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Background: In pediatric critical care, vasoactive/inotropic support is widely used in patients with heart failure, but it remains controversial because the influence of multiple medications and the interplay between their inotropic and vasoactive effects on a given patient are hard to predict. Robust evidence supporting their use and quantifying their effects in this group of patients is scarce., Study Question: The aim of this study was to characterize the effect of vasoactive medications on various cardiovascular parameters in pediatric patient with decreased ejection fraction., Study Design: Clinical-data based physiologic simulator study., Measure and Outcomes: We used a physics-based computer simulator for quantifying the response of cardiovascular parameters to the administration of various types of vasoactive/inotropic medications in pediatric patients with decreased ejection fraction. The simulator allowed us to study the impact of increasing medication dosage and the simultaneous administration of some vasoactive agents. Correlation and linear regression analyses yielded the quantified effects on the vasoactive/inotropic support., Results: Cardiac output and systemic venous saturation significantly increased with the administration of dobutamine and milrinone in isolation, and combination of milrinone with dobutamine, dopamine, or epinephrine. Both parameters decreased with the administration of epinephrine and norepinephrine in isolation. No significant change in these hemodynamic parameters was observed with the administration of dopamine in isolation., Conclusions: Milrinone and dobutamine were the only vasoactive medications that, when used in isolation, improved systemic oxygen delivery. Milrinone in combination with dobutamine, dopamine, or epinephrine also increased systemic oxygen delivery. The induced increment on afterload can negatively affect systemic oxygen delivery., Competing Interests: The authors have no conflicts of interest to declare., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Nonintravenous inotropic-delivery options are needed for patients with inotropic-dependent heart failure (HF) to reduce the costs, infections and thrombotic risks associated with chronic central venous catheters and home infusion services., Methods: We developed a novel, concentrated formulation of nebulized milrinone for inhalation and evaluated the feasibility, safety and pharmacokinetic profile in a prospective, single-arm, phase I clinical trial. We enrolled 10 patients with stage D HF requiring inotropic therapy during a hospital admission for acute HF. Milrinone 60 mg/4 mL was inhaled via nebulization 3 times daily for 48 hours. The coprimary outcomes were adverse events and pharmacokinetic profiles of inhaled milrinone. Acute changes in hemodynamic parameters were secondary outcomes., Results: A concentrated nebulized milrinone formulation was well tolerated, without hypotensive events, arrhythmias or inhalation-related adverse events requiring discontinuation. Nebulized milrinone produced serum concentrations in the goal therapeutic range with a median plasma milrinone trough concentration of 39 (17-66) ng/mL and a median peak concentration of 207 (134-293) ng/mL. There were no serious adverse events. From baseline to 24 hours, mean pulmonary artery saturation increased (60% ± 7%-65 ± 5%; P = 0.001), and mean cardiac index increased (2.0 ± 0.5 mL/min/1.73m 2 -2.5 ± 0.1 mL/min/1.73m 2 ; P = 0.001) with nebulized milrinone., Conclusions: In a proof-of-concept study, a concentrated, nebulized milrinone formulation for inhalation was safe and produced therapeutic serum milrinone concentrations. Nebulized milrinone was associated with improved hemodynamic parameters of cardiac output in a population with advanced HF. These promising results require further investigation in a longer-term trial in patients with inotrope-dependent advanced HF., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Accidental hypothermia, recognized by core temperature below 35 °C, is a lethal condition with a mortality rate up to 25%. Hypothermia-induced cardiac dysfunction causing increased total peripheral resistance and reduced cardiac output contributes to the high mortality rate in this patient group. Recent studies, in vivo and in vitro, have suggested levosimendan, milrinone and isoprenaline as inotropic treatment strategies in this patient group. However, these drugs may pose increased risk of ventricular arrhythmias during hypothermia. Our aim was therefore to describe the effects of levosimendan, milrinone and isoprenaline on the action potential in human cardiomyocytes during hypothermia., Methods: Using an experimental in vitro-design, levosimendan, milrinone and isoprenaline were incubated with iCell 2 hiPSC-derived cardiomyocytes and cellular action potential waveforms and contraction were recorded from monolayers of cultured cells. Experiments were conducted at temperatures from 37 °C down to 26 °C. One-way repeated measures ANOVA was performed to evaluate differences from baseline recordings and one-way ANOVA was performed to evaluate differences between drugs, untreated control and between drug concentrations at the specific temperatures., Results: Milrinone and isoprenaline both significantly increases action potential triangulation during hypothermia, and thereby the risk of ventricular arrhythmias. Levosimendan, however, does not increase triangulation and the contractile properties also remain preserved during hypothermia down to 26 °C., Conclusions: Levosimendan remains a promising candidate drug for inotropic treatment of hypothermic patients as it possesses ability to treat hypothermia-induced cardiac dysfunction and no increased risk of ventricular arrhythmias is detected. Milrinone and isoprenaline, on the other hand, appears more dangerous in the hypothermic setting., (© 2023. Norwegian Air Ambulance Foundation.)

Background: Maintaining a low left atrial pressure (LAP) in off-pump coronary artery bypass grafting (OPCAB) is desirable. This study was done to compare the effects of intravenous levosimendan or milrinone on LAP at different stages of OPCAB., Materials and Methods: After institutional ethics committee clearance, this two-arm double-blind randomized control trial was done in 44 adult patients with triple vessel coronary artery disease undergoing OPCAB at cardiac OT of IPGME&R, Kolkata. The patients were randomly allocated into two groups receiving intraoperative either levosimendan or milrinone. Pulmonary capillary wedge pressure (PCWP) was compared as the primary outcome parameter, whereas other echocardiographic and hemodynamic parameters were also assessed during six stages of OPCAB, that is, after sternotomy, proximal(s), left anterior descending artery (LAD), obtuse marginal (OM), posterior descending artery (PDA) grafting, and before sternal closure. Numerical parameters were compared using Student's unpaired two-tailed t-test., Results: PCWP was found to be significantly lower (P < 0.05) in the levosimendan group during proximal (P = 0.047), LAD (P = 0.018), OM (P < 0.0001), PDA grafting (P = 0.028), and before sternal closure (P = 0.015). Other parameters indicate LAP, that is, from mitral early diastolic inflow velocity to mitral annular early diastolic velocity ratio (E/e'), which indicated significantly lower LAP in levosimendan group during LAD, OM, and PDA grafting and before sternal closure. Conclusion: Levosimendan may be used as a primary inotrope in terms of better reduction in left atrial pressure during different stages of OPCAB, translating to a decrease in left ventricular end-diastolic pressure, therefore maintaining optimum coronary perfusion pressure, which is the primary goal of the surgery.

Aim: To investigate the efficacy of zinc oxide nanoparticles (ZnO-NPs) and/or milrinone (MIL) on renal ischemia/reperfusion injury (I/RI) in rats and their possible underlying mechanisms., Materials and Methods: Forty-eight adult male Sprague-Dawley albino rats were randomly assigned into six equal-sized groups (n = 8): normal control, sham-operated, I/R group (45 min/24 h), ZnO-NPs group (10 mg/kg i.p.), MIL group (0.5 mg/kg i.p.), and ZnO-NPs + MIL group in the same previous doses., Key Findings: In comparison to the I/R-operated group, administration of either ZnO-NPs or MIL significantly decreased serum creatinine and urea concentrations, and renal vascular permeability (p < 0.05). The oxidative stress was significantly declined, as evidenced by increased GPx, CAT, and SOD activities and decreased MDA and NO concentrations. Renal expressions of TNF-α, NF-κB, KIM-1, NGAL, and caspase-3 decreased significantly, while Nrf2 increased significantly. Histopathology investigation revealed improvement with minimal renal lesions and fibrosis after ZnO-NPs or MIL treatments. The combined treatments synergistically improved the studied parameters more than either treatment alone. These findings were validated by molecular modeling, which revealed that MIL inhibited TNF-α, NF-kB, caspase-3, KIM-1 and NGAL., Significance: Both ZnO-NPs and MIL exerted cytoprotective effects against acute renal I/RI, and a combination of both was found to be even more effective. This renoprotective effect is suggested to be mediated through activation of Nrf2 and the prevention of the NF-κB activation-induced oxidative stress and inflammation, which may strengthen the potential role of ZnO-NPs or MIL in renal I/RI protection during surgical procedures., Competing Interests: Declaration of competing interest The authors have no competing interests to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Traumatic brain injury is still an important health problem worldwide. Traumatic brain injury not only causes direct mechanical damage to the brain but also induces biochemical changes that lead to secondary nerve cell loss. In this study, we investigated the neuroprotective effect of milrinone after traumatic brain injury (TBI) in a rat model., Methods: Forty male Wistar albino rats, were used. Rats were divided into 4 groups: 1) sham, 2) TBI, 3) TBI + Ringers, and 4) TBI + Milrinone. In group 1 (sham), only craniotomy was performed. In group 2 (TBI), TBI was performed after craniotomy. In group 3 (TBI + Ringer), TBI was performed after craniotomy and intraperitoneal Ringers solution was given immediately afterward. Group 4 (TBI + Milrinone), TBI was performed after craniotomy, and milrinone was given 1.0 mg/kg milrinone intraperitoneally directly (0.5 mg/kg milrinone intraperitoneally again 24 hours, 48 hours, and 72 hours after trauma). Tests were performed for neurological and neurobehavioral functions. Immunohistochemistry and histopathology studies were performed., Results: In group 4 compared with group 2 and group 3 groups, tests for neurological functions and neurobehavioral functions were significantly better. In the milrinone treatment used in group 4, plasma and brain tissue tumor necrosis factor, 8-OH 2-deoxyguanosine , and interleukin 6 levels were significantly decreased, and increased plasma and tissue IL-10 levels were detected. Histopathological spinal cord injury and apoptotic index increased in groups 2 and 3, while significantly decreasing in group 4., Conclusions: This study shows for the first time that the anti-inflammatory, antioxidant and antiapoptotic properties of milrinone may be neuroprotective after TBI., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: The role of intravenous (IV) inotropes in the treatment of ambulatory patients with advanced heart failure (HF) remains controversial., Methods: This was a retrospective study of patients with advanced HF. Patients on home IV milrinone, who remained on it for at least 3 months, were included. We compared the data from 3 months before starting IV milrinone to 3 months after initiating therapy. A subset of patients who remained on milrinone for 6 months or longer was analysed separately., Results: A total of 90 patients remained on continuous IV milrinone for 3 months, and 55 patients were treated for 6 months or longer. In both groups, improvements in cardiac index (1.86-2.25, p<0.001 and 1.9-2.38, p<0.0001), New York Heart Association (NYHA) class (3.32-2.76, p<0.0001 and 3.25-2.72, p=0.001), and liver function were noted. In the 6-month group, there was also a decrease in mean hospitalised days per patient (9.40 vs 4.12, p<0.001) and an improved tolerance of beta blocker therapy (83.3% vs 98.1%, p=0.006)., Conclusion: Long-term IV use of milrinone is associated with improvement in haemodynamics, functional class, tolerance of medical therapy, and decrease in hospitalised days., (Copyright © 2022. Published by Elsevier B.V.)

Background: Catecholamine-storm is considered the major cause of enterovirus 71-associated cardiopulmonary death. To elucidate the effect of milrinone on cardiac mitochondria and death, a rat model of catecholamine-induced heart failure was investigated., Methods: Young male Spray-Dawley rats received a continuous intravenous infusion of norepinephrine then followed by co-treatment with and without milrinone or esmolol. Vital signs were monitored and echocardiography was performed at indicated time points. At the end of experiments, hearts were extracted to study mitochondrial function, biogenesis, and DNA copy numbers., Results: Hypernorepinephrinemia induced persistent tachycardia, hypertension, and high mortality and significantly impaired the activities of the electron transport chain and suppressed mitochondrial DNA copy number, mitochondrial transcription factor A and peroxisome proliferator-activated receptor-gamma coactivator 1-α. Norepinephrine-induced hypertension could be significantly suppressed by milrinone and esmolol. Milrinone improved but esmolol deteriorated the survival rate. The left ventricle was significantly enlarged shortly after norepinephrine infusion but later gradually reduced in size by milrinone. The impairment and suppression of mitochondrial function could be significantly reversed by milrinone but not by esmolol., Conclusions: Milrinone may protect the heart via maintaining mitochondrial function from hypernorepinephrinemia. This study warrants the importance of milrinone and the preservation of mitochondrial function in the treatment of catecholamine-induced death., Impact: Milrinone may protect the heart from hypernorepinephrinemia-induced death via maintaining myocardial mitochondrial activity, function, and copy number. Maintenance of cardiac mitochondrial function may be a potential therapeutic strategy in such catecholamine-induced heart failure., (© 2022. The Author(s), under exclusive licence to the International Pediatric Research Foundation, Inc.)

Buffalo has many excellent economic traits and it is one of the greatest potential livestock. Compared with cattle, buffalo has poorer reproductivity, it is of great significance to improve the development potential of oocytes. Buffalo oocyte in vitro maturation (IVM) has been widely used in production, but the poor development ability of bovine oocytes IVM limits the development of buffalo reproductivity. Milrinone as a phosphodiesterase inhibitor could affect the maturation of oocytes in goat and mice, but there have been few reported studies in water buffalo. To optimize buffalo oocyte in vitro maturation systems, the effects of phosphodiesterase inhibitor (milrinone) on pre-maturation culture of buffalo oocytes were investigated in this study. Buffalo cumulus-oocyte complexes (COCs) were cultured in medium with different concentrations (0, 12, 25, 50 and 100 mol/l) of milrinone for different times (0, 4, 8, 12, 16, 22 and 24 h). The results showed that the buffalo COCs nuclear maturation process could be inhibited by milrinone (25-100 mol/l) in a dose-dependent manner. The inhibitory effect of milrinone on in vitro maturation of buffalo oocytes did not decrease with the extension of time. This indicated that milrinone can be used as a nuclear maturation inhibitor during the maturation process in buffalo oocytes. In addition, milrinone can inhibit the effect of follicle stimulating hormone (FSH)-induced IVM of buffalo oocytes, but with time FSH partially eliminated the inhibition. Therefore, inhibition of milrinone on the nuclear maturation of buffalo oocytes was reversible, and buffalo oocytes can mature normally after the inhibition is lessened.

Abstract: OR-1855 and OR-1896 are 2 hemodynamically active metabolites of the inodilator levosimendan, with calcium sensitizing activity, but their mechanism of action is still not fully understood. It has been previously reported that the positive inotropic effect of levosimendan is not potentiated by the adenylate cyclase activator forskolin, whereas forskolin does potentiate the effects of the phosphodiesterase (PDE) inhibitor milrinone. To ascertain whether the active metabolites follow the same pattern of levosimendan, the positive inotropic effects of OR- 1855 and OR-1896 were studied in guinea-pig-isolated papillary muscle in the presence and absence of forskolin. OR-1855 and OR-1896 were also tested as inhibitors of PDE-III and PDE-IV. Our results show that 0.1 µM forskolin did not potentiate the positive inotropic effect of OR-1855 or OR-1896, as in the case of the parent compound levosimendan. As in previous studies, the positive inotropic effect of milrinone was markedly potentiated in the presence of forskolin. From these data, we propose an explanation for the divergent behavior of the calcium sensitizing drugs and PDE inhibitors., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Tetralogy of Fallot is one of the most frequent cyanotic heart diseases in our country, occupying the second place reported by the national health program 2007- 2012 and its prevalence is around 11%. Patients undergoing correction for tetralogy of Fallot are considered patients with a prolonged ischemic time and a high risk of presenting low cardiac output syndrome., Objective: To compare levosimendan with milrinone to prevent low cardiac output syndrome in patients undergoing tetralogy of Fallot correction., Material and Methods: Randomized controlled open, prospective, longitudinal and comparative clinical trial. The sample size consisted of 19 patients, with a 95% confidence level. Group 1: levosimendan 0.1 mcg/kg/min from anesthetic induction. Group 2: conventional management with milrinone 0.5 mcg/kg/min., Results: When comparing the final measurements, it can be observed that the mean arterial pressure of the intervention group (levosimendan) was statistically significant (p = 0.04), both in the intraoperative measurement and in the final measurement. When comparing uresis, we found that the intervention group had a greater amount of uresis (p = 0.03). Regarding lactate, both in the intraoperative measurement (p = 0.002) and in the final measurement (p = 0.02), a lower amount was found in the intervention group., Conclusions: The results in favor of the use of levosimendan were reported, demonstrating the prevention of low cardiac output syndrome., (© 2022 Revista Medica del Instituto Mexicano del Seguro Social.)

Aims: Routine, intermittent inotropic therapy (IIT) is still applied in advanced heart failure (HF) patients either as a bridge to definitive treatment or as a mean to improve quality of life (QOL), despite limited evidence to support its' use. Given recent reports of improved QOL and reduced HF hospitalization, with levosimendan compared with placebo in advanced HF patients, we aimed to assess the effects of switching a small group of milrinone-treated patients to levosimendan. This was performed as part of a protocol for changing our ambulatory HF clinic milrinone-based IIT to levosimendan., Methods and Results: Single-centre study of consecutive ambulatory advanced HF patients that received ≥4 cycles of once-weekly milrinone IIT at our HF outpatient clinic, who were switched to levosimendan IIT. All patients had left ventricular ejection fraction ≤35%, elevated B-natriuretic peptide (BNP), and were in New York Heart Association Classes III-IV despite maximally tolerated guideline directed medical therapy. Patients were evaluated using BNP levels, echocardiography, cardio-pulmonary exercise test, and HF QOL questionnaire before and after 4 weeks of levosimendan IIT. The cohort included 11 patients, 10 (91%) were male and the mean age was 76 ± 12 years. After 4 weeks of levosimendan therapy, maximal O 2 consumption improved in 8/9 (89%) by a mean of 2.28 mL/kg [95% CI -0.22-3.38, P = 0.05]. BNP levels decreased in 9/11 (82%) levosimendan treated patients, from a median of 1015 ng/L [261-1035] to 719 ng/L [294-739], (P < 0.01). QOL as measure by the EQ-5D-5L questionnaire improved in 8/11 (82%) patients after levosimendan IIT, by a median of two points [95% CO -4.14-0.37, P = 0.09]. On echocardiography, peak systolic annular velocity (S') increased after levosimendan IIT by an average of 3 cm/s [95% CI 0.16-2.10, P = 0.03]., Conclusions: In this small-scale study of ambulatory advanced HF patients, we observed improvements in right ventricular systolic function, maximal O 2 consumption, and BNP after switching from milrinone to levosimendan based IIT., (© 2022 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Background: A sepsis model was created, induced by cecal ligation and puncture (CLP), in juvenile rat groups. Milrinone (MIL), which is known to have a modulatory effect on pro-inflammatory cytokines, was administered to the designated rat groups in the early period before severe sepsis developed. The study was aimed at investigating the possible protective effects of milrinone on the lung and kidney tissues of rats in the late phase of sepsis., Methods: The rat pups were divided into seven groups with six animals in each group: (1) healthy rats who received no drug; (2) CLP-S12 (sacrificed at hour 12); (3) CLP-S24 (sacrificed at hour 24); (4) CLP-MIL1-S12 (administered with 0.5 mg/kg milrinone at hour 1 and sacrificed at hour 12); (5) CLP-MIL1-S24 (administered with 0.5 mg/kg milrinone at hour 1 and sacrificed at hour 24): (6) CLP-MIL12-S24 (administered with 0.5 mg/kg milrinone at hour 12 and sacrificed at hour 24), (7) and CLP-MIL1,12-S24 (administered with 0.5 mg/kg milrinone at hours 1 and 12 and sacrificed at hour 24)., Results: Significant differences were found between the early and late administration of milrinone in terms of both molecular and histopathological results. The results showed that the tissues were significantly preserved in the groups in which milrinone had been started in the early period compared to the sepsis control groups and the groups in which milrinone had been started in the late period., Conclusions: In addition to the positive inotropic effects of milrinone, its immunomodulatory properties that result in decreased cytokine storm can be beneficial during early period of sepsis., (© 2022 Japan Pediatric Society.)

Congestive heart failure, a prominent cardiovascular disease results primarily from myocardial infarction or ischemia. Milrinone (MRN), a widely used clinical drug for heart failure, improves myocardial contractility and cardiac function through its inotropic and vasodilatory effects. However, lacking target specificity, it exhibits low bioavailability and lower body retention time. Therefore, in this study, angiotensin II (AT1) peptide conjugated human serum albumin nanoparticles (AT1-HSA-MRN-NPs) have been synthesized for targeted delivery of MRN to the myocardium, overexpressing AT1 receptors under heart failure. The NPs were surface functionalized through a covalent conjugation reaction between HSA and AT1. Nanoparticle size was 215.2±4.7 nm and zeta potential -28.8±2.7 mV and cumulative release of MRN was ~72% over 24 hrs. The intracellular uptake of nanoparticles and cell viability was studied in H9c2 cells treated with AT1-MRN-HSA-NPs vs the control non-targeted drug, MRN Lactate under normal, hypoxic and hypertrophic conditions. The uptake of AT1-HSA-MRN-NPs in H9c2 cells was significantly higher as compared to non-targeted nanoparticles, and the viability of H9c2 cells treated with AT1-MRN-HSA-NPs vs MRN Lactate was 73.4±1.4% vs 44.9±1.4%, respectively. Therefore, AT1-HSA-MRN-NPs are safe for in vivo use and exhibit superior targeting and drug delivery characteristics for treatment of heart failure., Competing Interests: The authors declare no competing interests.

Background: Cardiogenic shock (CS) is associated with significant morbidity and mortality. The impact of beta-blocker (BB) use on patients who develop CS remains unknown. We sought to evaluate the clinical outcomes and hemodynamic response profiles in patients treated with BB in the 24 h prior to the development of CS., Methods: Patients with CS enrolled in the DObutamine compaREd to MIlrinone trial were analyzed. The primary outcome was a composite of all-cause mortality, resuscitated cardiac arrest, need for cardiac transplant or mechanical circulatory support, non-fatal myocardial infarction, transient ischemic attack or stroke, or initiation of renal replacement therapy. Secondary outcomes included the individual components of the primary composite and hemodynamic response profiles derived from pulmonary artery catheters., Results: Among 192 participants, 93 patients (48%) had received BB therapy. The primary outcome occurred in 47 patients (51%) in the BB group and in 52 (53%) in the no BB group (RR 0.96; 95% CI 0.73-1.27; P = 0.78) throughout the in-hospital period. There were fewer early deaths in the BB group (RR 0.41; 95% CI 0.18-0.95; P = 0.03). There were no differences in other individual components of the primary outcome or in hemodynamic response between the two groups throughout the remainder of the hospitalization., Conclusions: BB therapy in the 24 h preceding the development of CS did not negatively influence clinical outcomes or hemodynamic parameters. On the contrary, BB use was associated with fewer deaths in the early resuscitation period, suggesting a paradoxically protective effect in patients with CS. Trial registration ClinicalTrials.gov Identifier: NCT03207165., (© 2021. The Author(s).)

Background: Splanchnic vasodilation by inodilators is an argument for their use in critical cardiac dysfunction. To isolate peripheral vasoactivity from inotropy, such drugs were investigated, and contrasted to vasopressors, in a fixed low cardiac output (CO) model resembling acute cardiac dysfunction effects on the gastrointestinal tract. We hypothesized that inodilators would vasodilate and preserve the aerobic metabolism in the splanchnic circulation in low CO., Methods: In anesthetized pigs, CO was lowered to 60% of baseline by partial inferior caval vein balloon inflation. The animals were randomized to placebo (n = 8), levosimendan (24 μg kg-1 bolus, 0.2 μg kg-1 min-1, n = 7), milrinone (50 μg kg-1 bolus, 0.5 μg kg-1 min-1, n = 7), vasopressin (0.001, 0.002 and 0.006 U kg-1 min-1, 1 h each, n = 7) or norepinephrine (0.04, 0.12, and 0.36 μg kg-1 min-1, 1 h each, n = 7). Hemodynamic variables including mesenteric blood flow were collected. Systemic, mixed-venous, mesenteric-venous, and intraperitoneal metabolites were analyzed., Results: Cardiac output was stable at 60% in all groups, which resulted in systemic hypotension, low superior mesenteric artery blood flow, lactic acidosis, and increased intraperitoneal concentrations of lactate. Levosimendan and milrinone did not change any circulatory variables, but levosimendan increased blood lactate concentrations. Vasopressin and norepinephrine increased systemic and mesenteric vascular resistances at the highest dose. Vasopressin increased mesenteric resistance more than systemic, and the intraperitoneal lactate concentration and lactate/pyruvate ratio., Conclusion: Splanchnic vasodilation by levosimendan and milrinone may be negligible in low CO, thus rejecting the hypothesis. High-dose vasopressors may have side effects in the splanchnic circulation., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by the Shock Society.)

Pulmonary hypertension (PH), an often unrelenting disease that carries with it significant morbidity and mortality, affects not only the pulmonary vasculature but, in turn, the right ventricle as well. The survival of patients with PH is closely related to the right ventricular function. Therefore, having an understanding of how to manage right ventricular failure (RVF) and acute pulmonary hypertensive crises is imperative for clinicians who encounter these patients. This review addresses the management of these patients in detail, addressing: (a) the pathophysiology of RVF, (b) intensive care monitoring of these patients in the intensive care unit, (c) imaging of the right ventricle, (d) intubation and mechanical ventilation, (e) inotrope and vasopressor selection, (f) pulmonary vasodilator use, (g) interventional and surgical procedures for the acutely failing right ventricle, and (h) mechanical support for RVF., (© 2020 Wiley Periodicals, Inc.)

Ischemic preconditioning and postconditioning are strong measures preserving the heart against ischemia-reperfusion injury in experimental setting but are too invasive and impractical for clinical routine. The cardioprotective effects of ischemic preconditioning and postconditioning can be imitated pharmacologically, for example, with the phosphodiesterase inhibitors sildenafil and milrinone. We hypothesize that sildenafil-induced preconditioning is concentration dependent and further that a combined treatment of "nonprotective" versus "protective" concentrations of sildenafil and milrinone leads to a significant infarct size reduction. Experiments were performed on isolated hearts of male Wistar rats, randomized into 12 groups, mounted onto a Langendorff system, and perfused with Krebs-Henseleit buffer. All hearts underwent 33 minutes ischemia and 60 minutes of reperfusion. For determination of a concentration-dependent effect of sildenafil, hearts were perfused with increasing concentrations of sildenafil (0.1-1 µM) over 10 minutes before ischemia. In a second series of experiments, hearts were treated with 0.3 µM sildenafil or 1 µM milrinone as the "protective" concentrations. A higher concentration of respective drugs did not further reduce infarct size. In addition, a combination of "protective" and "nonprotective" concentrations of sildenafil and milrinone was applied. Sildenafil and milrinone in lower concentrations led to significant infarct size reduction, whereas combining both substances in cardioprotective concentrations did not enhance this effect. Sildenafil in a concentration of 0.3 µM induces myocardial protection. Furthermore, treatment with sildenafil and milrinone in lower concentrations had an equally strong cardioprotective effect regarding infarct size reduction compared with the administration of "protective" concentrations.

Background: The management of severe persistent pulmonary hypertension (PPHN) can be very challenging in many resource-limited centers without access to inhaled nitric oxide or extracorporeal membrane oxygenation., Objectives: The current study aimed to investigate the efficacy of oral sildenafil and intravenous milrinone infusion and compare the effects of these drugs in combination versus as monotherapy in neonates with PPHN., Methods: A double-blind randomized controlled trial was conducted in which neonates with PPHN were divided into three groups of 20 patients each: group 1 received oral sildenafil starting at 0.5 mg/kg every 6 h to a target maintenance dose of 2 mg/kg every 6 h; group 2 received intravenous milrinone 0.5 μg/kg/min as a continuous infusion; and group 3 received both oral sildenafil and intravenous milrinone., Results: Post-treatment pulmonary artery systolic pressure was significantly lower in group 3 than in groups 1 and 2, which both received monotherapy (p = 0.031). The oxygenation index also decreased significantly in the dual-therapy group (p = 0.002) compared with the monotherapy groups. Combined use of both drugs demonstrated a beneficial synergistic effect with better outcomes and reduced mortality., Conclusion: Dual therapy using sildenafil and milrinone was superior to monotherapy with either drug in neonates with severe PPHN and is recommended for use in resource-constrained settings., Registration: Pan African Clinical Trial Registry identifier number PACTR201902691230243.

Signaling pathways, depending on the second messenger molecule cAMP, modulate hippocampal cell signaling via influencing transcription factors like cAMP-regulated element-binding protein (CREB) or early growth response 1 EGR1/Krox24/zif268/ZENK (EGR1). Here, we investigated two reporter cell lines derived from an immortalized hippocampal neuronal cell line stably expressing a CRE- or EGR1-luciferase reporter gene (HT22CREluc and HT22EGR1luc, respectively). The cells were subjected to phosphodiesterase inhibitors and other cAMP-modulating agents to investigate dose- and time-dependent phosphodiesterase (PDE)-mediated fine-tuning of cAMP-dependent transcriptional signaling. The non-isoform-specific cyclic nucleotide phosphodiesterase (PDE) inhibitor isobutyl-methyl-xanthine (IBMX), as well as selective inhibitors of PDE3 (milrinone) and PDE4 (rolipram), were tested for their ability to elevate CRE- and EGR1-luciferase activity. Pharmacological parameters like onset of activity, maximum activity, and offset of activity were determined. In summary, phosphodiesterase inhibition appeared similarly potent in comparison to adenylate cyclase stimulation or direct activation of protein kinase A (PKA) via specific cAMP agonists and was at least partly mediated by PKA as shown by the selective PKA inhibitor Rp -8-Br-cAMPS. Moreover, transcriptional activation by PDE inhibition was also influenced by organic anion-exchanger action and interacted with fibroblast growth factor (FGF) receptor-mediated pathways.

Objective: To compare the effects of milrinone, sodium nitroprusside (SNP), and nitroglycerin (NTG) on induced hypotension, cerebral perfusion, and postoperative cognitive function in elderly patients undergoing spine surgery., Methods: Sixty patients >60 years scheduled for lumbar fusion surgery were assigned to receive milrinone (group M), SNP (group S), or NTG (group N). The administration of the study drug was initiated immediately after perivertebral muscle retraction and was stopped after completion of interbody fusion. Target blood pressure was a decrease of 30% in systolic blood pressure from baseline or mean blood pressure of 60 to 65 mm Hg. The regional cerebral venous oxygen saturation (rSVO2), as a measure of cerebral perfusion, and the change in perioperative Mini-Mental State Examination (MMSE) score, as a measure of postoperative cognitive function, were assessed., Results: During the administration of the study drug, the overall and lowest intraoperative rSVO2 values were significantly higher (P = .01 and P = .01, respectively), and the duration of rSVO2 <60% was shorter in group M than in the other groups (P = .03). In group M, intraoperative rSVO2 was not different from the basal value, whereas in groups S and N, rSVO2 was significantly lower than the basal value during the administration of the study drug, but then returned to the basal value after terminating the study drug. Basal MMSE scores were comparable among the 3 groups. The MMSE score on postoperative day 5 was higher in group M than the other groups., Conclusions: Milrinone used to induce hypotension resulted in better intraoperative cerebral perfusion and postoperative cognitive function compared to SNP and nitroglycerin.

Background: Phosphodiesterase enzymes play a pivotal role in the pathogenesis of ischemia/reperfusion (IR). We examined the role of milrinone (MIL), a phosphodiesterase 3 inhibitor, on remote injury of the heart and lung after abdominal aortic cross-clamping., Design: Experimental study., Methods: Twenty-one Wistar rats were divided into 3 groups: (1) control (C, n = 7), underwent laparotomy and exploration of abdominal aorta only; (2) IR (n = 7), normal saline was applied intraperitoneally (i.p) before IR induced by clamping of the abdominal aorta for 1 hr and then allowing reperfusion for 1 hr; and (3) MIL + IR (n = 7), MIL was given (0.5 mg/kg, i.p) before IR. After sacrification, the lungs and hearts were taken out for analyses and the tissue malondialdehyde (MDA) and glutathione (GSH) were studied. All tissues were examined under light microscopy and transmission electron microscopy (TEM). Expressions of caveolin (Cav)-1 in the lung and Cav-1 and Cav-3 in the heart were examined immunohistochemically., Results: The MIL + IR group had significantly a lower magnitude of oxidative stress than the IR group both in the lung and heart (lung: P = 0.03 for MDA and 0.001 for GSH and heart: P = 0.002 for MDA and 0.000 for GSH). In light microscopy, the MIL + IR group had statistically a lower total injury score than the IR group for both the lung and heart tissue (P = 0.03 and P = 0.04, respectively). In TEM, regression of mitochondrial degeneration and lamellar bodies in type II pneumocytes in the lungs and obvious improvements in disruption at the intercalated discs and mitochondrial degeneration in the hearts in the MIL + IR group were detected compared with the IR group. The expression of both Cav-1 and Cav-3 in the MIL + IR group was improved compared with the IR group (P = 0.03 for both)., Conclusions: MIL attenuates remote injury of heart and lung in lower body IR by inhibiting oxidative stress. Moreover, Cav-1 and Cav-3 might have a potential role in MIL-induced cardioprotection., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Mammalian cyclin A1 is prominently expressed in testis and essential for meiosis in the male mouse, however, it shows weak expression in ovary, especially during oocyte maturation. To understand why cyclin A1 behaves in this way in the oocyte, we investigated the effect of cyclin A1 overexpression on mouse oocyte meiotic maturation. Our results revealed that cyclin A1 overexpression triggered meiotic resumption even in the presence of germinal vesicle breakdown inhibitor, milrinone. Nevertheless, the cyclin A1-overexpressed oocytes failed to extrude the first polar body but were completely arrested at metaphase I. Consequently, cyclin A1 overexpression destroyed the spindle morphology and chromosome alignment by inducing premature separation of chromosomes and sister chromatids. Therefore, cyclin A1 overexpression will prevent oocyte maturation although it can promote meiotic resumption. All these results show that decreased expression of cyclin A1 in oocytes may have an evolutional significance to keep long-lasting prophase arrest and orderly chromosome separation during oocyte meiotic maturation., (© 2020 Wiley Periodicals, Inc.)

Amlexanox, an anti-inflammatory agent, is widely used for treating aphthous ulcers. Recently, amlexanox has received considerable attention because of its efficacy in mitigating metabolic inflammation via directly suppressing IKKε/TBK1. However, because the knockdown of IKKε/TBK1 has no anti-inflammatory effect on lipopolysaccharide (LPS)-primed RAW264.7 cells, the mechanism of amlexanox against classical inflammation is independent of IKKε/TBK1. In this study, we aim to examine the effects of amlexanox on LPS-treated macrophages and in a mouse model of endotoxemia. We found that amlexanox significantly inhibited the production of pro-inflammatory mediators, both in vitro and in vivo, while increased interleukin-10 level in LPS-activated macrophages. Mechanistically, amlexanox down-regulated nuclear factor κB and extracellular signal-regulated kinase/activator protein-1 signaling by elevating intracellular 3',5'-cyclic adenosine monophosphate (cAMP) level and subsequently activating protein kinase A. Molecular docking along with fluorescence polarization and enzyme inhibition assays revealed that amlexanox bound directly to phosphodiesterase (PDE) 4B to inhibit its activity. The anti-inflammatory effects of amlexanox could be abolished by the application of cAMP antagonist or PDE4B siRNA. In addition to PDE4B, the activities of PDE1C, 3A, and 3B were directly inhibited by amlexanox. Our results provide mechanistic insight into the clinical utility of amlexanox for the treatment of inflammatory disorders and might contribute to extending the clinical indications of amlexanox., Competing Interests: Declaration of competing interest None., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: Early postoperative heart failure is common after cardiac surgery, and inotrope treatment may impact renal perfusion and oxygenation. We aimed to study the renal effects of the inodilator milrinone when used for the treatment of heart failure after weaning from cardiopulmonary bypass (CPB)., Material and Methods: In 26 patients undergoing cardiac surgery with CPB, we used renal vein catheterization to prospectively measure renal blood flow (RBF), glomerular filtration rate (GFR), and renal oxygenation. Patients who developed acute heart failure and low cardiac output (cardiac index <2.1 L/min/m 2 ) at 30 min after weaning from CPB (n = 7) were given milrinone, and the remaining patients (n = 19) served as controls. Additional measurements were made at 60 min after CPB., Results: In patients with acute postoperative heart failure, before receiving milrinone, renal blood flow was lower (-33%, p < .05) while renal oxygen extraction was higher (41%, p < .05) compared to the control group. Milrinone increased cardiac index (21%, p < .001), RBF (36%, p < .01) and renal oxygen delivery (35%, p < .01), with no significant change in GFR and oxygen consumption compared to the control group., Conclusions: In patients with acute heart failure after weaning from CPB, the milrinone-induced increase in cardiac output was accompanied by improved renal oxygenation., Trial Registration: ClinicalTrials.gov; identifier NCT02405195, date of registration; March 27, 2015, and NCT02549066, date of registration; 9 September 2015., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2020. Published by Elsevier Inc.)

The objective of this study was to elucidate the underlying cardiotoxic mechanism of milrinone, a cAMP phosphodiesterase 3 inhibitor, by evaluating cardiac functions, blood biomarkers including cardiac troponin I (cTnI), microRNAs (miR-1, miR-133a and miR-499a) and various endogenous metabolites, and histopathology in conscious cynomolgus monkeys. Milrinone at doses of 0, 3 and 30 mg/kg were orally administered to monkeys (n = 3-4/group), and the endpoints were evaluated 1 to 24 h post-dosing. Milrinone caused myocardial injuries characterized by myocardial degeneration/necrosis, cell infiltration and hemorrhage 24 h after drug administration. Cardiac functional analysis revealed that milrinone dose-dependently increased the maximum upstroke velocity of the left ventricular pressure and heart rate, and decreased the QA interval and systemic blood pressure 1-4 h post-dosing, being associated with pharmacological action of the drug. In the blood biomarker analysis, only plasma cTnI was dose-dependently increased 4-7 h after drug administration, suggesting that cTnI is the most sensitive biomarker for early detection of milrinone-induced myocardial injuries. In the metabolomics analysis, high dose of milrinone induced transient changes in lipid metabolism, amino acid utilization and oxidative stress, together with the pharmacological action of increased cAMP and lipolysis 1 h post-dosing before the myocardial injuries were manifested by increased cTnI levels. Taken together, milrinone showed acute positive inotropic and multiple metabolic changes including excessive pharmacological actions, resulting in myocardial injuries. Furthermore, a comprehensive analysis of cardiac functions, blood biomarkers and histopathology can provide more appropriate information for overall assessment of preclinical cardiovascular safety., Competing Interests: Declaration of Competing Interest The authors declare that there is no conflict of interest with respect to the research, authorship and publication of this article., (Copyright © 2020 Elsevier Inc. All rights reserved.)

A simple, quick, easy and cheap tandem mass spectrometry (MS/MS) method for the determination of adenosine monophosphate (AMP) and cyclic adenosine monophosphate (cAMP) has been newly developed. This novel MS/MS method was applied for the evaluation of the inhibitory effect of a novel 2-oxo-1,2-dihydropyridine-3-carbonitrile derivative, also named DF492, on PDE3 enzyme activity in comparison to its parent drug milrinone. Molecule DF492, with an IC 50 of 409.5 nM, showed an inhibition of PDE3 greater than milrinone (IC 50 = 703.1 nM). To explain the inhibitory potential of DF492, molecular docking studies toward the human PDE3A were carried out with the aim of predicting the binding mode of DF492. The presence of different bulkier decorating fragments in DF492 was pursued to shift affinity of this novel molecule toward PDE3A compared to milrinone in accordance with both the theoretical and experimental results. The described mass spectrometric approach could have a wider potential use in kinetic and biomedical studies and could be applied for the determination of other phosphodiesterase inhibitor molecules.

Failure of the normal transition from in utero to ex utero physiology leads to " persistent " pulmonary hypertension of the newborn (PPHN). PPHN is frequently associated with low systemic blood pressure and low cardiac output because of increased right ventricular afterload and myocardial dysfunction. The general management of newborns with PPHN is geared toward maintenance of normothermia, normal serum electrolytes, normal intravascular volume, correction of acidosis, adequate sedation/analgesia, adequate ventilation and oxygenation with optimal lung recruitment, and avoidance of hyperoxia. Inotropic and vasoactive agents are commonly initiated early to increase cardiac output, maintain adequate systemic blood pressure, and enhance oxygen delivery to the tissue. Unfortunately, there is not much evidence on the choice, timing of initiation, dosing, monitoring, and titrating of vasoactive agents in this patient population. In this review, we will discuss the pathophysiology of PPHN and review the use of inotropic, lusitropic, and vasoactive agents in the management of PPHN, with particular attention to milrinone., (Copyright © 2020 by the American Academy of Pediatrics.)

Background: The aim of the present study was to compare the effects of milrinone and levosimendan on right ventricular (RV) inotropy and lusitropy in patients after aortic valve replacement (AVR) for aortic stenosis, a procedure in which an abnormal postoperative RV function may be seen., Methods: In a prospective, blinded trial, 31 patients were randomized to receive either milrinone (0.4 and 0.8 µg/kg/min, n = 16) or levosimendan (0.1 and 0.2 µg/kg/min, n = 15) after AVR for aortic stenosis. RV performance, afterload (pulmonary arterial elastance), RV strain, systolic (SR-S) and early diastolic (SR-E) strain rate were measured by pulmonary artery thermodilution catheterization and transoesophageal two-dimensional speckle tracking echocardiography. To circumvent the indirect effects of inodilator-induced hemodynamic changes on RV systolic and diastolic deformation, pulmonary arterial elastance, central venous pressure and heart rate were maintained constant by atrial pacing, plasma volume expansion with colloids and phenylephrine-induced vasoconstriction during treatment with the inotropes., Results: A dose-dependent increase in stroke volume index and cardiac index by approximately 20% were seen with both agents at the highest doses, with no difference between groups (P = .792 and 0.744, respectively). In both groups, RV strain and SR-S dose-dependently increased by 20% and 15%-19%, respectively, at the highest doses (P = .742 and 0.259, respectively) with no difference between groups. SR-E improved by both agents 20%-24% at the highest dose with no difference between groups (P = .714)., Conclusions: The direct RV inotropic and lusitropic effects of levosimendan and milrinone were comparable at clinically relevant infusion rates., (© 2019 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Milrinone is a drug frequently used for hemodynamic support in children during critical illness. Although the hemodynamic changes induced by milrinone in children may appear similar to those of adults, the physiologic contributors of these changes remain vastly unknown. A systematic review was conducted to identify studies characterising the hemodynamic effects of milrinone in children during critical illness for hemodynamic support for various medical conditions. Studies were assessed for quality and those of satisfactory quality with pre- and post-operative hemodynamics for each patient were included in the final analyses. Those not limited to children and those not limited to patients with critical illness were excluded from the final analyses. A total of six studies with 791 patients were included in the final analyses. Milrinone infusion doses ranged from 0.3 to 0.75 mcg/kg/minute with the mean infusion dose being 0.5 mcg/kg/minute. Patients whom received milrinone infusion had greater cardiac output, greater left ventricle shortening fraction, lower right ventricular systolic pressure, and lower serum lactate levels. Systolic blood pressure mean arterial blood pressure and arterial oxygen concentration did not significantly change with administration of milrinone. These results were irrespective of milrinone infusion dose, infusion duration, and study size. Milrinone was found to have several beneficial hemodynamic effects in children during critical illness when used at usual clinical doses.

Objective: The aim of this study was to investigate the potential protective and therapeutic effects of milrinone, a specific phosphodiesterase (PDE) III inhibitor, on acoustic trauma-induced cochlear injury and apoptosis., Methods: A total number of 30 healthy Wistar albino rats were evenly divided into five groups as follows: group 1 was assigned as control group; group 2 and 3 were assigned as low-dosage groups (0.25 mg/kg) in which milrinone was administered 1 h before acoustic trauma (AT) and 2 h after AT, respectively; group 4 and 5 were assigned as high-dosage groups (0.50 mg/kg) in which the drug was administered 1 h before AT and 2 h after AT, respectively. Except control group, all treatment groups received a single dosage of milrinone for 5 days. Distortion product otoacoustic emissions (DPOAE) measurements were recorded before AT as well as at second and fifth post-traumatic days. At the end of fifth day, all rats were sacrificed and the cochlea of the rats was removed for histopathological evaluation. In addition, the groups were compared in terms of apoptotic index via caspase-3 staining., Results: In terms of signal-to-noise ratio (SNR), there was no statistically significant difference among the groups following AT (p > 0.05). After 5 days of milrinone treatment, the best SNR values were found in group 5, though all groups did not statistically differ (p > 0.05). In histopathological evaluation, vacuolization, inflammation, and edema scores in all treatment groups were statistically lower than those of the control group (p < 0.05). In group 2 and 4 where the drug was administered before AT, the inflammation and apoptosis index was lower than those of group 3 and 5 where the drug was administered after AT (p < 0.0001)., Conclusion: We reveal that milrinone has a protective effect on cochlear damage in the experimental acoustic model of rats. This protective effect was more apparent following the pre-traumatic milrinone administration, and is associated with its effect on decreasing inflammation and apoptosis. Based on DPOAE measurements following AT, especially in the group 5 (high-dosage group), milrinone may also have a therapeutic effect.

Inotropes are an integral component of the early stabilization of the patient presenting with cardiogenic shock. Despite years of clinical experience with the 2 most commonly used inotropes, dobutamine and milrinone, there remains limited data comparing outcomes between the two. We conducted a retrospective review to compare the effectiveness and safety of milrinone or dobutamine for the initial management of cardiogenic shock. Adult patients with cardiogenic shock regardless of etiology who received initial inotrope therapy with either milrinone (n = 50) or dobutamine (n = 50) and did not receive mechanical circulatory support were included. The primary end point was the time to resolution of cardiogenic shock. Changes in hemodynamic parameters from baseline and adverse events were also assessed. Resolution of shock was achieved in similar numbers in both the groups (milrinone 76% vs dobutamine 70%, P = .50). The median time to resolution of shock was 24 hours in both groups ( P = .75). There were no differences in hemodynamic changes during inotrope therapy, although dobutamine trended toward a greater increase in cardiac index. Arrhythmias were more common in patients treated with dobutamine than milrinone, respectively (62.9% vs 32.8%, P < .01), whereas hypotension occurred to a similar extent in both groups (milrinone 49.2% vs dobutamine 40.3%, P = .32). The use of concomitant vasoactive medications, dosage required, and duration of therapy did not differ between groups. There was no difference in the overall rate of discontinuation due to adverse event; however, milrinone was more commonly discontinued due to hypotension (13.1% vs 0%, P < .01) and dobutamine was more commonly discontinued due to arrhythmia (0% vs 11.3%, P < .01). Milrinone and dobutamine demonstrated similar effectiveness and safety profiles but with differences in adverse events. The choice of milrinone or dobutamine as initial inotrope therapy for cardiogenic shock may depend more on tolerability of adverse events.

Caffeine and selective PDE inhibitors are widely used in clinical management of preterm and term neonates. However, little is known about how these compounds interact with the neonatal adaptive immune system. We aimed to describe the effects of caffeine, milrinone and sildenafil on the activation and cytokine production of T cells from umbilical cord blood (UCB) compared to adult peripheral blood (APB). We isolated mononuclear cells from 10 APB and 6 UCB samples. We assessed intracellular cytokine production (IFN-γ, IL-2, IL-4, IL-6, IL-17) of stimulated CD4 cells and parameters of calcium influx and ROS production following treatment with caffeine, milrinone, sildenafil, dbcAMP or a specific A2A receptor antagonist, ZM241385 using flow cytometry. In ABP, only ZM241385 caused a 1.14-fold increase in calcium influx, while all compounds increased calcium influx in UCB. This effect was more pronounced in case of caffeine (1.41-fold) and dbcAMP (1.3-fold) compared to milrinone (1.22-fold), sildenafil (1.23-fold) or ZM241385 (1.23-fold). Intracellular levels of the studied cytokines were unaffected by the applied compounds in both APB and UCB samples. Caffeine increases calcium influx upon activation in neonatal T lymphocytes to a larger extent than milrinone or sildenafil. This effect appears to be mediated primarily via increased cAMP levels rather than A2A receptor inhibition. Overall, the application of caffeine, sildenafil or milrinone does not appear to have immunosuppressive effects on neonatal T cells., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Bovine growing oocytes with a diameter of 105-115 μm from early antral follicles (1.2-1.8 mm) are able to resume meiosis, but lack the competence to mature to metaphase II. To confer full maturation competence onto the oocytes, culture systems which can support their growth and prevent their meiotic resumption during culture are needed. In this study, we cultured growing oocytes for 5 days to examine the effects of different phosphodiesterase (PDE) inhibitors on meiotic arrest and acquisition of full maturation competence of growing oocytes, and their gap junctional communication with cumulus cells. Growing oocyte-cumulus complexes (OCCs) were cultured with 3-isobutyl-1-methylxanthine (IBMX; broad-spectrum PDE inhibitor), rolipram (PDE4D inhibitor), cilostamide and milrinone (PDE3A inhibitors). The mean diameters of oocytes increased similarly in all groups. IBMX, cilostamide and milrinone induced antrum formation by OCCs and maintained meiotic arrest of oocytes during culture, whereas rolipram neither promoted antrum formation nor maintained oocyte meiotic arrest. Gap junctional communication between oocytes and cumulus cells was maintained by IBMX and cilostamide, but not by rolipram as judged by the transfer of injected lucifer yellow dye from oocytes to cumulus cells. In subsequent in vitro maturation, oocytes grown with IBMX, cilostamide and milrinone showed full maturation competence. These results suggest that PDE3A inhibition maintains the meiotic arrest of bovine growing oocytes and sustains their gap junctional communication with cumulus cells for 5 days, thereby contributing to their acquisition of full maturation competence., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Phosphodiesterase 3 (PDE3) exists in two isoforms (PDE3A and PDE3B) and is known to act as cGMP-inhibited cAMP-degrading PDE. Therefore, PDE3 may likely be involved in the interaction between the two second messenger pathways. NO-sensitive guanylyl cyclase (NO-GC) is the most important cytosolic generator of cGMP. Here, we investigated the effect of NO-GC deletion on PDE3A-mediated signaling in animals lacking NO-GC either globally (GCKO) or specifically in smooth muscle cells (SMC-GCKO). PDE3A expression is detected in murine aortic smooth muscle, platelets, and heart tissue. Expression and activity of PDE3A in aortae from GCKO and SMC-GCKO mice was reduced by approx. 50% compared to that in control animals. PDE3A downregulation can be linked to the reduction in NO-GC and is not an effect of the increased blood pressure levels resulting from NO-GC deletion. Despite the different PDE3A expression levels, smooth muscle relaxation induced by forskolin to stimulate cAMP signaling was similar in all genotypes. Basal and forskolin-stimulated cAMP levels in aortic tissue were not different between KO and control strains. However, the potency of milrinone, a selective inhibitor of PDE3A, to induce relaxation was higher in aortae from GCKO and SMC-GCKO than that in aorta from control animals. These data were corroborated by the effect of milrinone in vivo, which led to an increase in systolic blood pressure in both KO strains but not in control mice. We conclude that NO-GC modulates PDE3A expression and activity in SMC in vivo conceivably to preserve functional cAMP signaling.

Phosphodiesterase 3 (PDE3) and PDE4 regulate levels of cyclic AMP, which are critical in various cell types involved in allergic airway inflammation. Although PDE4 inhibition attenuates allergic airway inflammation, reported side effects preclude its application as an antiasthma drug in humans. Case reports showed that enoximone, which is a smooth muscle relaxant that inhibits PDE3, is beneficial and lifesaving in status asthmaticus and is well tolerated. However, clinical observations also showed antiinflammatory effects of PDE3 inhibition. In this study, we investigated the role of PDE3 in a house dust mite-driven (HDM-driven) allergic airway inflammation (AAI) model that is characterized by T helper 2 cell activation, eosinophilia, and reduced mucosal barrier function. Compared with wild-type (WT) littermates, mice with a targeted deletion of the PDE3A or PDE3B gene showed significantly reduced HDM-driven AAI. Therapeutic intervention in WT mice showed that all hallmarks of HDM-driven AAI were abrogated by the PDE3 inhibitors enoximone and milrinone. Importantly, we found that enoximone also reduced the upregulation of the CD11b integrin on mouse and human eosinophils in vitro, which is crucial for their recruitment during allergic inflammation. This study provides evidence for a hitherto unknown antiinflammatory role of PDE3 inhibition in allergic airway inflammation and offers a potentially novel treatment approach.

The spindle assembly checkpoint (SAC) prevents chromosome missegregation by coupling anaphase onset with correct chromosome attachment and tension to microtubules. It does this by generating a diffusible signal from free kinetochores into the cytoplasm, inhibiting the anaphase-promoting complex (APC). The volume in which this signal remains effective is unknown. This raises the possibility that cell volume may be the reason the SAC is weak, and chromosome segregation error-prone, in mammalian oocytes. Here, by a process of serial bisection, we analyzed the influence of oocyte volume on the ability of the SAC to inhibit bivalent segregation in meiosis I. We were able to generate oocytes with cytoplasmic volumes reduced by 86% and observed changes in APC activity consistent with increased SAC control. However, bivalent biorientation remained uncoupled from APC activity, leading to error-prone chromosome segregation. We conclude that volume is one factor contributing to SAC weakness in oocytes. However, additional factors likely uncouple chromosome biorientation with APC activity., (© 2017 Lane and Jones.)

Dobutamine has been used in septic shock for many years as an only inotrope, but its benefit has been questioned. We weighed the effects of dobutamine and milrinone as inotropes in mice with cecal ligation and puncture (CLP)-induced polymicrobial sepsis. CLP-induced septic mice exhibited significant cardiac inflammation, as indicated by greatly increased mRNAs of proinflammatory cytokines and robust infiltration of inflammatory cells in the ventricular myocardium. Elevations of plasma cardiac troponin-I showed cardiac injury in CLP mice. Noninvasive echocardiographic assessment of cardiac function revealed that despite preserved left ventricular function in the presence of fluid replacement, the dobutamine inotropic response was significantly impaired in CLP mice compared with sham-operated controls. By contrast, milrinone exerted inotropic effects in sham-operated and CLP mice in an equally effective manner. Surface expression levels of β 1 -adrenoceptors and α-subunits of three main G protein families in the myocardium were unaffected by CLP-induced sepsis. Plasma cAMP levels were significantly elevated in both sham-operated and CLP mice in response to milrinone but only in sham-operated controls in response to dobutamine. Of phosphodiesterase (PDE) isoforms, PDE4D, but not PDE3A, both of which are responsible for cardiac cAMP hydrolysis, was significantly upregulated in CLP mouse myocardium. We define a novel mechanism for the impaired responsiveness to dobutamine as an inotrope in sepsis, and understanding the role of PDE4D in modulating cardiac functional responsiveness in sepsis may open the potential of a PDE4D-targeted therapeutic option in septic patients with low cardiac output who have a need for inotropic support. NEW & NOTEWORTHY Advisability of the usefulness of dobutamine in septic shock management is limited. Here, we reveal that the effect of dobutamine as a positive inotrope is impaired in mice with cecal ligation and puncture-induced sepsis without changes in cardiac β 1 -adrenoceptor signaling as a result of cAMP breakdown achieved by upregulated phosphodiesterase 4D., (Copyright © 2017 the American Physiological Society.)

Early brain injury/ischaemia (EBI) is a serious complication early after subarachnoid haemorrhage (SAH) that contributes to development of delayed cerebral ischaemia (DCI). This study aimed to determine the role of inotropic cardiac support using milrinone (MIL) on restoring acute cerebral hypoperfusion attributable to EBI and improving outcomes after experimental SAH. Forty-three male C57BL/6 mice were assigned to either sham surgery (SAH-sham), SAH induced by endovascular perforation plus postconditioning with 2% isoflurane (Control), or SAH plus isoflurane combined with MIL with and without hypoxia-inducible factor inhibitor (HIF-I) pretreatment. Cardiac output (CO) during intravenous MIL infusion (0.25-0.75 μg/kg/min) between 1.5 and 2.5 hours after SAH induction was monitored with Doppler echocardiography. Magnetic resonance imaging (MRI)-continuous arterial spin labelling was used for quantitative cerebral blood flow (CBF) measurements. Neurobehavioral function was assessed daily by neurological score and open field test. DCI was analyzed 3 days later by determining infarction on MRI. Mild reduction of cardiac output (CO) and global cerebral blood flow (CBF) depression were notable early after SAH. MIL increased CO in a dose-dependent manner (P<.001), which was accompanied by improved hypoperfusion, incidence of DCI and functional recovery than Control (P<.05). The neuroprotective effects afforded by MIL or Control were attenuated by hypoxia-inducible factor (HIF) inhibition (P<.05). These results suggest that MIL improves acute hypoperfusion by its inotropic effect, leading to neurobehavioral improvement in mice after severe SAH, in which HIF may be acting as a critical mediator., (© 2017 John Wiley & Sons Australia, Ltd.)

Introduction: Load-independent cardiac parameters obtained from the ventricular pressure-volume relationship are recognized as gold standard indexes for evaluating cardiac inotropy. In this study, for better analyses of cardiac risks, load-independent pressure-volume loop parameters were assessed in addition to load-dependent inotropic, hemodynamic and electrocardiographic changes in isoflurane-anesthetized monkeys., Methods: The animals were given milrinone (a PDE 3 inhibitor), metoprolol (a β-blocker), or dl-sotalol (a β+I Kr blocker) intravenously over 10min at two dose levels including clinically relevant doses (n=5/drug)., Results: Milrinone and metoprolol produced positive and negative inotropy, respectively. These effects were detected as changes in the slope of the preload-recruitable stroke work, which is a load-independent inotropic parameter. However, dl-sotalol did not alter the slope of the preload-recruitable stroke work. That means dl-sotalol produced no inotropy, although it decreased load-dependent inotropic parameters, including maximal upstroke velocity of left ventricular pressure, attributable to decreased heart rate and blood pressure. Other typical pharmacological effects of the compounds tested were also detected. Both β-blockers produced PR prolongation, decreased left ventricular end-systolic pressure, increased left ventricular end-diastolic pressure, and increased maximal descending velocity of left ventricular pressure and time constant for isovolumic relaxation. dl-Sotalol also prolonged heart-rate-corrected QT interval. Milrinone induced reflex tachycardia, PR shortening, and decreased left ventricular end-diastolic pressure., Discussion: The overall assessment by not only load-dependent inotropic parameters but also load-independent parameters obtained from the ventricular pressure-volume loop analysis using monkeys can provide further appropriate information for the assessment of drug-induced cardiac risks., (Copyright © 2016 Elsevier Inc. All rights reserved.)

In an attempt to search for more potent positive inotropic agents, two series of [1,2,4]triazolo[4,3- a ] quinoxaline derivatives bearing substituted benzylpiperazine and benzoylpiperazine moieties were synthesized and their positive inotropic activities evaluated by measuring left atrial stroke volume in isolated rabbit heart preparations. Several compounds showed favorable activities compared with the standard drug, milrinone. Compound 6c was the most potent agent, with an increased stroke volume of 12.53% ± 0.30% (milrinone: 2.46% ± 0.07%) at 3 × 10 -5 M. The chronotropic effects of compounds having considerable inotropic effects were also evaluated.

Juvenile in vitro embryo transfer is a novel technique that can be used to increase the rate of genetic gain in a population and presents an alternative to embryo technologies on the basis of adult animals. However, oocytes from prepubertal animals have a lower viability than those obtained from adult ewe oocyte donors. In this research, we aimed to determine the optimum concentration and time of treatment of oocytes from prepubertal lambs with brilliant cresyl blue (BCB) stain and milrinone during IVM. This would improve the developmental rate of lamb oocytes and embryos after IVF. First, lamb cumulus-oocyte complexes were cultured under different concentrations (13 or 26 μM) of BCB staining. Treated lamb oocytes were then divided into BCB- (colorless cytoplasm) and BCB+ (colored cytoplasm) groups on the basis of their glucose-6-phosphate dehydrogenase activity. The blastocyst efficiency rate of BCB+ oocytes treated with 13 μM BCB (37.03%) was significantly higher than that of BCB+ oocytes treated with 26 μM BCB (23.25%) and that of nontreated BCB control oocytes (15.37%), as well as that of BCB- oocytes (6.28%). Both control oocytes and BCB+ oocytes exhibited significantly higher cleavage rates (60.15% and 73.44%, respectively) than that of BCB- oocytes (36.19%). Moreover, the diameter and glutathione content of BCB+ oocytes were found to be significantly greater than those of BCB- oocytes (163.37 vs. 159.25 μm and 6.39 vs. 0.26 pM, respectively). After culturing BCB- oocytes in different concentrations of milrinone (0, 50, 75, and 100 μM) for 3, 6, or 9 hours, results reported that supplementation of IVM medium with 75 μM milrinone for 6 hours yielded a significantly higher proportion of blastocysts than the other treatments. These results show that the staining of lamb cumulus-oocyte complexes with 13 μM BCB before IVM may be used to select developmentally competent lamb oocytes. Furthermore, they suggest that milrinone can be used to promote lamb developmental competence of lamb embryos produced during IVF., (Copyright © 2016 Elsevier Inc. All rights reserved.)

It is not known whether there are positive or negative interactions on ventricular function when a calcium-sensitizing inotrope is added to a phosphodiesterase inhibitor in the clinical setting of acute left ventricular (LV) dysfunction. We hypothesized that when levosimendan is added to milrinone treatment, there will be synergetic inotropic and lusitropic effects. This was tested in an anesthetized porcine postischemic global LV injury model, where ventricular pressures and volumes (conductance volumetry) were measured. A global ischemic injury was induced by repetitive left main stem coronary artery occlusions. Load-independent indices of LV function were assessed before and after ventricular injury, after milrinone treatment, and finally after addition of levosimendan to the milrinone treatment. Nonparametric, within-group comparisons were made. The protocol was completed in 12 pigs, 7 of which received the inotrope treatment and 5 of which served as controls. Milrinone led to positive lusitropic effects seen by improvement in tau after myocardial stunning. The addition of levosimendan to milrinone further increased lusitropic state. The latter effect could however not be attributed solely to levosimendan, since lusitropic state also improved spontaneously in time-matched controls at the same rate during the corresponding period. When levosimendan was added to milrinone infusion, there was no increase in systolic function (preload recruitable stroke work) compared to milrinone treatment alone. We conclude that in this model of postischemic LV dysfunction, there appears to be no clear improvement in systolic or diastolic function after addition of levosimendan to established milrinone treatment but also no negative effects of levosimendan in this context., (© The Author(s) 2016.)

Inotropic medications are routinely used to increase cardiac output and arterial blood pressure during critical illness. However, few comparative data exist between these medications, particularly independent of their effects on venous capacitance and systemic vascular resistance. We hypothesized that an isolated working heart model that maintained constant left atrial pressure and aortic blood pressure could identify load-independent differences between inotropic medications. In an isolated heart preparation, the aorta and left atrium of Sprague Dawley rats were cannulated and placed in working mode with fixed left atrial and aortic pressure. Hearts were then exposed to common doses of a catecholamine (dopamine, epinephrine, norepinephrine, or dobutamine), milrinone, or triiodothyronine (n = 10 per dose per combination). Cardiac output, contractility (dP/dtmax), diastolic performance (dP/dtmin and tau), stroke work, heart rate, and myocardial oxygen consumption were compared during each 10-min infusion to an immediately preceding baseline. Of the catecholamines, dobutamine increased cardiac output, contractility, and diastolic performance more than clinically equivalent doses of norepinephrine (second most potent), dopamine, or epinephrine (P < 0.001). The use of triiodothyronine and milrinone was not associated with significant changes in cardiac output, contractility or diastolic function, either alone or added to a baseline catecholamine infusion. Myocardial oxygen consumption was closely related to dP/dtmax (r(2) = 0.72), dP/dtmin (r(2) = 0.70), and stroke work (r(2) = 0.53). In uninjured, isolated working rodent hearts under constant ventricular loading conditions, dobutamine increased contractility and cardiac output more than clinically equivalent doses of norepinephrine, dopamine, and epinephrine; milrinone and triiodothyronine did not have significant effects on contractility., (Copyright © 2016 the American Physiological Society.)

Background: Early repolarization syndrome (ERS) is associated with polymorphic ventricular tachycardia (PVT) and ventricular fibrillation, leading to sudden cardiac death., Objective: The present study tests the hypothesis that the transient outward potassium current (Ito)-blocking effect of phosphodiesterase-3 (PDE-3) inhibitors plays a role in reversing repolarization heterogeneities responsible for arrhythmogenesis in experimental models of ERS., Methods: Transmembrane action potentials (APs) were simultaneously recorded from epicardial and endocardial regions of coronary-perfused canine left ventricular (LV) wedge preparations, together with a transmural pseudo-electrocardiogram. The Ito agonist NS5806 (7-15 μM) and L-type calcium current (ICa) blocker verapamil (2-3 μM) were used to induce an early repolarization pattern and PVT., Results: After stable induction of arrhythmogenesis, the PDE-3 inhibitors cilostazol and milrinone or isoproterenol were added to the coronary perfusate. All were effective in restoring the AP dome in the LV epicardium, thus abolishing the repolarization defects responsible for phase 2 reentry and PVT. Arrhythmic activity was suppressed in 7 of 8 preparations by cilostazol (10 μM), 6 of 7 by milrinone (2.5 μM), and 7 of 8 by isoproterenol (0.1-1 μM). Using voltage clamp techniques applied to LV epicardial myocytes, both cilostazol (10 μM) and milrinone (2.5 μM) were found to reduce Ito by 44.4% and 40.4%, respectively, in addition to their known effects to augment ICa., Conclusion: Our findings suggest that PDE-3 inhibitors exert an ameliorative effect in the setting of ERS by producing an inward shift in the balance of current during the early phases of the epicardial AP via inhibition of Ito as well as augmentation of ICa, thus reversing the repolarization defects underlying the development of phase 2 reentry and ventricular tachycardia/ventricular fibrillation., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

We demonstrated that in human platelets the endocannabinoid 2-arachidonoylglycerol (2-AG) decreased dose- and time-dependently cAMP intracellular levels. No effect on cAMP decrease induced by 2-AG was observed in the presence of the adenylate cyclase inhibitor SQ22536 as well in platelets pretreated with the thromboxane A2 receptor antagonist, SQ29548 or with aspirin, inhibitor of arachidonic acid metabolism through the cyclooxygenase pathway. An almost complete recovering of cAMP level was measured in platelets pretreated with the specific inhibitor of phosphodiesterase (PDE) 3A, milrinone. In platelets pretreated with LY294002 or MK2206, inhibitors of PI3K/AKT pathway, and with U73122, inhibitor of phospholipase C pathway, only a partial prevention was shown. cAMP intracellular level depends on synthesis by adenylate cyclase and hydrolysis by PDEs. In 2-AG-stimulated platelets adenylate cyclase activity seems to be unchanged. In contrast PDEs appear to be involved. In particular PDE3A was specifically activated, as milrinone reversed cAMP reduction by 2-AG. 2-AG enhanced PDE3A activity through its phosphorylation. The PI3K/AKT pathway and PKC participate to this PDE3A phosphorylation/activation mechanism as it was greatly inhibited by platelet pretreatment with LY294002, MK2206, U73122, or the PKC specific inhibitor GF109203X. Taken together these data suggest that 2-AG potentiates its power of platelet agonist reducing cAMP intracellular level., (© 2015 Wiley Periodicals, Inc.)