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Objective: High-pressure physiological saline isotonic solution (HPpSIS) delivery into the nasal cavity was found to modulate the local expression of immune cells, increase NGF protein, and enhance the NGF receptors' expression. Since the nasal cavity directly communicates with the eye and as NGF was previously found to ameliorate the symptoms of dry eye when topically delivered, the aim of this study was to establish whether the HPpSIS might ameliorate ocular dryness and tear film composition., Subjects and Methods: This is an observational self-controlled case study carried out on 16 patients with dry-eye diagnosis, concerning 3-month self-administration of HPpSIS and two serial assessments of the ocular surface and tear film. OSDI questionnaire was used for ocular symptoms of dryness. BUT and Schirmer tests were used for qualitative and quantitative tear film analysis. The lipid composition was also examined. R-studio was employed for the detection of the difference between the pre- and post-analysis., Results: On the basis of the OSDI questionnaire, the study population was divided into severe (61.1%), moderate (5.5%), and mild (16.6%) dry-eye symptoms. OSDI score was significantly reduced after HPpSIS (p<0.05). BUT and TMH values also ameliorated after HPpSIS (p>0.05), although not significantly. The lipid layer improved statistically (p<0.05) and correlated positively with OSDI grading. The variability of presentation in the numerical distribution before and after therapy suggests poor test sensitivity., Conclusions: HPpSIS showed a positive effect in reducing OSDI scores and ameliorating tear film quality. The possibility of an endogenous HPpSIS-induced NGF should be taken into account in dry-eye therapy.

Background: Normal saline or lactated Ringer's solutions are usually infused at the time of fetal interventions; however, the effect of these fluids on the amniotic membranes has never been assessed. Given both the significant differences between the composition of normal saline solution, lactated Ringer's solution, and amniotic fluid and the significant risk of prematurity after fetal interventions, an investigation is warranted., Objective: This study aimed to evaluate the effect of current amnioinfusion fluids on the human amnion compared with a novel synthetic amniotic fluid., Study Design: Amniotic epithelial cells from term placentas were isolated and cultured per protocol. A synthetic amniotic fluid was created with similar electrolyte, pH, albumin, and glucose concentrations to human amniotic fluid, termed "Amnio-well." The cultured human amniotic epithelium was exposed to normal saline solution, lactated Ringer's solution, and Amnio-well. As a control, 1 group of cells remained in culture media. Cells were evaluated for apoptosis and necrosis. A second analysis to examine if cells could be "rescued" was performed, wherein the cells were allowed to remain in the culture media for an additional 48 hours after amnioinfusion. Subsequently, tissue testing with human amniotic membrane explants was evaluated similarly. Immunofluorescent intensity studies were undertaken to evaluate reactive oxygen species-mediated cell damage. Real-time quantitative polymerase chain reaction was used to evaluate gene expression in apoptotic pathways., Results: With simulated amnioinfusion, 44%, 52%, and 89% of amniotic epithelial cells were alive after exposure to normal saline solution, lactated Ringer's solution, and Amnio-well, respectively, compared with 85% in control (P<.001). After amnioinfusion and attempted cell rescue, 21%, 44%, 94%, and 88% of cells were alive after exposure to normal saline solution, lactated Ringer's solution, Amnio-well, and control, respectively (P<.001). In simulated amnioinfusion with full-thickness tissue explants, 68%, 80%, 93%, and 96% of cells were viable in normal saline solution, lactated Ringer's solution, Amnio-well, and control, respectively (P<.001). In culture, reactive oxygen species production was higher in normal saline solution, lactated Ringer's solution, and Amnio-well than in control (4.9-, 6.6-, and 1.8-fold higher, respectively, P<.001); however, this could be mitigated in Amnio-well by adding ulin-A-statin and ascorbic acid. Gene expression data revealed abnormal signaling in the p21 and BCL2/BAX pathways with normal saline solution compared with control (P=.006 and P=.041); changes were not seen with Amnio-well., Conclusion: In vitro, normal saline and lactated Ringer's solutions caused increased amniotic membrane reactive oxygen species and cell death. The use of a novel fluid similar to human amniotic fluid led to the normalization of cellular signaling and less cell death., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Serotonin, which is a vasoactive amine, is an important neurotransmitter and is involved in many behavioral and psychological phenomena, such as pain, appetite, mood, and sleep. The primary purpose of our study was to investigate the effect of high-pressure administration of sterile physiological saline isotonic solution (HpPSIS) into nasal cavity and to determine the expression of the serotonin., Patients and Methods: The study was made in two branches, the previous with 14 volunteers, the subsequent study with 40 patients with mild anxiety disorder. The middle third of the inferior turbinate epithelial cells on the right nostril was scraped using a sterile curette and indicated as (pre), then, a spray of sterilized isotonic solution at high pressure on the left nostril was delivered, and 5 minutes later a similar stimulation was delivered on the same nostril. The stimulation was made with a specific spray dispenser. The middle third of the inferior turbinate epithelial cells on the left nostril was scraped using a sterile curette and indicated as (post). Then, based on the first part of our study, we started the second part and gave a treatment on forty new patients with anxiety disorder., Results: The results of these studies highlight the possibility of endogenous enhancement of serotonin by stimulation of mast cells. In the first part of the study, Serotonin significantly increased in protein extracts after treatment (64.35±5.33 vs. 10.97±2.17; unpaired two tailed t-test, t=9.8, df=24, p≤0.0001; F=6.035; DFn=12; DFd=12). In the second part of the study, in patients treated with HpPSIS, we observed improvement of mood, after one, two and three months, with a statistically significant reduction of DASS-21, while no reduction was observed in control patients, treated with normal pressure commercial spray., Conclusions: This pilot study showed that the topical treatment of HpPHIS increases serotonin levels in nasal cavity. The observation reported in this study opens the way to a new valid strategy to enhance the level of endogenous serotonin. We observed a significant improvement of ASI on patients during HpPHIS therapy.

Background: Recent trials have suggested use of balanced crystalloids may decrease the incidence of major adverse kidney events compared to saline in critically ill adults. The effect of crystalloid composition on biomarkers of early acute kidney injury remains unknown., Methods: From February 15 to July 15, 2016, we conducted an ancillary study to the Isotonic Solutions and Major Adverse Renal Events Trial (SMART) comparing the effect of balanced crystalloids versus saline on urinary levels of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) among 261 consecutively-enrolled critically ill adults admitted from the emergency department to the medical ICU. After informed consent, we collected urine 36 ± 12 h after hospital admission and measured NGAL and KIM-1 levels using commercially available ELISAs. Levels of NGAL and KIM-1 at 36 ± 12 h were compared between patients assigned to balanced crystalloids versus saline using a Mann-Whitney U test., Results: The 131 patients (50.2%) assigned to the balanced crystalloid group and the 130 patients (49.8%) assigned to the saline group were similar at baseline. Urinary NGAL levels were significantly lower in the balanced crystalloid group (median, 39.4 ng/mg [IQR 9.9 to 133.2]) compared with the saline group (median, 64.4 ng/mg [IQR 27.6 to 339.9]) (P < 0.001). Urinary KIM-1 levels did not significantly differ between the balanced crystalloid group (median, 2.7 ng/mg [IQR 1.5 to 4.9]) and the saline group (median, 2.4 ng/mg [IQR 1.3 to 5.0]) (P = 0.36)., Conclusions: In this ancillary analysis of a clinical trial comparing balanced crystalloids to saline among critically ill adults, balanced crystalloids were associated with lower urinary concentrations of NGAL and similar urinary concentrations of KIM-1, compared with saline. These results suggest only a modest reduction in early biomarkers of acute kidney injury with use of balanced crystalloids compared with saline., Trial Registration: ClinicalTrials.gov number: NCT02444988 . Date registered: May 15, 2015.

Disturbed homeostasis of nitric oxide (NO) is one of the causes of myocardial ischemia/reperfusion (I/R) injury during open-heart surgery. This study was designed to explore mechanisms of action of dinitrosyl iron complexes with reduced glutathione ({(GS - ) 2 Fe + (NO + ) 2 } + , DNIC-GS) added to crystalloid cardioplegia or reperfusion solution in isolated working rat hearts. Hearts of male Wistar rats were subjected to cardioplegic arrest by St. Thomas' Hospital cardioplegic solution (STH) and normothermic global ischemia followed by reperfusion. DNIC-GS were used with STH or during early reperfusion. Lactate dehydrogenase (LDH) activity in the coronary effluent and myocardial contents of adenine nucleotides, phosphocreatine, and lactate were determined spectrophotometrically. Reactive oxygen species (ROS) formation in the coronary effluent and myocardial DNIC content was assessed by EPR technique. Cardioplegia or reperfusion with DNIC-GS significantly improved recovery of coronary flow and cardiac function compared with control. Carboxy-[2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidozoline-1-oxy-3-oxide] (C-PTIO), a selective NO scavenger, reduced/abolished protective action of DNIC-GS. Enhanced recovery of cardiac function with DNIC-GS reduced LDH release in the coronary effluent, augmented recovery of myocardial energy state, and decreased formation of ROS-generating systems at reperfusion. Beneficial effects of DNIC-GS were related to the transfer of [Fe(NO) 2 ] cores to thiol groups of myocardial proteins to form intracellular DNIC pools. The study concluded that DNIC-GS is a promising adjunct agent for metabolic and antioxidant protection of the heart during cardioplegic arrest and reperfusion.

Objective: To determine whether a restrictive perioperative fluid management in the context of an enhanced recovery after surgery program for radical cystectomy and urinary diversion affects renal function, as fluid restriction and the use of vasopressors have been linked to impaired tissue perfusion, potentially resulting in renal dysfunction., Methods: We followed 166 patients initially included in a randomized clinical trial and equally allocated to receive a continuous norepinephrine administration combined with 1ml/kg/h initially, and after cystectomy 3ml/kg/h crystalloid infusion (intervention group, n = 83), or a standard crystalloid infusion of 6ml/kg/h throughout surgery (control group, n = 83). All patients followed our institutional enhanced recovery after surgery program. We prospectively assessed renal function (plasma creatinine values and estimated glomerular filtration rate Chronic Kidney Disease Epidemiology Collaboration equation) postoperatively. Decreased renal function was defined as a decrease in glomerular filtration rate is greater than 20% compared to preoperative values., Results: There was no significant difference in renal function between the groups postoperatively at any time point after discharge: diabetes mellitus (HR = 2.81 [95% CI: 1.48-5.36]; P = 0.002), preoperative estimated glomerular filtration rate (HR = 1.02 [95% CI: 1.00-1.03]; P = 0.007), and age (OR = 1.03 [95% CI: 11.00-1.06]; P = 0.038) were negative predictors for renal deterioration., Conclusion: Postoperative renal function evolution was similar in patients receiving restrictive hydration with norepinephrine administration when compared to liberal hydration intraoperatively, suggesting that there is no influence of fluid management and administration of vasopressors on mid-term renal function., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Maintenance of corneal hydration is dependent on the active transport properties of the corneal endothelium. We tested the hypothesis that lactic acid efflux, facilitated by buffering, is a component of the endothelial fluid pump. Rabbit corneas were perfused with bicarbonate-rich (BR) or bicarbonate-free (BF) Ringer of varying buffering power, while corneal thickness was measured. Perfusate was collected and analyzed for lactate efflux. In BF with no added HEPES, the maximal corneal swelling rate was 30.0 ± 4.1 μm/h compared with 5.2 ± 0.9 μm/h in BR. Corneal swelling decreased directly with [HEPES], such that with 60 mM HEPES corneas swelled at 7.5 ± 1.6 μm/h. Perfusate [lactate] increased directly with [HEPES]. Similarly, reducing the [HCO3 (-)] increased corneal swelling and decreased lactate efflux. Corneal swelling was inversely related to Ringer buffering power (β), whereas lactate efflux was directly related to β. Ouabain (100 μM) produced maximal swelling and reduction in lactate efflux, whereas carbonic anhydrase inhibition and an monocarboxylic acid transporter 1 inhibitor produced intermediate swelling and decreases in lactate efflux. Conversely, 10 μM adenosine reduced the swelling rate to 4.2 ± 0.8 μm/h and increased lactate efflux by 25%. We found a strong inverse relation between corneal swelling and lactate efflux (r = 0.98, P < 0.0001). Introducing lactate in the Ringer transiently increased corneal thickness, reaching a steady state (0 ± 0.6 μm/h) within 90 min. We conclude that corneal endothelial function does not have an absolute requirement for bicarbonate; rather it requires a perfusing solution with high buffering power. This facilitates lactic acid efflux, which is directly linked to water efflux, indicating that lactate flux is a component of the corneal endothelial pump., (Copyright © 2016 the American Physiological Society.)

The aim of this in-vitro study was to evaluate haemostasis analysed with thromboelastometry and blood gas and blood count variables, in stored blood components and the effects after dilution with Ringer[Combining Acute Accent]s acetate, albumin and hydroxyethyl starch (HES). Aliquots from stored red blood cells, plasma and platelet concentrates were mixed in the proportion of 4 : 4 : 1 and analysed with rotational thromboelastometry (ROTEM), blood count [haemoglobin (Hb), haematocrit, platelet count] and blood gas (pH, calcium, sodium, potassium, glucose levels). The blood mix was thereafter diluted 20 and 33% with Ringer's acetate, albumin or HES. The stored blood component mix in a ratio of 4 : 4 : 1 had a low pH (7.11 ± 0.03, mean ± standard deviation), nonmeasurable calcium level, and high concentrations of sodium, potassium and glucose but ROTEM curves within normal range after recalcification. With Ringer's acetate dilution, the ROTEM variables changed almost linearly with increasing dilution volume. When albumin was used in the 33% dilution, the clot firmness of the fibrin clot (FibTEM) was further reduced, and with HES dilution, there was a pronounced impairment. The stored blood mix had a low pH and calcium level, both of which might have a significant influence on the coagulation process but normal ROTEM curves after recalcification. Dilution with Ringer's acetate and albumin resulted in moderate deterioration, while dilution with HES showed severely impaired haemostasis.

Hyperpolarized (13)C MR measurements have the potential to display non-linear kinetics. We have developed an approach to describe possible non-first-order kinetics of hyperpolarized [1-(13)C] pyruvate employing a system of differential equations that agrees with the principle of conservation of mass of the hyperpolarized signal. Simultaneous fitting to a second-order model for conversion of [1-(13)C] pyruvate to bicarbonate, lactate and alanine was well described in the isolated rat heart perfused with Krebs buffer containing glucose as sole energy substrate, or glucose supplemented with pyruvate. Second-order modeling yielded significantly improved fits of pyruvate-bicarbonate kinetics compared with the more traditionally used first-order model and suggested time-dependent decreases in pyruvate-bicarbonate flux. Second-order modeling gave time-dependent changes in forward and reverse reaction kinetics of pyruvate-lactate exchange and pyruvate-alanine exchange in both groups of hearts during the infusion of pyruvate; however, the fits were not significantly improved with respect to a traditional first-order model. The mechanism giving rise to second-order pyruvate dehydrogenase (PDH) kinetics was explored experimentally using surface fluorescence measurements of nicotinamide adenine dinucleotide reduced form (NADH) performed under the same conditions, demonstrating a significant increase of NADH during pyruvate infusion. This suggests a simultaneous depletion of available mitochondrial NAD(+) (the cofactor for PDH), consistent with the non-linear nature of the kinetics. NADH levels returned to baseline following cessation of the pyruvate infusion, suggesting this to be a transient effect., (© 2016 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)

Objective: Pyruvate can reduce lipid peroxidation, which plays a critical role in organ injury, in various models. However, it is not fully understood if this inhibition occurs in resuscitation of hemorrhagic shock (HS). This study examines effects of pyruvate Ringer solution (PR) in this respect in rats., Methods: Rats, subjected to 45% blood loss, were randomly allocated to the 3 groups (n = 18): HS with no fluid resuscitation (group NR), HS resuscitated with lactated Ringer solution (LR) (group LR), and HS resuscitated with PR (group PR). Mean arterial pressure, plasma levels of thiobarbituric acid reactive substances (TBARS), and superoxide dismutase were measured at various time points until 360 minutes after hemorrhage. Visceral organs were harvested at the end for evaluations of the TBARS, antioxidant enzyme, and tissue water content. Other 54 rats with identical procedures without sampling were documented for 24-hour survival rates (n = 18) after fluid resuscitation., Results: Pyruvate Ringer solution significantly increased mean arterial pressure and decreased blood TBARS levels after lethal HS. It also reduced TBARS concentrations and glutathione peroxidase activities but significantly enhanced glutathione reductase activities in most organs and greatly improved the ratios of reduced glutathione over oxidized glutathione in various organs in group PR, compared to group LR. Furthermore, PR significantly improved various organ function and water contents relative to LR. Group PR showed a more than 2-fold higher 24-hour survival rate of group LR., Conclusions: Pyruvate Ringer solution alleviated organ edema and injury and prompted survival partially through inhibition of lipid peroxidation in various organs in severe HS rats., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Crystalloid podocytopathy with focal segmental glomerulosclerosis in plasma cell myeloma (PCM) is rare., Case Presentation: We present a case of crystalline deposition in the bone marrow (BM) and various renal cells with only proteinuria as a symptom. As workup for proteinuria, a renal biopsy sample was obtained. EM showed multiple crystalline depositions in renal tubular cells and podocytes. Focal segmental glomerulosclerosis with crystalloid podocytopathy was diagnosed. Because monoclonal gammopathy was detected in the serum and urine, a BM study was also performed. Plasma cells with needle-shaped inclusion bodies were observed. The crystalline deposits in the plasma cells and podocytes were positive for Masson's trichrome and kappa light-chain staining. These findings indicated that the crystalline deposits originated from paraprotein. The case showed a rare process of focal segmental glomerulosclerosis via crystalline deposition in podocytes in plasma cell myeloma., Conclusions: Crystalloid podocytopathy is a likely cause of renal damage such as FSGS in PCM, although it is an uncommon mechanism for myeloma kidney.

Guanylin (GN) action on seawater eel intestine was examined under simulated in vivo conditions, where isotonic luminal fluid has low NaCl and high MgSO4 (MgSO4 Ringer). In Ussing chamber, MgSO4 Ringer induced serosa-negative potential difference (PD) even after bumetanide treatment, which is due to the higher paracellular Na(+) permeability over Cl(-), as confirmed by the replacement by MgCl2 (no Cl(-) gradient) or Na2SO4 Ringer (no Na(+) gradient). Luminal GN reversed serosa-negative PD, probably by enhancing Cl(-) secretion into the lumen, as the GN effect was blocked by apical Cl(-) channel blockers [diphenylamine-2-carboxylic acid (DPC), 5-nitro-2-(3-phenylpropylamino) benzoic acid, glibenclamide but not cystic fibrosis transmembrane regulator (CFTR)inh-172] or replacement of luminal fluid by MgCl2 Ringer. The blockers' effect was undetectable when normal Ringer was on both sides. In the sac preparation, NaCl secretion occurred into the lumen (Na(+) > Cl(-)), and GN further enhanced Cl(-) secretion (Cl(-) > Na(+)), resulting in water secretion. These GN effects were also blocked by DPC. Quantitative analyses showed that isotonic NaCl is absorbed when luminal fluid is normal Ringer, but, when luminal fluid is MgSO4 Ringer, hypertonic NaCl, almost equivalent to seawater, is secreted into the lumen after GN. These results indicate that GN stimulates the secretion of hypertonic NaCl into the lumen of seawater eel intestine, like rectal gland of marine elasmobranchs, to get rid of excess NaCl although marine teleost intestine is thought to have only absorptive-type cells with a unique Na-K-Cl cotransport system. The secreted NaCl may activate the cotransport system and further help absorb water in the final segment of seawater eel intestine., (Copyright © 2015 the American Physiological Society.)

Plant macroautophagy is carried out by autophagosome-type organelles. Recent evidence suggests that plastids also can carry out macroautophagy. The double membrane at the surface of plastids apparently invaginates, forming an intraplastidial space. This space contains a portion of cytoplasm that apparently becomes degraded. Here we report, in Tillandsia sp. and Aechmaea sp., the presence of almost square or diamond-shaped crystalloids inside what seems the intraplastidial space of autophagous plastids. The same type of crystalloids were observed in chloroplasts and other plastids, but were not found in the cytoplasm or the vacuole. Peroxisomes contained smaller and more irregularly shaped crystalloids compared to the ones observed in 'autophagous' plastids. It is hypothesized that plastids are able to sequester chloroplasts and other plastids., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Objective: To find the appropriate type of intravenous fluid (isotonic vs. hypotonic saline in 5 % dextrose) for empiric maintenance fluid therapy in children with central nervous system (CNS) infections that reduces the incidence of hospital acquired hyponatremia., Methods: This blinded randomized controlled trial included hospitalized children aged 3 mo to 5 y with suspected CNS infections requiring intravenous maintenance fluid for at least 24 h. The subjects were randomized to receive 0.9 % saline (Group-A), 0.45 % saline (Group-B) and 0.18 % saline (Group-C) at standard maintenance rate. The outcome measures were proportion of patients developing hyponatremia (serum sodium < 135 mmol/L) after 24 h and serum sodium values at 6, 12, 18, 24 h of receiving maintenance fluids., Results: Of the 92 patients enrolled, 31, 30 and 31 patients were randomized to Group A, B and C, respectively. Majority (60.7 %) of the patients in Group-C developed hyponatremia compared with 7.1 % of the children in Group-A and 46.1 % in Group-B. During first 24 h of fluid administration successive fall in the serum sodium values was observed in patients receiving hypotonic fluids. The risk of developing hyponatremia was nearly 6½ (95 % confidence interval (CI) 1.6-26) to 8.5 (95 % CI 2.16-33.39) times more in patients who received hypotonic saline compared to those who received isotonic saline., Conclusions: Administration of 0.9 % saline in 5 % dextrose as intravenous maintenance fluid in children with CNS infection leads to significantly less incidence of hyponatremia when compared to that with hypotonic fluids.

The current trend in anaesthesia is to choose crystalloid over colloid fluids for volume replacement in the operating room. Outcome-oriented studies and kinetic analyses have recently provided more insight into how crystalloid infusions should be managed. These fluids have a much better short-term effect on the plasma volume than previously believed. Their efficiency (i.e. the plasma volume expansion divided by the infused volume) is 50-80% as long as an infusion continues, while this fraction increases to 100% when the arterial pressure has dropped. Elimination is very slow during surgery, and amounts to only 10% of that recorded in conscious volunteers. Capillary refill further reduces the need for crystalloid fluid when bleeding occurs. These four factors limit the need for large volumes of crystalloid fluid during surgery. Adverse effects associated with crystalloid fluids mainly include prolonged gastrointestinal recovery time, which occurs when > 3 L has been infused. Clinicians who do not want to prolong the length of the hospital stay by 1-2 days due to such problems may use colloid fluid selectively, but calculations show that the therapeutic window for colloids is quite narrow. Inflammation is likely to decrease the fluid efficiency of colloid fluids, while its effect on crystalloids is unclear. However, some recent evidence suggests that inflammation accelerates the turnover of crystalloid fluid as well.

Background: It is believed that the effectiveness of colloids as plasma volume expanders is dependent on the endothelial permeability for macromolecules. The objective of this study was to test the hypothesis that the plasma volume expanding effect of 5% albumin relative to that of a crystalloid solution is reduced if microvascular permeability is increased., Methods: A control group was resuscitated with either 5% albumin (8 ml/kg) or Ringer's acetate (36 ml/kg) immediately after a hemorrhage of 8 ml/kg (n = 29). In a second group, permeability was increased by inducing sepsis through cecal ligation and incision (n = 28). Three hours after cecal ligation and incision, the animals were resuscitated with either 5% albumin in a ratio of 1:1 relative to the volume of lost plasma, or Ringer's acetate in a ratio of 4.5:1., Results: In the hemorrhage group, plasma volumes at 15 min after resuscitation with albumin or Ringer's acetate had increased by 9.8 ± 2.6 ml/kg (mean ± SD) and 7.4 ± 2.9 ml/kg and were similar at 2 and 4 h. Plasma volume 3 h after cecal ligation and incision had decreased by approximately 7 ml/kg, and at 15 min after resuscitation with albumin or Ringer's acetate it had increased by 5.7 ± 2.9 and 2.4 ± 3.0 ml/kg, respectively (P < 0.05). At 2 and 4 h after resuscitation, plasma volumes did not differ between the groups., Conclusion: This study does not support the hypothesis that the plasma-volume-expanding effect of albumin relative to that of crystalloids is decreased under conditions characterized by increased permeability.

Intravenous fluid therapy and perception of volume effects are often misunderstood. The pharmacokinetical difference between colloids and crystalloids depends on the condition of the vascular permeability barrier. Its functioning is still largely based on Starling's principle from 1896, realising that transport of fluid to and from the interstitial space follows the balance between opposing oncotic and hydrostatic pressures. In the past decade, the endothelial glycocalyx, located on the luminal side of healthy vasculature, has increasingly been taken into consideration around models of transvascular fluid filtration. While crystalloids can freely pass through the glycocalyx, colloids are held back in the vasculature by this structure. This is reflected by a markedly higher intravascular persistence of isooncotic colloids (80-100%) versus crystalloids (around 20%), at least as long as the glycocalyx is intact. Protecting this structure in surgical practice means limiting the surgical trauma and avoiding intravascular hypervolemia., (Copyright © 2014. Published by Elsevier Ltd.)

Background: The infusion of crystalloid solutions is a fundamental part of the management of critically ill patients. These solutions are used to maintain the balance of water and essential electrolytes and replace losses when patients have limited gastrointestinal intake. They also act as carriers for intravenous infusion of medication and red cells. The most commonly used solution, 0.9% saline, has equal concentrations of Na(+) and Cl(-) even though the plasma concentration of Na(+) normally is 40 meq/L higher than that of Cl(-). The use of this fluid thus can produce a hyperchloremic acidosis in a dose-dependent manner, but it is not known whether this has clinical significance., Approach: The first part of this article deals with the significance of Na(+) and Cl(-) in normal physiology. This begins with examination of their roles in the regulation of osmolality, acid-base balance, and generation of electrochemical gradients and why the concentration of Cl(-) normally is considerably lower than that of Na(+). The next part deals with how their concentrations are regulated by the gastrointestinal tract and kidney. Based on the physiology, it would seem that solutions in which the concentration of Na(+) is "balanced" by a substance other than Cl(-) would be advantageous. The final part examines the evidence to support that point., Conclusions: There are strong observational data that support the notion that avoiding an elevated Cl(-) concentration or using fluids that reduce the rise in Cl(-) reduces renal dysfunction, infections, and possibly even mortality. However, observational studies only can indicate an association and cannot indicate causality. Unfortunately, randomized trials to date are far too limited to address this crucial issue. What is clear is that appropriate randomized trials will require very large populations. It also is not known whether the important variable is the concentration of Cl(-), the difference in concentrations of Na(+) and Cl(-), or the total body mass of Cl(-)., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Microdialysis sampling is a commonly used technique for collecting solutes from the extracellular space of tissues in laboratory animals and humans. Large molecular weight solutes can be collected using high molecular weight cutoff (MWCO) membranes (100kDa or greater). High MWCO membranes require addition of high molecular weight dextrans or albumin to the perfusion fluid to prevent fluid loss via ultrafiltration. While these perfusion fluid additives are commonly used during microdialysis sampling, the tissue response to the loss of these compounds across the membrane is poorly understood. Tissue reactions to implanted microdialysis sampling probes containing different microdialysis perfusion fluids were compared over a 7-day time period in rats. The base perfusion fluid was Ringer's solution supplemented with either bovine serum albumin (BSA), rat serum albumin (RSA), Dextran-70, or Dextran-500. A significant inflammatory response to Dextran-70 was observed. No differences in the tissue response between BSA and RSA were observed. Among these agents, the BSA, RSA, and Dextran-500 produced a significantly reduced inflammatory response compared to the Dextran-70. This work demonstrates that use of Dextran-70 in microdialysis sampling perfusion fluids should be eliminated and replaced with Dextran-500 or other alternatives., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Juvenile pigs are prone to hypoglycemia, nevertheless they are commonly used in preclinical studies. The optimal perioperative fluid management with crystalloid solutions in such settings has not yet been studied. The aim of the current study was to correlate the perioperative fluid administration of Ringer's solution, with and without the addition of a minimal amount of glucose (0.4% glucose) to the blood glucose, and the incidence of perioperative hypoglycemia in 20 juvenile pigs (31.7 ± 5.2 kg) undergoing surgery for approximately one hour. Infusion of Ringer's solution without glucose (group Ri, n = 10) led to a significant decrease of the serum blood glucose level from 105.7 ± 27.1 mg/dL at baseline compared with 87.8 ± 31.7 mg/dL post surgery. The pigs (50%) in group Ri were observed to be hypoglycemic (<72 mg/dL). The second group received Ringer's solution containing a final concentration of 0.4% glucose (group Ri-Glu, n = 10) and showed a significant increase in blood glucose level from 104.4 ± 15.8 mg/dL at baseline compared with 122.3 ± 14.3 mg/dL post surgery. No animal in group Ri-Glu was observed to be hypoglycemic. In conclusion, we showed that even minor changes in perioperative crystalloid fluid management significantly influence blood glucose levels. In order to avoid hypoglycemia in juvenile pigs we recommend adding a minimal amount of glucose (0.4% final concentration) to the Ringer's solution given perioperatively during surgery of approximately one hour.

Removal of plasma proteins from perfusates increases vascular permeability. The common interpretation of the action of albumin is that it forms part of the permeability barrier by electrostatic binding to the endothelial glycocalyx. We tested the alternate hypothesis that removal of perfusate albumin in rat venular microvessels decreased the availability of sphingosine-1-phosphate (S1P), which is normally carried in plasma bound to albumin and lipoproteins and is required to maintain stable baseline endothelial barriers (Am J Physiol Heart Circ Physiol 303: H825-H834, 2012). Red blood cells (RBCs) are a primary source of S1P in the normal circulation. We compared apparent albumin permeability coefficients [solute permeability (Ps)] measured using perfusates containing albumin (10 mg/ml, control) and conditioned by 20-min exposure to rat RBCs with Ps when test perfusates were in RBC-conditioned protein-free Ringer solution. The control perfusate S1P concentration (439 ± 46 nM) was near the normal plasma value at 37 °C and established a stable baseline Ps (0.9 ± 0.4 × 10(-6) cm/s). Ringer solution perfusate contained 52 ± 8 nM S1P and increased Ps more than 10-fold (16.1 ± 3.9 × 10(-6) cm/s). Consistent with albumin-dependent transport of S1P from RBCs, S1P concentrations in RBC-conditioned solutions decreased as albumin concentration, hematocrit, and temperature decreased. Protein-free Ringer solution perfusates that used liposomes instead of RBCs as flow markers failed to maintain normal permeability, reproducing the "albumin effect" in these mammalian microvessels. We conclude that the albumin effect depends on the action of albumin to facilitate the release and transport of S1P from RBCs that normally provide a significant amount of S1P to the endothelium.

Introduction: The turnover of Ringer´s solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia. The present study evaluates whether the kinetics is affected by previous infusion of colloid fluid., Methods: Ten male volunteers with a mean age of 22 years underwent three infusion experiments, on separate days and in random order. The experiments included 10 mL/kg of 6% hydroxyethyl starch 130/0.4 (Voluven™), 20 mL/kg of Ringer's acetate, and a combination of both, where Ringer´s was administered 75 minutes after the starch infusion ended. The kinetics of the volume expansion was analysed by non-linear least- squares regression, based on urinary excretion and serial measurement of blood haemoglobin concentration for up to 420 minutes., Results: The mean volume of distribution of the starch was 3.12 L which agreed well with the plasma volume (3.14 L) estimated by anthropometry. The volume expansion following the infusion of starch showed monoexponential elimination kinetics with a half-life of two hours. Two interaction effects were found when Ringer´s acetate was infused after the starch. First, there was a higher tendency for Ringer´s acetate to distribute to a peripheral compartment at the expense of the plasma volume expansion. The translocated amount of Ringer´s was 70% higher when HES had been infused earlier. Second, the elimination half-life of Ringer´s acetate was five times longer when administered after the starch (88 versus 497 minutes, P<0.02)., Conclusions: Starch promoted peripheral accumulation of the later infused Ringer´s acetate solution and markedly prolonged the elimination half-life., Trial Registration: ClinicalTrials.gov: NCT01195025.

There is increasing evidence that intraoperative fluid therapy decisions may influence postoperative outcomes. In the past, patients undergoing major surgery were often administered large volumes of crystalloid, based on a presumption of preoperative dehydration and nebulous intraoperative 'third space' fluid loss. However, positive perioperative fluid balance, with postoperative fluid-based weight gain, is associated with increased major morbidity. The concept of 'third space' fluid loss has been emphatically refuted, and preoperative dehydration has been almost eliminated by reduced fasting times and use of oral fluids up to 2 h before operation. A 'restrictive' intraoperative fluid regimen, avoiding hypovolaemia but limiting infusion to the minimum necessary, initially reduced major complications after complex surgery, but inconsistencies in defining restrictive vs liberal fluid regimens, the type of fluid infused, and in definitions of adverse outcomes have produced conflicting results in clinical trials. The advent of individualized goal-directed fluid therapy, facilitated by minimally invasive, flow-based cardiovascular monitoring, for example, oesophageal Doppler monitoring, has improved outcomes in colorectal surgery in particular, and this monitor has been approved by clinical guidance authorities. In the contrasting clinical context of relatively low-risk patients undergoing ambulatory surgery, high-volume crystalloid infusion (20-30 ml kg(-1)) reduces postoperative nausea and vomiting, dizziness, and pain. This review revises relevant physiology of body water distribution and capillary-tissue flow dynamics, outlines the rationale behind the fluid regimens mentioned above, and summarizes the current clinical evidence base for them, particularly the increasing use of individualized goal-directed fluid therapy facilitated by oesophageal Doppler monitoring.

It is well known that ultrasound enhances drug delivery to tissues, although there is not a general consensus about the responsible mechanisms. However, it is known that the most important factor associated with ultrasonically-enhanced drug permeance through tissues is cavitation. Here we report results from research conducted using a experimental approach adapted from single bubble sonoluminescence experiments which generates very well defined acoustic fields and allows controlled activation and location of cavitation. The experimental design requires that a biological tissue be immersed inside a highly degassed liquid media to avoid random bubble nucleation. Therefore, live frog bladders were used as the living tissue due to their high resistance to hypoxia. Tissue membrane permeance was measured using radiolabeled urea. The results show that an increase in tissue permeance only occurs when cavitation is present near the tissue membrane. Moreover, confocal microscopy shows a direct correlation between permeance increases and physical damage to the tissue.

Purpose: To determine whether palmitic acid methyl ester (PAME) or methyl palmitate is the retina-derived relaxing factor (RRF)., Methods: A superfusion bioassay cascade technique was used with rat isolated retina as donor tissue and rat aortic ring as detector tissue. The superfusate was analyzed with gas chromatography/mass spectrometry (GC/MS). The biochemical and pharmacologic characteristics of RRF and PAME were compared., Results: The authors demonstrated that the retina on superfusion with Krebs solution spontaneously released RRF (indicated by aortic ring relaxation) and PAME (measured by GC/MS). The release of RRF and PAME was calcium dependent because the release was abolished when the retinas were superfused with calcium-free Krebs solution. Furthermore, aortic relaxations induced by RRF and PAME were not affected after heating their solutions at 70 degrees C for 1 hour, suggesting that both are heat stable. Exogenous PAME concentration dependently induced aortic relaxation with EC50 of 0.82+/-0.75 pM. The aortic relaxations induced by RRF and exogenous PAME were inhibited by 4-aminopyridine (2 mM) and tetraethylammonium (TEA, 10 mM) but were not affected by TEA at 1 mM or 3 mM, glibenclamide (3 microM), or iberiotoxin (100 nM). The vasodilator activity of Krebs solution containing RRF or exogenous PAME was greatly attenuated after hexane extraction., Conclusions: RRF and PAME share similar biochemical properties and react similarly to all pharmacologic inhibitors examined. Both act primarily on the voltage-dependent K+ (Kv) channel of aortic smooth muscle cells, causing aortic relaxation. These results suggest that PAME is the hydrophobic RRF.

Purpose: To evaluate the effects of fluid administration on microcirculatory alterations in sepsis., Methods: With a Sidestream Dark Field device, we evaluated the effects of fluids on the sublingual microcirculation in 60 patients with severe sepsis. These patients were investigated either within 24 h (early, n = 37) or more than 48 h (late, n = 23) after a diagnosis of severe sepsis. Hemodynamic and microcirculatory measurements were obtained before and 30 min after administration of 1,000 ml Ringer's lactate (n = 29) or 400 ml 4% albumin (n = 31) solutions., Results: Fluid administration increased perfused small vessel density from 3.5 (2.9-4.3) to 4.4 (3.7-4.9) n/mm (p < 0.01), through a combined increase in the proportion of perfused small vessels from 69 (62-76) to 79 (71-83) %, p < 0.01) and in small vessel density from 5.3 (4.4-5.9) to 5.6 (4.8-6.3) n/mm (p < 0.01). Importantly, microvascular perfusion increased in the early but not in the late phase of sepsis: the proportion of perfused small vessels increased from 65 (60-72) to 80 (75-84) % (p < 0.01) in the early phase and from 75 (66-80) to 74 (67-81) (p = ns) in the late phase. These microvascular effects of fluids were not related to changes in cardiac index (R(2) = 0.05, p = ns) or mean arterial pressure (R(2) = 0.04, p = ns)., Conclusions: In this non-randomized trial, fluid administration improved microvascular perfusion in the early but not late phase of sepsis. This effect is independent of global hemodynamic effects and of the type of solution.

Veins have historically been discussed in qualitative, relative terms: "more compliant" than arteries, subject to "lower pressures". The structural and compositional differences between arteries and veins are directly related to the different functions of these vessels. Veins are often used as grafts to reroute flow from atherosclerotic arteries, and venous elasticity plays a role in the development of conditions such as varicose veins and valvular insufficiency. It is therefore of clinical interest to determine the elastomechanical properties of veins. In the current study, both tensile and vibration testing are used to obtain elastic moduli of bovine veins. Representative stress-strain data are shown, and the mechanical and failure properties reported. Nonlinear and viscoelastic behavior is observed, though most properties show little strain rate dependence. These data suggest parameters for constitutive modeling of veins and may inform the design and testing of prosthetic venous valves as well as vein grafts., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Background: Historically, a reduced serum sodium concentration has been used to diagnose absorption of electrolyte-free irrigating fluid during transurethral resection of the prostate (TURP). In bipolar TURP, the irrigating solution contains electrolytes, thus invalidating the serum sodium method. In this study, we investigated whether glucose can be used to diagnose the absorption of irrigating fluid during TURP procedures., Methods: The serum glucose and sodium concentrations were measured in 250 patients undergoing monopolar TURP using either 1.5% glycine or 5% glucose for urinary bladder irrigation. The glucose kinetics was analyzed in 10 volunteers receiving a 30-min infusion of 20 mL/kg of acetated Ringer's solution with 1% glucose. These data were then used in computer simulations of different absorption patterns that were summarized in a nomogram for the relationship between the glucose level and administered fluid volume., Results: There was a statistically significant inverse linear relationship between the decrease in serum sodium and the increase in glucose levels after absorption of 5% glucose during TURP (r(2) = 0.80). The glucose concentration increased, from 4.6 (sd 0.4) to 8.3 (0.9) mmol/L, during the experimental infusions. Regardless of the absorption pattern, all simulations indicated that the uptake of 1 L of fluid containing 1% glucose corresponded to an increase in the glucose level of 3.7 (sd 1.6) mmol/L at the end of surgery, whereas 2 L yielded an increase of 6.9 (1.7) mmol/L., Conclusions: In bipolar TURP, the addition of glucose to a concentration of 1% in the electrolyte-containing irrigation fluid can be used as a tracer of absorption that is comparable with measuring serum sodium after monopolar TURP.

Purpose: To measure closing pressure in a series of new Model FP7 silicone Ahmed Glaucoma Valves (AGVs), using an in vitro gravity-driven system, in which closing pressure was measured directly from a dual manometer/pressure reservoir., Method: A straight length of tubing served as an open manometer, which connected via a 3-way stopcock to the inlet of the AGV submerged under 1.5 cm of balanced saline solution (BSS). Six AGV were assessed in 5 sequential trials and the mean inlet pressure at 90 minutes was recorded as the closing pressure. After testing, a single valve was primed a second time using greater force and retested. Control trials were performed with a submerged 26-G cannula opening directly into the BSS bath., Results: At 90 minutes, the 6 valves equilibrated at a mean inlet pressure of 7.1 mm Hg, with a range from 1.4 to 13.5 mm Hg. Closing pressures at or less than 5 mm Hg were measured in half (3/6) of the valves tested. The average flow of BSS across the valves in the final 30 minutes was less than 1.5x10(-2) microL/min. In the single valve reperfused under greater pressure, the closing pressure increased., Conclusions: Model FP7 AGVs, in vitro, exhibit significant variability in closing pressure, with half closing at intraocular pressures considered potentially problematic in clinical situations. The results of the high-pressure perfusion experiment suggest that more research into the priming process is required so a precise description can be developed for surgeons.

The achievement of euvolemia is essential to the successful management of peritoneal dialysis patients. However, the concern that hypertonic glucose exchanges may have a role in long-term changes to the peritoneal membrane has lead to an alternative strategy to enhance ultrafiltration (UF) over the long dwell by combining crystalloid and colloid osmosis. This review summarizes the experience of mixing glucose or amino acids with polyglucose (icodextrin), with particular focus given to data from studies using glucose/icodextrin in combinations of 1.36%/7.5% and 2.61%/6.8%. Both combinations demonstrate a significant increment of UF volume and sodium removal compared with the component osmotic agents used individually over long dwells, with the 2.61%/6.8% mixture having an effect over dwells extending to 15 h. Hypothetically, the mechanism of the enhanced UF is the attenuation by the colloid osmotic force of the backflow of water through small pores from dialysate to the peritoneal capillary circulation once the crystalloid osmotic force has dissipated. This experience provides promising data that deserves further examination in longer term clinical studies.

ICln is a ubiquitous, multifunctional protein with functions in cell volume regulation and RNA processing, and is thus part of an intricate protein network critically involved in the homoeostasis of cells. To better understand this vital protein network in health and disease it is fundamental to characterize the interactions between the physiological pathways in which ICln is involved, as well as the spatio-temporal regulation of these interactions. In this study, we focused on the interaction between the two best studied pathways in which ICln is involved--regulatory volume decrease and RNA processing--and asked, whether or not the RNA processing factor and ICln interaction partner LSm4 may also have a function in cell volume regulation in NIH3T3 fibroblasts or HEK293 Phoenix cells. To address this question, we studied in isotonic and hypotonic conditions by FRET, biochemistry and electrophysiology, the intracellular distribution of the RNA processing factor LSm4, its interaction with ICln, as well as the involvement of LSm4 in the activation of the swelling dependent anion and osmolyte channel IClswell. In isotonic conditions, LSm4 associates with ICln, and the plasma membrane. Hypotonic cell swelling leads to the dissociation of LSm4 from the plasma membrane, and from ICln. Over-expression of LSm4 affects the translocation of ICln to the cell membrane and markedly inhibits the activation kinetics and current density of IClswell. These findings indicate that LSm4 not only acts in RNA processing, but also as a co-factor in cell volume regulation., (Copyright 2008 S. Karger AG, Basel.)

The outer hair cell (OHC) is a hydrostat with a low hydraulic conductivity of Pf=3x10(-4) cm/s across the plasma membrane (PM) and subsurface cisterna that make up the OHC's lateral wall. The SSC is structurally and functionally a transport barrier in normal cells that is known to be disrupted by salicylate. The effect of sodium salicylate on Pf is determined from osmotic experiments in which isolated, control and salicylate-treated OHCs were exposed to hypotonic solutions in a constant flow chamber. The value of Pf=3.5+/-0.5x10(-4) cm/s (mean+/-s.e.m., n=34) for salicylate-treated OHCs was not significantly different from Pf=2.4+/-0.3x10(-4) cm/s (mean+/-s.e.m., n=31) for untreated OHCs (p=.3302). Thus Pf is determined by the PM and is unaffected by salicylate treatment. The ratio of longitudinal strain to radial strain epsilonz/epsilonc=-0.76 for salicylate-treated OHCs was significantly smaller (p=.0143) from -0.72 for untreated OHCs, and is also independent of the magnitude of the applied osmotic challenge. Salicylate-treated OHCs took longer to attain a steady-state volume which is larger than that for untreated OHCs and increased in volume by 8-15% prior to hypotonic perfusion unlike sodium alpha-ketoglutarate-treated OHCs. It is suggested that depolymerization of cytoskeletal proteins and/or glycogen may be responsible for the large volume increase in salicylate-treated OHCs as well as the different responses to different modes of application of the hypotonic solution.

Background: Rapid crystalloid infusion enhances coagulation, regardless of electrolytes, pH or osmolality, an effect thought to be related to deep vein thrombosis and other clot formations. Altered serum magnesium may play a role in the balance of coagulation. In this in vivo study we investigated the coagulation response to rapid hemodilution when serum magnesium is maintained or partially increased., Methods: Twenty-five healthy volunteers were investigated on three occasions, randomly receiving normal saline, Balsol (magnesium 1.5 g/L), and Balsol plus additional magnesium (magnesium 3.0 g/L). Investigators were blinded to the solution's identity. Baseline blood samples were taken measuring hematocrit, serum magnesium, and thrombelastography (TEG), whereafter 14 mL/kg (20% blood volume) was infused over 30 min, followed by a second blood sample. All results were compared to their own baseline values using ANOVA with LSD post hoc significance testing., Results: All groups had a similar postdilutional hematocrit decrease, with significant magnesium reduction in the saline group (0.81 +/- 0.07 to 0.74 +/- 0.07 (approximately -8.6%) (P < 0.003)), no change in the Balsol group and significant increase in the Balsol + magnesium group (0.84 +/- 0.07 to 0.99 +/- 0.06 (approximately 17.9%) (P < 0.001)). Postdilutional TEG results reflected no significant change from control in the Balsol + magnesium group. Both of the other two groups had statistically significant increased clot formation (reaction time to onset of clotting and clotting time shortened; alpha-angle increased)., Conclusions: Rapid hemodilution-induced coagulation may be partially due to decreased magnesium, and the effect is attenuated by maintaining magnesium at the upper limit of normal. Crystalloid resuscitation fluids should possibly contain higher magnesium levels, around 3 mmol/L.

Moderate hemolytic anemia, abnormal erythrocyte morphology (spherocytosis), and decreased membrane stability are observed in mice with complete deficiency of all erythroid protein 4.1 protein isoforms (4.1(-/-); Shi TS et al. J Clin Invest 103: 331, 1999). We have examined the effects of erythroid protein 4.1 (4.1R) deficiency on erythrocyte cation transport and volume regulation. 4.1(-/-) mice exhibited erythrocyte dehydration that was associated with reduced cellular K and increased Na content. Increased Na permeability was observed in these mice, mostly mediated by Na/H exchange with normal Na-K pump and Na-K-2Cl cotransport activities. The Na/H exchange of 4.1(-/-) erythrocytes was markedly activated by exposure to hypertonic conditions (18.2 +/- 3.2 in 4.1(-/-) vs. 9.8 +/- 1.3 mmol/10(13) cell x h in control mice), with an abnormal dependence on osmolality (EC(50) = 417 +/- 42 in 4.1(-/-) vs. 460 +/- 35 mosmol/kgH(2)O in control mice), suggestive of an upregulated functional state. While the affinity for internal protons was not altered (K(0.5) = 489.7 +/- 0.7 vs. 537.0 +/- 0.56 nM in control mice), the V(max) of the H-induced Na/H exchange activity was markedly elevated in 4.1(-/-) erythrocytes (V(max) 91.47 +/- 7.2 compared with 46.52 +/- 5.4 mmol/10(13) cell x h in control mice). Na/H exchange activation by okadaic acid was absent in 4.1(-/-) erythrocytes. Altogether, these results suggest that erythroid protein 4.1 plays a major role in volume regulation and physiologically downregulates Na/H exchange in mouse erythrocytes. Upregulation of the Na/H exchange is an important contributor to the elevated cell Na content of 4.1(-/-) erythrocytes.

Osmotically driven water flow, u (cm/s), between two solutions of identical osmolarity, c(o) (300 mM: in mammals), has a theoretical isotonic maximum given by u = j/c(o), where j (moles/cm(2)/s) is the rate of salt transport. In many experimental studies, transport was found to be indistinguishable from isotonic. The purpose of this work is to investigate the conditions for u to approach isotonic. A necessary condition is that the membrane salt/water permeability ratio, epsilon, must be small: typical physiological values are epsilon = 10(-3) to 10(-5), so epsilon is generally small but this is not sufficient to guarantee near-isotonic transport. If we consider the simplest model of two series membranes, which secrete a tear or drop of sweat (i.e., there are no externally-imposed boundary conditions on the secretion), diffusion is negligible and the predicted osmolarities are: basal = c(o), intracellular approximately (1 + epsilon)c(o), secretion approximately (1 + 2epsilon)c(o), and u approximately (1 - 2epsilon)j/c(o). Note that this model is also appropriate when the transported solution is experimentally collected. Thus, in the absence of external boundary conditions, transport is experimentally indistinguishable from isotonic. However, if external boundary conditions set salt concentrations to c(o) on both sides of the epithelium, then fluid transport depends on distributed osmotic gradients in lateral spaces. If lateral spaces are too short and wide, diffusion dominates convection, reduces osmotic gradients and fluid flow is significantly less than isotonic. Moreover, because apical and basolateral membrane water fluxes are linked by the intracellular osmolarity, water flow is maximum when the total water permeability of basolateral membranes equals that of apical membranes. In the context of the renal proximal tubule, data suggest it is transporting at near optimal conditions. Nevertheless, typical physiological values suggest the newly filtered fluid is reabsorbed at a rate u approximately 0.86 j/c(o), so a hypertonic solution is being reabsorbed. The osmolarity of the filtrate c(F) (M) will therefore diminish with distance from the site of filtration (the glomerulus) until the solution being transported is isotonic with the filtrate, u = j/c(F).With this steady-state condition, the distributed model becomes approximately equivalent to two membranes in series. The osmolarities are now: c(F) approximately (1 - 2epsilon)j/c(o), intracellular approximately (1 - epsilon)c(o), lateral spaces approximately c(o), and u approximately (1 + 2epsilon)j/c(o). The change in c(F) is predicted to occur with a length constant of about 0.3 cm. Thus, membrane transport tends to adjust transmembrane osmotic gradients toward epsilonc(o), which induces water flow that is isotonic to within order epsilon. These findings provide a plausible hypothesis on how the proximal tubule or other epithelia appear to transport an isotonic solution.

The exhaled breath condensate (EBC) method represents a new, noninvasive way to detect inflammatory and metabolic markers in the fluid that covers the airways [epithelial lining fluid (ELF)]. However, respiratory droplets represent only a very small and variable fraction of the EBC, most (approximately 99.99%) of which is water vapor. Our objective was to show that ELF concentrations could be calculated from EBC values by using any of three dilutional indicators (urea, total cations, and conductivity) in nine normal and nine chronic obstructive lung disease (COPD) subjects. EBC concentrations of Na(+), K(+), Ca(2+), Mg(2+), total cations, urea, and conductivity varied over a 10-fold range among individuals, but concentrations of these constituents (except Ca(2+)) remained well correlated (r(2) = 0.44-0.83, P < 0.001). Dilution (D) of respiratory droplets in water vapor was calculated by dividing plasma concentrations of the dilutional indicators by EBC concentrations. Estimates of D were not significantly different among these indicators, and urea D averaged 10,800 +/- 2,100 (SE) in normal and 12,600 +/- 3,300 in COPD subjects. Although calculated Na(+) concentrations in the ELF were less than one-half those in plasma, and concentrations of K(+), Ca(2+), and Mg(2+) exceeded those in plasma, total cation concentrations in ELF were not significantly different from those in plasma, indicating that ELF is isotonic in both normal and COPD subjects. EBC amylase concentrations (measured with an ultrasensitive procedure) indicated that saliva represented <10% of the respiratory (ELF) droplets in all but three samples. Dilutional and salivary markers are essential for interpretation of EBC studies.

Isotonic NaCl is ingested in addition to water by cell-dehydrated rats in two-bottle tests. The objective of the present work was to find out whether mineral intake in the cell-dehydrated rat is specific to NaCl in a five-bottle test. Adult male Sprague Dawley rats had distilled water and four mineral solutions at palatable concentrations (0.01 M KCl, 0.05 mM CaCl2, 0.15 M NaHCO3, 0.15 M NaCl) simultaneously available for consumption. Cell-dehydration was produced infusing 1.5 ml of NaCl solution (0.15, 0.25, 0.5, 1.0, 2.0, 4.0 M) intravenously for 10 min and intakes were recorded for the next hour. It was observed a NaCl concentration-dependent increase in 0.01 M KCl intake. The ingestion of the other mineral solutions was not significantly altered compared to infusion of 0.15 M NaCl. The ingestion of KCl was not related to changes in serum potassium concentration. The ingestion of KCl was reduced in half and water was the preferred fluid when the five-bottle test was performed with mineral solutions at isomolar (0.15 M) concentrations. There was no increase in intake of other mineral solution in the isomolar test. No preference was observed for palatable or isomolar solutions during early extracellular dehydration until 4 h after subcutaneous injection of furosemide, in spite of the increase in total volume intake. Therefore, mineral intake induced by cell dehydration is not specific for NaCl solution. The type of mineral solution available influences the choice and KCl is the preferred solution of the cell-dehydrated rat in the conditions of the present study.

The substrate composition containing succinic acid, substrates for succinate synthesis, and antioxidants increased the efficiency of pharmacotherapy in patients with coronary heart disease and hypertension. We revealed an increase in the quality of life and decrease in the functional class of heart failure, incidence of arrhythmias and exercise-related pain, and blood cholesterol concentration.

Purpose: To quantify spontaneous fluid transport across the isolated ciliary bodies of rabbit and bovine and to determine their osmotic permeabilities., Methods: A complete annulus of ciliary body was mounted in a custom-designed chamber appropriate for detecting net fluid movement across the in vitro preparation., Results: A net fluid flow in the blood-to-aqueous direction was measured. It was generally observed that tissue freshness is a critical parameter for detection of such flow. The spontaneous, baseline fluid transport rate lasted, on average, approximately 4 hours. This flow solely reflects the secretory activity of the isolated ciliary epithelium, since the in vitro arrangement precludes contributions from ultrafiltration. Both the isolated rabbit and bovine ciliary body epithelia transported fluid in the absence of an external osmotic or pressure gradient. After corrections for area and possible collapse of the processes, a total flux rate of approximately 23 microL/hour or 13% of the in vivo flow in rabbit was estimated. This value agrees with predictions of ionic fluxes and short-circuit current measurements, which are also obtained in vitro. The fluid flow is bicarbonate dependent in rabbit and chloride dependent in bovine, consistent with ionic transport mechanisms described in these species. Ouabain inhibited the fluid flow across both species, indicating dependence on active ionic transport. Irrespective of the spontaneous fluid transport, a flow elicited by an osmotic gradient allowed for a calculation of the osmotic permeability coefficient (P(f); approximately 10(-3) cm/s) in line with reports in other epithelia. In addition, mannitol permeability (5.6 x 10(-6) cm/sec) was similar to that measured in "tight" epithelia, as determined by measurements of radiolabeled fluxes of the sugar across rabbit ciliary bodies mounted in the chambers used for the present fluid transport study., Conclusions: This work demonstrates that isolated ciliary epithelial preparations transport fluid in the blood-to-aqueous direction. The present observations suggest that mounting arrangements for measuring volumetric fluid flow across the ciliary epithelium is suitable for future studies directed toward the pharmacological control of secretion.

Unlabelled: Resuscitation with racemic lactated Ringer's solution (containing equal amounts of D and L isomers of lactate) has been shown to induce pulmonary apoptosis. Substitution of DL-isomer lactate with ketone bodies (beta-hydroxybutyrate, BHB), sodium pyruvate, or L-isomer of lactate decrease this injury without changing the energy status of the tissues or the expression of apoptotic genes. These modified solutions however alter the function of apoptotic proteins through an unknown mechanism. We postulated that DL-LR induces apoptosis by restricting the phosphorylation of key apoptotic proteins., Methods: Male Sprague Dawley rats (n = 30, 5/group) were subjected to a three stage, volume-controlled hemorrhage and randomized to the following groups. 1) No hemorrhage (Sham); 2) Hemorrhage and no resuscitation (NR); 3) Resuscitation with 3x shed blood volume of racemic LR (DL-LR); 4) Resuscitation with 3x shed blood volume of LR containing only the L-isomer of lactate (L-LR); 5) Resuscitation with 3s shed blood volume of pyruvate Ringer's (PR); 6) Resuscitation with 3s shed blood volume of ketone Ringer's (KR). The modified Ringer's solutions were identical to racemic LR except for equimolar substitution of DL-lactate for L-lactate, pyruvate and BHB respectively. Lung tissue was obtained 2 hours later and subjected to Western Blotting. The levels of Akt, Bad, and eNOS (total and phosphorylated) proteins were measured. Finally, the expression of gene coding for protein 14-3-3 was measured using RT-PCR., Results: Resuscitation with DL-LR caused a significant (p < 0.05) increase in the total Bad and a decrease in phosphorylated Bad protein expression in the lung. It also caused an increase in the phosphorylated Akt levels and a decrease in gene coding for protein 14-3-3. These changes were consistent with signaling imbalances that favor apoptosis. Modified LR solutions, on the other hand, did not cause these alterations. Phosphorylation pattern of eNOS supported the involvement of PI3K/Akt pathway in this process., Conclusion: Racemic lactate plays a role in the induction of pulmonary apoptosis by restricting phosphorylation of Bad and eNOS proteins.

Unlabelled: Acetated Ringer's solution is a slightly hypotonic infusion fluid (osmolality 270 mosmol/kg) that has inspired the belief that the fluid causes a shift of water volume to the intracellular space. We assessed the role of the kidney in modifying this volume shift by infusing 25 mL/kg of Ringer's acetate solution (mean, 1565 mL) over a time period of 15, 30, 45, and 80 min on different occasions in 5 healthy female volunteers. Regardless of the rate of administration, the excreted urine contained only half as much sodium (mean, 67 mmol/L) as the infused fluid. As there was only a slight increase of 0.9 mmol/L in the serum sodium level, mass balance calculations indicated that 274 mL of water had shifted from the intracellular to the extracellular space 30 min after the infusions ended (P < 0.001). This fluid shift was also maintained over the subsequent 90 min. In conclusion, infusion of Ringer's acetate solution does not promote cellular swelling as a result of the excretion of urine that is low in sodium. A slight dehydration of fluid from the intracellular space still persisted when our measurements ended 2 h after completing the infusion., Implications: The kidney promotes slight cellular dehydration after infusion of Ringer's acetate solution by rapid excretion of water, whereas natriuresis occurs more slowly. In volunteers, this translocation amounted to 18% of the infused fluid volume and persisted for at least 2 h.

Cellular element concentrations and dry weight contents in A6 cells were determined using electron microprobe analysis to establish whether these cells exhibit a regulatory volume increase (post-RVD-RVI) when re-establishing isotonicity following a hypotonically induced regulatory volume decrease (RVD). Hypotonic stress was induced by reducing basolateral [NaCl], and hence, osmolarity fell from 260 to 140 mosmol/l. The alterations in cell volume after re-establishing isotonicity, calculated from the cellular dry weight changes, indicate within the first 2 min cell shrinkage from 120 to 76% of control, compatible with almost ideal osmometric behaviour of A6 cells, and thereafter a post-RVD-RVI to 94%. The cellular uptake of osmolytes necessary to explain the post-RVD-RVI could be accounted for solely by a gain in cellular K and Cl. The involvement of a Na-K-2Cl cotransporter in most of the KCl uptake seems plausible since basolateral bumetanide blocked KCl uptake and post-RVD-RVI. The net uptake of cations (K uptake of 185.2, Na loss of 8.2 mmol/kg dry wt) during the isotonic period exceeded the Cl uptake by 38.2 mmol/kg dry wt, suggesting the uptake of another anion and/or the alteration of cellular buffer capacity. The relatively low Na concentration maintained during the isotonic period (13.3 vs. 20.4 mmol/kg wet wt under control conditions) might favour electrolyte uptake via the Na-K-2Cl cotransporter.

Hypertonic saline, Dextran, and albumin have been advocated for rapid restoration of intravascular volume. The goal of this study was to define how albumin impacts the effects of hypertonic saline and Dextran on hydraulic permeability. We hypothesized that albumin would decrease the hydraulic permeability (L(p)) of isotonic and hypertonic solutions containing Dextran. Using the modified Landis micro-occlusion technique, single rat mesenteric venules were perfused with either Ringer's + 1% albumin (RA) or hypertonic saline + 1% albumin (HSA). In sequential cannulations of the venules, 1%, 2%, and 3% Dextran was added to the RA perfusion (n = 6) and the HSA perfusion (n = 6). These results were compared with similar studies completed without albumin. Albumin significantly decreased L(p) with all HS solutions studied compared with HS without albumin. Baseline L(p) measurements for RA and HSA solutions were 1.08 +/- 0.07 and 0.51 +/- 0.03, respectively. In the RA group, 2% and 3% Dextran was associated with a lower L(p) of 0.83 +/- 0.04 (P = 0.002) and 0.67 +/- 0.05 (P = 0.002), respectively. In the HSA group, 2% and 3% Dextran was associated with a lower L(p) of 0.37 +/- 0.02 (P = 0.001) and 0.32 +/- 0.02 (P < 0.0001), respectively. All values for L(p) are x 10(-7) cm x s(-1) x cmH2O(-1). Albumin maintains low hydraulic permeability levels during perfusion with hypertonic saline. In the setting of sufficient of endothelial albumin levels, hypertonic saline and Dextran may be advantageous when used for resuscitation by decreasing trans-endothelial fluid flux and augmenting intravascular volume.

Background: The intrarenal natriuretic hormone dopamine (DA) is metabolised by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). Inhibition of COMT, as opposed to MAO, results in a potent natriuretic response in the rat. The present study in anaesthetized homozygous and heterozygous COMT gene deleted mice attempted to further elucidate the importance of COMT in renal DA and sodium handling. After acute intravenous isotonic sodium loading, renal function was followed., Results: COMT activity in heterozygous mice was about half of that in wild type mice and was zero in the homozygous mice. MAO activity did not differ between the genotypes. Urinary sodium excretion increased 10-fold after sodium loading in wild type mice. In heterozygous and homozygous mice, the natriuretic effects of sodium loading were only 29 % and 39 %, respectively, of that in wild type mice. Arterial pressure and glomerular filtration rate did not differ between genotypes. Baseline norepinephrine and DA excretions in urine were elevated in the homozygous, but not in heterozygous, COMT gene deleted mice. Urinary DA excretion increased after isotonic sodium loading in the wild type mice but not in the COMT gene deleted mice., Conclusions: Mice with reduced or absent COMT activity have altered metabolism of catecholamines and are unable to increase renal DA activity and produce normal natriuresis in response to acute sodium loading. The results support the hypothesis that COMT has an important role in the DA-mediated regulation of renal sodium excretion.

The main purpose of this theoretical analysis (second of two articles) is to examine whether transjunctional diffusion of NaCl causes intercellular hypertonicity, which permits transcellular water transport across solute-impermeable lateral cell membranes until osmotic equilibration. In the S2 segment with tubular NaCl concentration 140 mM, the calculated apical intercellular NaCl concentration is c0 approximately 132 mM, which exceeds peritubular NaCl concentration by 12 mM or 22 mOsm kg-1. Variations in volume flow, junctional reflection coefficient (sigmaNaCl = 0.25-0.50), gap distance (g = 6-8 A), junctional depth (d = 18-100 A), intercellular diffusion coefficient (DLIS=500-1500 microm2 s-1) and hypothetical active NaCl transport alter c0 only by a fraction of 1 mM. However, dilution and back-leakage of NaHCO3 lower apical intercellular hyperosmolality to approximately 18 mOsm kg-1. Water transport through solute-impermeable lateral cell membranes continues until intercellular and cellular osmolalities are equal. Transcellular and transjunctional volume flow are of similar magnitude (2 nL min-1 mm-1 tubule length) in the S2 segment. Thus, diffusion ensures isotonic absorption of NaCl. Two-thirds of NaHCO3 and other actively transported sodium salts are extruded into the last third of the exponentially widening intercellular space where the exposure time is only 0.9 s. Osmotic equilibration is dependent on aquaporins in the cell membranes. If permeability to water is low, transcellular water transport stops; tubular fluid becomes hypotonic; NaCl diffusion diminishes, but transjunctional water transport remains unaltered as long as transcellular transport of NaHCO3 and other solutes provides the osmotic force.

Purpose: To define the ionic basis for the apical epinephrine-induced increase of fluid absorption (J(V)) across isolated bovine RPE-choroid., Methods: Epinephrine-induced changes in RPE [Ca2+](in) levels were monitored with the ratioing dye fura-2. Transepithelial potential, resistance, and unidirectional fluxes of (36)Cl, (86)Rb (K substitute), and (22)Na were simultaneously determined in paired tissues from the same eye mounted in modified Ussing flux chambers. Radioisotopes (5-7 microCi) were added to the apical bath of one tissue and the basal bath of the other, and the appearance of label in the opposite bath was measured., Results: Apical epinephrine (100 nM) transiently increased [Ca2+](in) by 153 +/- 78 nM. This increase was inhibited by the alpha(1)-adrenoreceptor antagonist prazosin (1 microM) and blocked by CPA(5 microM), an inhibitor of endoplasmic reticulum Ca2+-adenosine triphosphatases (ATPases). Apical epinephrine (100 nM) more than doubled the net Cl absorption rate, increased net K ((86)Rb) absorption by fivefold, and tripled net fluid absorption (J(V)), as predicted by isotonic coupling between ion and fluid transport. The epinephrine-induced increases in ion and fluid transport were completely inhibited by apical bumetanide (100 microM)., Conclusions: Epinephrine increased fluid absorption across bovine RPE by activating apical membrane alpha(1)-adrenergic receptors, increasing [Ca2+](in), and stimulating bumetanide-sensitive Na,K,2Cl uptake at the apical membrane and KCl efflux at the basolateral membrane.

1. In order to study its role in steady state water transport, the Na+-glucose cotransporter (SGLT1) was expressed in Xenopus laevis oocytes; both the human and the rabbit clones were tested. The transport activity was monitored as a clamp current and the flux of water followed optically as the change in oocyte volume. 2. SGLT1 has two modes of water transport. First, it acts as a molecular water pump: for each 2 Na+ and 1 sugar molecule 264 water molecules were cotransported in the human SGLT1 (hSGLT1), 424 for the rabbit SGLT1 (rSGLT1). Second, it acts as a water channel. 3. The cotransport of water was tightly coupled to the sugar-induced clamp current. Instantaneous changes in clamp current induced by changes in clamp voltage were accompanied by instantaneous changes in the rate of water transport. 4. The cotransported solution was predicted to be hypertonic, and an osmotic gradient built up across the oocyte membrane with continued transport; this resulted in an additional osmotic influx of water. After 5-10 min a steady state was achieved in which the total influx was predicted to be isotonic with the intracellular solution. 5. With the given expression levels, the steady state water transport was divided about equally between cotransport, osmosis across the SGLT1 and osmosis across the native oocyte membrane. 6. Coexpression of AQP1 with the SGLT1 increased the water permeability more than 10-fold and steady state isotonic transport was achieved after less than 2 s of sugar activation. One-third of the water was cotransported, and the remainder was osmotically driven through the AQP1. 7. The data suggest that SGLT1 has three roles in isotonic water transport: it cotransports water directly, it supplies a passive pathway for osmotic water transport, and it generates an osmotic driving force that can be employed by other pathways, for example aquaporins.

The fluorescent indicator of nitric oxide (NO), 4,5-diaminofluorescein (DAF-2), and its membrane-permeable derivative (DAF-2 diacetate) have been recently developed to perform real-time biological imaging of NO. In this study, we show that DAF-2 is strongly influenced by factors other than the concentration of NO itself. Using measurements with a fluorimeter as well as fluorescence microscopy, we found that the divalent cation concentration in the medium, as well as the incident light, strongly affects the ability of DAF-2 to detect NO. Calcium, in particular, enhanced the signal detection of NO released by NO donors by up to 200 times. With multiple and longer exposures to light, no bleaching of the dye was observed but, instead, a potentiation of the fluorescence response could be measured. While these two properties will affect the use and interpretation of the hitherto acquired data with this fluorescent compound, they may also open up new possibilities for its application.

A mathematical model of an absorbing leaky epithelium is developed for analysis of solute coupled water transport. The non-charged driving solute diffuses into cells and is pumped from cells into the lateral intercellular space (lis). All membranes contain water channels with the solute passing those of tight junction and interspace basement membrane by convection-diffusion. With solute permeability of paracellular pathway large relative to paracellular water flow, the paracellular flux ratio of the solute (influx/outflux) is small (2-4) in agreement with experiments. The virtual solute concentration of fluid emerging from lis is then significantly larger than the concentration in lis. Thus, in absence of external driving forces the model generates isotonic transport provided a component of the solute flux emerging downstream lis is taken up by cells through the serosal membrane and pumped back into lis, i.e., the solute would have to be recirculated. With input variables from toad intestine (Nedergaard, S., E.H. Larsen, and H.H. Ussing, J. Membr. Biol. 168:241-251), computations predict that 60-80% of the pumped flux stems from serosal bath in agreement with the experimental estimate of the recirculation flux. Robust solutions are obtained with realistic concentrations and pressures of lis, and with the following features. Rate of fluid absorption is governed by the solute permeability of mucosal membrane. Maximum fluid flow is governed by density of pumps on lis-membranes. Energetic efficiency increases with hydraulic conductance of the pathway carrying water from mucosal solution into lis. Uphill water transport is accomplished, but with high hydraulic conductance of cell membranes strength of transport is obscured by water flow through cells. Anomalous solvent drag occurs when back flux of water through cells exceeds inward water flux between cells. Molecules moving along the paracellular pathway are driven by a translateral flow of water, i.e., the model generates pseudo-solvent drag. The associated flux-ratio equation is derived.