.)

Background: Remote ischemic conditioning (RIC) is a noninvasive therapeutic strategy that uses brief cycles of blood pressure cuff inflation and deflation to protect the myocardium against ischemia-reperfusion injury. The objective of this systematic review was to determine the impact of RIC on myocardial salvage index, infarct size, and major adverse cardiovascular events when initiated before catheterization., Methods and Results: Electronic searches of Medline, Embase, and Cochrane Central Register of Controlled Trials were conducted and reference lists were hand searched. Randomized controlled trials comparing percutaneous coronary intervention (PCI) with and without RIC for patients with ST-segment-elevation myocardial infarction were included. Two reviewers independently screened abstracts, assessed quality of the studies, and extracted data. Data were pooled using random-effects models and reported as mean differences and relative risk with 95% confidence intervals. Eleven articles (9 randomized controlled trials) were included with a total of 1220 patients (RIC+PCI=643, PCI=577). Studies with no events were excluded from meta-analysis. The myocardial salvage index was higher in the RIC+PCI group compared with the PCI group (mean difference: 0.08; 95% confidence interval, 0.02-0.14). Infarct size was reduced in the RIC+PCI group compared with the PCI group (mean difference: -2.46; 95% confidence interval, -4.66 to -0.26). Major adverse cardiovascular events were lower in the RIC+PCI group (9.5%) compared with the PCI group (17.0%; relative risk: 0.57; 95% confidence interval, 0.40-0.82)., Conclusions: RIC appears to be a promising adjunctive treatment to PCI for the prevention of reperfusion injury in patients with ST-segment-elevation myocardial infarction; however, additional high-quality research is required before a change in practice can be considered., (© 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

Ischemic tolerance (IT) has gained attention as an attractive strategy for improving stroke outcome. Recently, it was shown that signal responsible for rapid IT induction (tolerance induction factor - TIF) is transmitted via circulating blood. In this study, we have hypothesized about the role of the blood cell compartment in TIF production. We used hind-limb ischemia to generate TIF as a rapid preconditioning against transient middle cerebral artery occlusion (MCAO). The essential properties of protein synthesis inhibitors actinomycin D and cycloheximide were utilized to obtain the following results: (i) TIF is proteinaceous. Hind-limb ischemia mediates gene expression followed by translation, resulting in the production of TIF. Blocking of each of these two steps in protein synthesis resulted in rapid infarct evolution (281.5 ± 23.37 and 330.4 ± 71.8 mm 3 , respectively). (ii) Tourniquet-treated muscle is not a source of TIF. Actinomicine D injected into rat prior to tolerance induction significantly suppressed RNA synthesis in blood cells and muscle tissue. Cross-circulation of those rats (donors) with control animals (recipients) did not mediate significant infarct reduction (272.9 ± 12.45 mm 3 ), even when hind-limb ischemia was performed before MCAO in the recipient (223.2 ± 37.51 mm 3 ). (iii) Blood cells serve as a source of TIF. Preischemic transfusion of plasma-free, protein-synthesis-inactive blood cells, which were obtained from tolerant animals did not reduce infarct volume in recipients (131 ± 16.1 mm 3 ) in a range comparable with their protein-synthesis-active counterparts (17.2 ± 12 mm 3 ). We can conclude that blood cells are associated with the induction of rapid IT via production of a bioactive proteinaceous substance., (© 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Aims: Remote ischemic preconditioning (RIPC) of a limb is a clinically feasible strategy to protect against ischemia-reperfusion injury after stroke. However, the mechanism underlying RIPC remains elusive., Methods: We generated a rat model of noninvasive RIPC by four repeated cycles of brief blood flow constriction (5 min) in the hindlimbs using a tourniquet. Blood was collected 1 h after preconditioning and 3 days after brain reperfusion. The impact of RIPC on immune cell and cytokine profiles prior to and after transient middle cerebral artery occlusion (MCAO) was assessed., Results: Remote ischemic preconditioning protects against focal ischemia and preserves neurological functions 3 days after stroke. Flow cytometry analysis demonstrated that RIPC ameliorates the post-MCAO reduction of CD3(+)CD8(+) T cells and abolishes the reduction of CD3(+)/CD161a(+) NKT cells in the blood. In addition, RIPC robustly elevates the percentage of B cells in peripheral blood, thereby reversing the reduction in the B-cell population after stroke. RIPC also markedly elevates the percentage of CD43(+)/CD172a(+) noninflammatory resident monocytes, without any impact on the percentage of CD43(-)/CD172a(+) inflammatory monocytes. Finally, RIPC induces IL-6 expression and enhances the elevation of TNF-α after stroke., Conclusion: Our results reveal dramatic immune changes during RIPC-afforded neuroprotection against cerebral ischemia., (© 2015 John Wiley & Sons Ltd.)

Background and Aim of the Study: We have previously reported that the neocortex is selectively vulnerable to injury in an acute porcine model of hypothermic circulatory arrest (HCA) at 18°C. In view of recent evidence showing that pharmacologic preconditioning with a single dose of erythromycin induces tolerance against transient global cerebral ischemia in rats, we hypothesized that erythromycin would reduce the number of apoptotic neurons in the neocortex in an acute porcine model of HCA at 18°C., Methods: Fourteen piglets underwent 75 min of HCA at 18°C following pretreatment with erythromycin (25 mg/kg, IV) (n = 8) or vehicle (Normal Saline 0.9%) (n = 6), applied 12 hr before arrest. Three served as normal controls. After gradual rewarming to a temperature of 36°C, treatment animals were sacrificed and brains were perfusion-fixed and cryopreserved. Neuronal apoptosis after HCA was observed morphologically with hematoxylin and eosin staining, and characterized by in situ DNA fragmentation using terminal deoxynucleotidyl-transferase-mediated biotin-dUTP nick end-labeling (TUNEL) histochemistry., Results: Pre-ischemic conditioning with a single dose of the antibiotic erythromycin reduced neuronal apoptosis in the neocortex of the porcine brain. TUNEL-positive cells indicating DNA fragmentation and neuronal injury were significantly greater in the neocortex of animals treated with 18°C HCA (2.55 ± 1.17) compared to animals undergoing HCA after erythromycin preconditioning (1.76 ± 0.91) (p ≤ 0.001)., Conclusions: These results suggest that cerebral protection during HCA may be achieved with erythromycin pharmacological preconditioning in the porcine model., (© 2015 Wiley Periodicals, Inc.)

To investigate the effects of ischemia/reperfusion on rat submandibular glands without denervation and the possible protective effects of ischemia preconditioning on the glands that experienced ischemia/reperfusion, in-situ ischemia/reperfusion and ischemia preconditioning experimental models of submandibular glands of healthy male Wistar rats were conducted. For ischemia/reperfusion groups, the glands were subjected to 90 min of ischemia without denervation, followed by 1, 12, 24, or 72 h of reperfusion. Ischemia preconditioning was achieved by 3 min of ischemia following 3 min of reperfusion, performed three times before ischemia/reperfusion. Salivary secretion, histological changes, alterations of tight junctions, myeloperoxidase activity, cellular apoptosis, and reactive oxygen species levels were detected. In ischemia/reperfusion glands, rising acute-inflammation responses, reduced tight-junction width, and increased myeloperoxidase activity, reactive oxygen species levels, and apoptotic cell numbers were observed, along with secretory dysfunction, especially at 1 and 12 h post-reperfusion, which seemed to gradually return to normal by 72 h post-reperfusion. In contrast, ischemia preconditioning showed the potential to ameliorate the injury-stress responses caused by ischemia/reperfusion. Our study revealed that ischemia/reperfusion could cause a series of injury-stress responses and ultimately lead to hyposecretion, independently of the parasympathetic nerve supply, which might play an important role in the early-phase dysfunction of the transplanted glands. Ischemia preconditioning could protect the involved glands and improve ischemia/reperfusion-induced hyposecretion., (© 2014 Eur J Oral Sci.)

Background: Remote ischemic preconditioning (RIPC) harnesses an innate defensive mechanism that protects against inflammatory activation and ischemia-reperfusion injury, known sequelae of cardiac surgery with cardiopulmonary bypass. We sought to determine the impact of RIPC on clinical outcomes and physiological markers related to ischemia-reperfusion injury and inflammatory activation after cardiac surgery in children., Methods and Results: Overall, 299 children (aged neonate to 17 years) were randomized to receive an RIPC stimulus (inflation of a blood pressure cuff on the left thigh to 15 mm Hg above systolic for four 5-minute intervals) versus a blinded sham stimulus during induction with a standardized anesthesia protocol. Primary outcome was duration of postoperative hospital stay, with serial clinical and laboratory measurements for the first 48 postoperative hours and clinical follow-up to discharge. There were no significant baseline differences between RIPC (n=148) and sham (n=151). There were no in-hospital deaths. No significant difference in length of postoperative hospital stay was noted (sham 5.4 versus RIPC 5.6 days; difference +0.2; adjusted P=0.91), with the 95% confidence interval (-0.7 to +0.9) excluding a prespecified minimal clinically significant differences of 1 or 1.5 days. There were few significant differences in other clinical outcomes or values at time points or trends in physiological markers. Benefit was not observed in specific subgroups when explored through interactions with categories of age, sex, surgery type, Aristotle score, or first versus second half of recruitment. Adverse events were similar (sham 5%, RIPC 6%; P=0.68)., Conclusions: RIPC is not associated with important improvements in clinical outcomes and physiological markers after cardiac surgery in children., Clinical Trial Registration Url: clinicaltrials.gov. Unique identifier: NCT00650507., (© 2014 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.)

Aim: To investigate the impact of ischaemic pre-conditioning (Ipre) and post-conditioning (Ipost) on expression of nuclear factor erythroid 2-related factor 2 (Nrf2) gene and its dependent genes, haem oxygenase-1 (HO-1) and NADPH-quinone oxidoreductase-1 (NQO-1); inflammatory cytokines TNF-α, IL1β and ICAM-1; and apoptotic markers such as caspase-3 in renal ischaemia/reperfusion (I/R) injury., Methods: One hundred and fifty male Sprague Dawley rats were classified into five groups (each consisted of 30 rats): sham, control (I/R), Ipre + I/R, Ipre without I/R and Ipost + I/R. Serum creatinine and blood urea nitrogen (BUN) were measured at 2, 24 and 48 h after ischaemia. In kidney tissues, mRNA of Nrf2, HO-1, NQO-1, TNF-α, IL-1β and ICAM-1 and immunohistochemical expression of Nrf2 and caspase-3 were assessed., Results: Serum creatinine and BUN improved significantly in Pre + I/R group; however, they did not show any significant improvement in Post + I/R group. Also, Ipre-I/R group showed non-significant change in serum creatinine and BUN. The expression of Nrf2, HO-1 and NQO-1 is increased significantly in Pre + I/R and Pre - I/R groups, while the enhancement in Post + I/R group was non-significant. Moreover, the expression of proinflammatory cytokines (TNF-α, IL-1 and ICAM-1) and apoptotic (caspase-3) markers showed high significant attenuation in Pre + I/R group, but slight significant attenuation in Pre + I/R group., Conclusion: The renoprotective action of Ipre might include early activation and enhanced expression of Nrf2 gene and its dependent antioxidant genes, HO-1 and NOQ1, as endogenous adaptive renoprotective genes, as well as reduction in TNF-α, IL-1β, ICAM-1 and caspase-3., (© 2013 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)

Aims: Ischemic preconditioning (IPC) has short-term benefits for stroke patients. However, if IPC protective effect is memorial and the role of the intracellular protective protein heme oxygenase-1 (HO-1) is not known., Methods: Ischemic preconditioning and the corresponding sham control were achieved by blocking the blood flow of the left internal carotid artery for 20 min and 2 second, respectively, in rats. Both IPC and sham-operated animals were divided into three groups and treated with PBS, the HO-1 inducer hemin, and the HO-1 inhibitor Znpp. Three weeks after IPC, brain ischemia-reperfusion injury was achieved by left middle cerebral artery obstruction for 45 min followed by 24-h reperfusion., Results: 2,3,5-triphenyltetrazolium chloride staining and neurological dysfunction scoring showed IPC significantly reduced brain infarct area and improved neurological function occurred 3 weeks after IPC. Hemin treatment promoted whereas ZnPP blocked the benefits of IPC. Immunohistochemical analysis and Western blotting showed that the expression of HO-1 was higher in the border zone than in the necrotic core zone. The memorial IPC protection is independent of adenosine receptor A1R and A2aR expressions., Conclusions: We found for the first time that the protective effect of IPC can be remembered to protect brain injury occurred after acute response disappear. The results indicate that interventional treatment can achieve protective effect for future cerebral injury not only through interventional treatment itself but also through the memorial and revivable IPC, eliminating the concern that temporary ischemia caused by interventional treatment may leave harmful effect in the brain., (© 2013 John Wiley & Sons Ltd.)

Background: Our previous randomized controlled trial demonstrated cardiorespiratory protection by remote ischemic preconditioning (RIPC) in children before cardiac surgery. However, the impact of RIPC on myocardial prosurvival intracellular signaling remains unknown in cyanosis. RIPC may augment phosphorylated protein signaling in myocardium and circulating leukocytes during tetralogy of Fallot (ToF) repair., Methods and Results: Children (n=40) undergoing ToF repair were double-blind randomized to RIPC (n=11 boys, 9 girls) or control (sham RIPC: n=9 boys, 11 girls). Blood samples were taken before, immediately after, and 24 hours after cardiopulmonary bypass. Resected right ventricular outflow tract muscle and leukocytes were processed for protein expression and mitochondrial respiration. There was no difference in age (7.1 ± 3.4 versus 7.1 ± 3.4 months), weight (7.7 ± 1.8 versus 7.5 ± 1.9 kg), or bypass or aortic cross-clamp times between the groups (control versus RIPC, mean±SD). No differences were seen between the groups for an increase in the ratio of phosphorylated to total protein for protein kinase B, p38 mitogen activated protein kinase, signal transducer and activator of transcription 3, glycogen synthase kinase 3β, heat shock protein 27, Connexin43, or markers associated with promotion of necrosis (serum cardiac troponin I), apoptosis (Bax, Bcl-2), and autophagy (Parkin, Beclin-1, LC3B). A high proportion of total proteins were in phosphorylated form in control and RIPC myocardium. In leukocytes, mitochondrial respiration and assessed protein levels did not differ between groups., Conclusions: In patients with cyanotic heart disease, a high proportion of proteins are in phosphorylated form. RIPC does not further enhance phosphorylated protein signaling in myocardium or circulating leukocytes in children undergoing ToF repair., Clinical Trial Registration: URL: (http://www.anzctr.org.au/trial&#95;view.aspx?id=335613. Unique identifier: Australian New Zealand Clinical Trials Registry number ACTRN12610000496011.

Background: It is well established that acute ischemic preconditioning (IPC) protects against ischemia-reperfusion (IR) injury; however, the effectiveness of repeated IPC exposure has not been extensively investigated. We aimed to determine whether daily IPC episodes provide continued protection from IR injury in a human forearm model, and the role of cyclooxygenase-2 in these responses., Methods and Results: Thirty healthy volunteers were randomized to participate in 2 of 3 protocols (IR alone, 1-day IPC, 7-day IPC) in an operator-blinded, crossover design. Subjects in the IR alone protocol underwent flow-mediated dilation (FMD) measurements pre- and post-IR (15' upper-arm ischemia and 15' reperfusion). The 1-day IPC protocol involved FMD measurements before and after 1 episode of IPC (3 cycles of 5' upper-arm ischemia and 5' reperfusion) and IR. Day 7 of the 7-day IPC protocol was identical to the 1-day IPC protocol but was preceded by single daily episodes of IPC for 6 days prior. During each protocol, subjects received a 7-day treatment of either the cyclooxygenase-2 inhibitor celecoxib or placebo. Pre-IR FMD was similar between groups. IR alone reduced FMD post-IR (placebo, ΔFMD: -4.4±0.7%; celecoxib, ΔFMD: -5.0±0.5%). One-day IPC completely prevented this effect (placebo, ΔFMD: -1.1±0.6%; celecoxib, ΔFMD: 0.0±0.7%; P<0.0001). Similarly, 7-day IPC demonstrated persistent endothelial protection post-IR (placebo, ΔFMD: -0.9±0.9%; celecoxib, ΔFMD: 0.0±0.8%; P<0.0001, P<0.0001 for ANOVA effect of IPC protocol). Celecoxib did not alter responses to IR in any protocol., Conclusions: Daily episodes of IPC provide sustained protection from IR-induced endothelial dysfunction in humans through a mechanism that appears cyclooxygenase-2-independent.

Remote preconditioning (rPeC) is a phenomenon by which short-time intermittent ischaemia-reperfusion (I/R) of a remote organ during ischaemia protects other organs from I/R injury (IRI). The aim of the present study was to investigate the protective effect of rPeC on renal IRI in rats. Rats were subjected to right nephrectomy and randomized as into a sham group (no additional intervention), an I/R group (subjected to 45 min left renal pedicle occlusion) and an rPeC group (subjected to four cycles of 5 min I/R of the left femoral artery administered at the beginning of renal ischaemia). After 24 h, blood, urine and tissue samples were collected. Compared with the sham group, I/R resulted in renal dysfunction, as evidenced by significantly lower creatinine clearance (CCr; 0.52 ± 0.06 vs 0.11 ± 0.02 mL/min, respectively) and higher fractional excretion of sodium (FE(Na) ; 0.80 ± 0.07% vs 2.46 ± 0.20%, respectively). This was accompanied by decreased superoxide dismutase (SOD; 6.9 ± 1.7 vs 26.7 ± 2.7 U/g tissue) and catalase (CAT; 20.2 ± 8.8 vs 32.2 ± 8.7 K/g tissue) activity in the I/R group, as well as decreased levels of reduced glutathione (GSH; 21.7 ± 8.1 vs 81.2 ± 20.2 μmol/g tissue) and increased malondialdehyde levels (MDA; 1.2 to 0.1 vs 0.5 ± 0.2 μmol/100 mg), cyclo-oxygenase (COX)-2 expression and histological damage. In the rPeC group, renal histology and function were significantly improved (CCr 0.32 ± 0.02 mL/min; FE(Na) 1.33 ± 0.12%) compared with the I/R group. Furthermore, compared with the I/R group, the rPeC group exhibited increases in SOD and CAT activity (22.8 ± 3.8 U/g tissue and 21.7 ± 8.6 K/g tissue, respectively), increased GSH levels (74.0 ± 4.9) and decreased MDA levels (1.1 ± 0.3 μmol/100 mg) and COX-2 expression. In conclusion, rPeC appears to exert protective effects against renal IRI. This protection may be a consequence of reductions in lipid peroxidation, intensification of anti-oxidant systems and downregulation of COX-2 expression. A simple approach, rPeC may be a promising strategy for protection against IRI in clinical practice., (© 2012 The Authors Clinical and Experimental Pharmacology and Physiology © 2012 Wiley Publishing Asia Pty Ltd.)

This investigation was designed to determine the participation of the vagus nerve and muscarinic receptors in the remote ischaemic preconditioning (rIPC) mechanism. New Zealand rabbits were anaesthetized, and the femoral artery was dissected. After 30 min of monitoring, the hearts were isolated and subjected to 30 min of global no-flow ischaemia and 180 min of reperfusion (non-rIPC group). The ventricular function was evaluated, considering the left ventricular developed pressure and the left ventricular end-diastolic pressure. In the rIPC group, the rabbits were subjected to three cycles of hindlimb ischaemia (5 min) and reperfusion (5 min), and the same protocol as that used in non-rIPC group was then repeated. In order to evaluate the afferent neural pathway during the rIPC protocol we used two groups, one in which the femoral and sciatic nerves were sectioned and the other in which the spinal cord was sectioned (T9-T10 level). To study the efferent neural pathway during the rIPC protocol, the vagus nerve was sectioned and, in another group, atropine was administered. The effect of vagal stimulation was also evaluated. An infarct size of 40.8 ± 3.1% was obtained in the non-rIPC group, whereas in rIPC group the infarct size decreased to 16.4 ± 3.5% (P < 0.05). During the preconditioning protocol, the vagus nerve section and the atropine administration each abolished the effect of rIPC on infarct size. Vagal stimulation mimicked the effect of rIPC, decreasing infarct size to 15.2 ± 4.7% (P < 0.05). Decreases in infarct size were accompanied by improved left ventricular function. We demonstrated the presence of a neural afferent pathway, because the spinal cord section completely abolished the effect of rIPC on infarct size. In conclusion, rIPC activates a neural afferent pathway, the cardioprotective signal reaches the heart through the vagus nerve (efferent pathway), and acetylcholine activates the ischaemic preconditioning phenomenon when acting on the muscarinic receptors.

Cerebral ischemia is a severe outcome that could cause cognitive and motor dysfunction, neurodegenerative diseases and even acute death. Although the existence of autophagy in cerebral ischemia is undisputable, the consensus has not yet been reached regarding the exact functions and influence of autophagy in cerebral ischemia. Whether the activation of autophagy is beneficial or harmful in cerebral ischemia injury largely depends on the balance between the burden of intracellular substrate targeted for autophagy and the capacity of the cellular autophagic machinery. Furthermore, the mechanisms underlying the autophagy in cerebral ischemia are far from clear yet. This brief review focuses on not only the current understanding of biological effects of autophagy, but also the therapeutic potentials of autophagy in ischemic stroke. There are disputes over the exact role of autophagy in cerebral ischemia. Application of chemical autophagy inhibitor (e.g., 3-methyladenine) or inducer (e.g., rapamycin) in vitro and in vivo was reported to protect or harm neuronal cell. Knockdown of autophagic protein, such as Beclin 1, was also reported to modulate the cerebral ischemia-induced injury. Moreover, autophagy inhibitor abolished the neuroprotection of ischemic preconditioning, implying a neuroprotective effect of autophagy. To clarify these issues on autophagy in cerebral ischemia, future investigations are warranted., (© 2012 Blackwell Publishing Ltd.)

Hypoxia is believed to be a crucial factor involved in cell adaptation to environmental stress. Islet transplantation, especially with immunoisolated islets, interrupts vascular connections, resulting in the substantially decreased delivery of oxygen and nutrients to islet cells. Insulin-producing pancreatic beta cells are known to be highly susceptible to oxygen deficiency. Such susceptibility to hypoxia is believed to be one of the main causes of beta-cell death in the post-transplantation period. Different strategies have been developed for the protection of beta cells against hypoxic injury and for oxygen delivery to transplanted islets. The enhancement of beta-cell defense properties against hypoxia has been achieved using various techniques such as gene transfection, drug supplementation, co-culturing with stem cells and cell selection. Technologies for oxygen delivery to transplanted islets include local neovascularization of subcutaneous sites, electrochemical and photosynthetic oxygen generation, oxygen refuelling of bio-artificial pancreas and whole body oxygenation by using hyperbaric therapy. Progress in the field of oxygen technologies for islet transplantation requires a multidisciplinary approach to explore and optimize the interaction between components of the biological system and different technological processes. This review article focuses mainly on the recently developed strategies for oxygenation and protection from hypoxic injury - to achieve stable and long-term normoglycaemia in diabetic patients with transplanted pancreatic islets., (Copyright © 2012 John Wiley & Sons, Ltd.)

Background: Remote ischemic preconditioning (RIPC) of the myocardium by limb ischemia/reperfusion may mitigate cardiac damage, but its interaction with the anesthetic regimen is unknown. We tested whether RIPC is associated with differential effects depending on background anesthesia. Specifically, we hypothesized that RIPC during isoflurane anesthesia attenuates myocardial injury in patients undergoing coronary artery bypass graft (CABG) surgery, and that effects may be different during propofol anesthesia., Methods: In a randomized, single-blinded, placebo-controlled prospective study, serum troponin I concentration (cTnI) (baseline, and 1, 6, 12, 24, 48, and 72 h postoperatively) were measured during isoflurane/sufentanil or propofol/sufentanil anesthesia with or without RIPC (three 5-min periods of intermittent left upper arm ischemia with 5 min reperfusion each) in non-diabetic patients (n = 72) with three-vessel coronary artery disease (ClinicalTrials.gov NCT01406678)., Results: RIPC during isoflurane anesthesia (n = 20) decreased the area under the cTnI time curve (cTnI AUC) (-50%, 190 ± 105 ng/ml × 72 h vs. 383 ± 262 ng/ml × 72 h, P = 0.004), and the peak (7.3 ± 3.6 ng/ml vs. 11.8 ± 5.5, P = 0.004) and serial (P < 0.041) postoperative cTnI when compared to isoflurane alone (n = 19). In contrast, RIPC during propofol anesthesia (n = 14) did not alter the cTnI AUC [263 ± 157 ng/ml × 72 h vs. 372 ± 376 ng/ml × 72 h (n = 19), P = 0.318] or peak postoperative cTnI (10.1 ± 4.5 ng/ml vs. 12 ± 8.2, P = 0.444). None of the patients experienced harm or side effects from the intermittent left arm ischemia., Conclusion: Thus, RIPC during isoflurane but not during propofol anesthesia decreased myocardial damage in patients undergoing CABG surgery. Accordingly, effects of RIPC evoked by upper limb ischemia/reperfusion depend on background anesthesia, with combined RIPC/isoflurane exerting greater beneficial effects under conditions studied., (© 2011 The Authors Acta Anaesthesiologica Scandinavica © 2011 The Acta Anaesthesiologica Scandinavica Foundation.)

1. Heme oxygenase 1 (HO-1) has been shown to play a pivotal role in the maintenance of cellular homeostasis when the liver undergoes sublethal stress, such as ischaemia-reperfusion (I/R) injury. In the present study, we investigated the protective role of HO-1 in hyperbaric oxygen (HBO) preconditioning against liver injury after I/R. 2. A total hepatic ischaemia (30 min) and reperfusion (60 min) injury model in rats was used in the present study. Preconditioned groups were exposed to HBO 24 h prior to the induction of I/R injury. Other groups were injected with zinc protoporphyrin IX (ZnPP) intraperitoneally 1 h before I/R to inhibit HO-1 activity. At the end of the reperfusion period, blood and liver samples were collected for the analysis of liver injury markers, morphological changes, and HO-1 expression and activity in the liver. 3. In untreated rats, I/R induced an increase in hepatic injury markers, such as plasma transaminases, inflammatory cytokines (tumour necrosis factor-α and interleukin-1β), and tissue malondialdehyde. However, HBO preconditioning attenuated the I/R-induced increases in these hepatic injury markers, and prevented both the necrosis and apoptosis of hepatocytes induced by I/R injury. Furthermore, HBO preconditioning significantly increased HO-1 mRNA and protein levels in the liver. In rats in which HO-1 activity had been inhibited with ZnPP pretreatment, the protective effects of HBO preconditioning against I/R injury were abolished. 4. In conclusion, HBO preconditioning can protect the liver against I/R injury and it appears that this effect might be mediated by the induction of HO-1., (© 2011 The Authors. Clinical and Experimental Pharmacology and Physiology © 2011 Blackwell Publishing Asia Pty Ltd.)

EtOH-PC reduces postischemic neuronal injury in response to cerebral (I/R). We examined the mechanism underlying this protective effect by determining (i) whether it was associated with a decrease in I/R-induced leukocyte-endothelial adhesive interactions in postcapillary venules, and (ii) whether the protective effects were mediated by activation of large conductance, calcium-activated potassium (BK(Ca)) channels. Mice were administered ethanol by gavage or treated with the BK(Ca) channel opener, NS1619, 24 hours prior to I/R with or without prior treatment with the BK(Ca) channel blocker, PX. Both CCA were occluded for 20 minutes followed by two and three hours of reperfusion, and rolling (LR) and adherent (LA) leukocytes were quantified in pial venules using intravital microscopy. The extent of DND, apoptosis and glial activation in hippocampus were assessed four days after I/R. Compared with sham, I/R elicited increases in LR and LA in pial venules and DND and apoptosis as well as glial activation in the hippocampus. These effects were attenuated by EtOH-PC or antecedent NS1619 administration, and this protection was reversed by prior treatment with PX. Our results support a role for BK(Ca) channel activation in the neuroprotective effects of EtOH-PC in cerebral I/R.

Hypoxic preconditioning stabilizes hypoxia-inducible factor (HIF) 1 alpha in the retina and protects photoreceptors against light-induced cell death. HIF-1 alpha is one of the major transcription factors responding to low oxygen tension and can differentially regulate a large number of target genes. To analyse whether photoreceptor-specific expression of HIF-1 alpha is essential to protect photoreceptors by hypoxic preconditioning, we knocked down expression of HIF-1 alpha specifically in photoreceptor cells, using the cyclization recombinase (Cre)-lox system. The Cre-mediated knockdown caused a 20-fold reduced expression of Hif-1 alpha in the photoreceptor cell layer. In the total retina, RNA expression was reduced by 65%, and hypoxic preconditioning led to only a small increase in HIF-1 alpha protein levels. Accordingly, HIF-1 target gene expression after hypoxia was significantly diminished. Retinas of Hif-1 alpha knockdown animals did not show any pathological alterations, and tolerated hypoxic exposure in a comparable way to wild-type retinas. Importantly, the strong neuroprotective effect of hypoxic preconditioning against light-induced photoreceptor degeneration persisted in knockdown mice, suggesting that hypoxia-mediated survival of light exposure does not depend on an autocrine action of HIF-1 alpha in photoreceptor cells. Hypoxia-mediated stabilization of HIF-2 alpha and phosphorylation of signal transducer and activator of transcription 3 (STAT 3) were not affected in the retinas of Hif-1 alpha knockdown mice. Thus, these factors are candidates for regulating the resistance of photoreceptors to light damage after hypoxic preconditioning, along with several potentially neuroprotective genes that were similarly induced in hypoxic knockdown and control mice.

Background: Isoflurane has been shown to induce tolerance against ischaemic injury in adult rodents. Although the delayed preconditioning effect of isoflurane has been demonstrated in neonatal rat pups, the acute preconditioning effects of isoflurane remained undetermined. The present study was therefore conducted to evaluate the acute preconditioning efficacy of isoflurane in neonatal rats subjected to a hypoxic-ischaemic (HI) injury., Methods: Post-natal day 7 pups were exposed to 1 or 2% isoflurane in oxygen for either 30, 60 or 90 min. Fifteen minutes after isoflurane exposure, the pups were subjected to an HI injury induced by left common carotid artery ligation and exposure to 8% oxygen for 2 h. Pups not exposed to isoflurane or not subjected to HI served as controls. Histopathologic injury to the cortex and hippocampus was evaluated 7 and 49 days after HI., Results: Isoflurane 2% exposure for 60 or 90 min before HI induced tolerance in the hippocampus and the number of normal neurons in the CA1 sector 7 days after HI was significantly greater than in non-preconditioned animals. This protective efficacy of isoflurane preconditioning was not observed 49 days after HI., Conclusions: Exposure of 2% isoflurane for at least 60 min is required to induce tolerance against HI injury in rat pups. However, this neuroprotective efficacy results in only transient neuroprotection.

Hypoxic and ischaemic brain damage are believed to involve excessive release of glutamate, and recent work shows that glutamate-induced damage in brain slices can be reduced by preconditioning with hypoxia or glutamate itself. Because adenosine is a powerful preconditioning agent, we have investigated whether adenosine could precondition against glutamate in vitro. In rat hippocampal slices, glutamate depolarization reduced the amplitudes of antidromic- and orthodromic-evoked potentials, with only partial recovery. Applying adenosine before these insults failed to increase that recovery. Ouabain also produced depolarization with partial reversibility, but adenosine pretreatment increased the extent of recovery. The preconditioning effect of adenosine on ouabain responses was prevented by blocking receptors for N-methyl-D-aspartate (NMDA), but not receptors for kainate or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and was blocked by inhibiting nitric oxide synthase. Preconditioning was also abolished by the ATP-dependent potassium channel blockers, glibenclamide (cytoplasmic) or 5-hydroxydecanoate (mitochondrial). We conclude that adenosine does not precondition against glutamate in hippocampal slices, but that it does precondition against ouabain with a pharmacology similar to studies in vivo. Ischaemic neuronal damage is a complex of many factors, and because adenosine can precondition against ischaemic neuronal damage, its failure to protect against glutamate highlights limitations of using glutamate alone as a model for ischaemia. Because damage following ischaemia, trauma or excitotoxicity also involves reduced Na(+),K(+)-ATPase activity, and adenosine can precondition against ouabain, we propose that ouabain-induced damage represents an additional or alternative model for the contribution to cell damage of Na(+),K(+)-ATPase loss, this being more relevant to the mechanisms of preconditioning.

Ischaemic preconditioning (IPC) protects the heart and kidneys against ischaemia-reperfusion (I/R) injury. It has been shown that opioid receptor activation can mimic cardiac IPC. In a kidney model of I/R, a single dose of morphine failed to mimic IPC. The aim of the present study was to determine the role of chronic morphine (dependence) in protection against renal I/R injury. Male Wistar rats were treated with increasing doses of morphine (20-30 mg/kg per day, s.c., for 5 days) to develop morphine dependence (MD). Three weeks before the I/R procedure, the right kidney was removed. Ischaemia-reperfusion injury was induced by clamping the left renal artery for 45 min, followed by 24 h reperfusion. Some MD rats were pretreated with naloxone (5 mg/kg, s.c.). Twenty-four hours later, creatinine and sodium concentrations were measured in serum and urine, then creatinine clearance (CCr) and the fractional excretion of sodium (FE(Na)) were calculated. Blood urea nitrogen (BUN) was measured only in serum samples. Kidneys were also assessed histologically for evidence of tissue injury. In the present study, MD decreased tissue injury (histological score), serum creatinine and BUN levels, increased CCr and decreased FE(Na) after I/R. Pretreatment with naloxone attenuated the protective effects of MD. Morphine dependence did not have any significant effect on urine volume. In conclusion, it seems that morphine dependence protects the kidney against I/R injury via opioid receptor-dependent pathways. Further studies are required to clearly determine the mechanisms involved.

Background and Aim: Postoperative neurologic deficit is the most devastating complication after surgical thoracic aorta repair. Cerebrospinal fluid drainage and some medications are used for spinal cord protection during and after the operation., Methods: A 25-year-old patient applied to our clinic with a traumatic descending aortic aneurysm. We performed a surgical repair for the aneurysm but could not achieve to place a lumbar catheter to provide cerebrospinal fluid drainage. Levosimendan was chosen for spinal cord ischemic preconditioning because of its vasodilatory effects., Results: Postoperative course was uneventful. Hemodynamic and neurologic complication was not observed, and the patient was discharged from the hospital in the postoperative 5th day., Conclusions: Levosimendan can be used for preconditioning and spinal cord protection from ischemic injury during descending aorta repair. We clearly benefit from the vasodilator peculiarity of the drug for improving spinal cord perfusion.

Background: Diazoxide, pharmacological openers of mitochondrial ATP-sensitive potassium channels have been shown to induce early pre-conditioning in the spinal cord. Here, the authors investigated whether diazoxide also induce delayed pre-conditioning and thereby reduce neurologic complications using a rabbit model of spinal cord ischemia., Methods: Infrarenal blood flow was interrupted for 20 min in 21 rabbits. Non-treated control animals received no pre-treatment. Diazoxide (5 mg/kg) were given 48 h before 20 min ischemia in the 48-h DZ group, whereas 15-min DZ group received diazoxide (5 mg/kg) 15 min before 20-min ischemia. Neurological functions were evaluated using Johnson scores for 3 days after reperfusion, after which, spinal cords were procured for hematoxylin and eosin staining for cell counting., Results: Johnson scores revealed a marked improvement in both the diazoxide-treated groups vs. the non-treated control group at 3, 24, 48, and 72 h after reperfusion (P<0.01). The histologic changes were proportional to the Johnson scores, with better preservation of motor neuron numbers in the animals of the 48-h DZ and 15-min DZ group relative to the non-treated controls (81+/-12, 90+/-10, 50+/-23 motor neurons, respectively, P<0.01). No difference was found between the 48-h DZ group and 15-min DZ group with respect to the Johnson scores or neuron numbers., Conclusions: The study demonstrates that pre-treatment with diazoxide 48 h before ischemia, induce delayed pharmacological pre-conditioning, thereby significantly improving clinical neurologic scores and histologic findings in this animal model.

Background: Living donor hepatectomies in liver transplantation are usually performed without inflow occlusion. We hypothesized that selective ischaemia/reperfusion (SIR) before partial hepatectomy (PH) without inflow occlusion might exert a hepatoprotective effect., Methods: In the SIR groups, rats were subjected to a selective 30-min ischaemia to the liver that remained after PH, followed by various durations of reperfusion before 70% PH without inflow occlusion. The control group underwent 70% PH alone., Results: As assessed by serum aspartate and alanine aminotransferase levels, 30-min reperfusion was highly protective against liver injury compared with 10-min reperfusion, showing the same levels as that of the control group. After PH in the 10-min reperfusion group, apoptotic cells were significantly higher and the 7-day survival rate was significantly lower than that of the 30-min reperfusion group and the control group. In the 30-min reperfusion group, the expression of heat shock protein 70 (HSP70) was significantly higher than that in the 10-min reperfusion group, while apoptosis was improved to the levels of the control group. In the SIR groups, liver regeneration was significantly enhanced, with markedly increased levels of interleukin 6 (IL-6) compared with the control group., Conclusions: The timing of SIR before PH without inflow occlusion seemed to be the most important factor for determining liver damage and survival in the context of HSP70 production, while high levels of IL-6 appear to be associated with liver regeneration after PH. The procedure of SIR before PH is not recommended because the SIR groups did not overcome the control group.

Aim: Intermittent limb ischaemia prior to cardiac ischaemia is a cardioprotective stimulus. This study was to investigate whether this peripheral stimulus had any effects on basal coronary blood flow and resistance, and to explore its potential mechanisms by studying the effect of femoral nerve transection and Katp blockade by glibenclamide., Methods: Remote ischaemic preconditioning (rIPC) was induced by four 5-min cycles of lower limb ischaemia. Coronary resistance was measured using standard formulae and coronary blood flow in the left anterior descending artery (LAD) by a flow probe. In experiment 1, coronary ischaemia was induced by inflation of a cuff placed around the mid-LAD, and inflated until cessation of flow. Left ventricular (LV) function was assessed using dp/dt and Tau at 1 and 30 min of ischaemia. Experiment 1: 20 pigs were randomized to control (n = 6), rIPC (n = 7) or femoral nerve transection + rIPC (n = 7) groups. The femoral nerve was transected before the rIPC protocol. All data were collected at fixed heart rates of 120 bpm. Coronary resistance was decreased and flow was increased significantly by the rIPC stimulus (P = 0.003, P = 0.016, paired t-test), and these changes were preserved after femoral nerve transection. Experiment 2: 19 pigs were randomized to control (n = 5), rIPC (n = 8) or glibenclamide-treated rIPC (n = 6) groups. Data were collected at baseline, and during incremental pacing between 120 and 180 bpm., Results: Experiment 1: Coronary resistance was decreased and flow was increased significantly by rIPC stimulus (P = 0.003, P = 0.016, paired t-test), and these changes were preserved after femoral nerve transaction. rIPC was associated with superior LV function (dp/dt(max)) at 30 min, compared with controls and the rIPC + femoral nerve transaction group. Experiment 2: Coronary resistance was significantly lower, and LAD flow was significantly higher in rIPC group (P < 0.0001, P = 0.0008, two-way anova). These effects were reversed in the glibenclamide group., Conclusion: The rIPC stimulus leads to reduced coronary resistance and increased flow. This effect, while modified by glibenclamide appears to be a generic effect of remote ischaemia rather than a direct preconditioning effect.