Changes In Plasma Electrolytes Research Articles

Changes in plasma electrolytes, minerals, and hepatic markers of health across the transition period in dairy cows divergent in genetic merit for fertility traits and postpartum anovulatory intervals

Peripartum metabolism and subsequent reproductive performance of dairy cows are linked, with maladaptation over the transition period associated with poor reproductive success. A herd of seasonal calving, grazing dairy cows was established that differed in their genetic merit for fertility traits. The heifers were produced by a customized mating program to achieve a 10-percentage point divergence in the New Zealand fertility breeding value (FertBV) as follows: +5 FertBV (POS) versus -5% FertBV (NEG), while also limiting divergence in other breeding values, including body weight, body condition score, and milk production. In this study, we aimed to characterize differences in metabolic, mineral, and metabolic stress marker profiles during their first postpartum transition period as primiparous heifers and to examine if animals with longer postpartum anestrous intervals (PPAI; more than 66 d compared with less than 35 d) had greater metabolic dysfunction. Blood was sampled at -21, -14, -7, 0, 4, 7, 10, 14, 17, 21, 28, and 35 d relative to calving in 455 primiparous cows and plasma analyzed. The NEG cows had lower concentrations of both plasma nonesterified fatty acids and β-hydroxybutyrate at d 7 compared with POS cows. Detailed temporal profiling of various metabolic, mineral, and metabolic stress markers was undertaken in a subset of cows (n = 70). Cows were selected retrospectively to create 4 groups in a 2 × 2 factorial design with either a POS or NEG FertBV and either a short (19-35 d) or long (66-131 d) PPAI. The NEG cows tended, on average, to have lower nonesterified fatty acids and β-hydroxybutyrate concentrations compared with POS cows across the transition period. Mean body weight and body condition score was greatest in NEG cows when compared with the POS cows and an interaction with day demonstrated this only occurred precalving. They also had indications of improved liver health precalving, with higher albumin-to-globulin ratios and lower bilirubin concentrations. Concentrations of aspartate aminotransferase were lower, and the Na-to-Cl ratio was greater in cows with a long versus a short PPAI at d 28 and d 35 after calving, potentially because of cows with a short PPAI (19-35 d) returning to estrous during this time. Magnesium concentrations were lower in NEG cows with a short PPAI from d 21 onwards, indicating NEG cows may metabolically respond to estrous differently than POS cows. The NEG-long PPAI cows had greater gamma-glutamyl transferase concentrations from calving until d 28 and lower bilirubin concentrations throughout the transition period. Together, the results demonstrate significant effects of FertBV on peripartum metabolic status. However, most of the markers tested returned to reference intervals within 4 d after calving or remained within those intervals for the whole transition period, indicating relatively minor biological effects of FertBV on transition period adaptation. The profound differences in reproductive performance among the groups was not explained by underlying differences in metabolic responses during the transition period.

Maintaining Normal Blood Pressure in a Renovascular Stenosis Model of Hypertension in Adult Lewis Rats: Putative Physiological Modulation of the Renin‐Angiotensin System

Prolonged unilateral renal artery stenosis using a Goldblatt Two-Kidney-One Clip (2K1C) technique is a validated scientific approach to inducing experimental hypertension in laboratory animals. This patho-physiological modulation is associated with the activation of the renin-angiotensin system with increased renin and angiotensin II release to initiate hypertension. This mode of experimental hypertension has been demonstrated for many rat strains including Sprague Dawley, Brown Norway and Wistar Kyoto but has not been fully characterized in syngeneic Lewis rats. The objective of this study was to develop and characterize a unilateral renal artery stenosis model of hypertension in adult male Lewis rats using a 2K1C method for hypertension studies in our laboratory. Thirty animals were randomly assigned to two groups to undergo sham or the 2K1C surgical procedure under isoflurane-induced anesthesia; approval was granted by our institutional animal ethics committee (A2404, n =15 per group). Hemodynamic parameters including heart rate; systolic and diastolic blood pressure were monitored weekly for 6 weeks, using a volume-pressure tail cuff and a CODA pressure computer. Plasma concentrations of critical biomarkers of the renin-angiotensin system were quantified using standard ELISA assays and renal histopathological changes were assessed microscopically. Unilateral renal arterial stenosis caused marked renal atrophy, glomerulosclerosis and interstitial fibrosis, but a compensatory renal hypertrophy was observed in contralateral kidneys. Interestingly, unilateral renal arterial stenosis failed to induce hypertension over the six week period. The resistance to develop hypertension in the 2K1C group was associated with a significant decrease in total plasma renin (P = 0.023), an increase in the ratio of plasma angiotensin (1-7) to total renin (P = 0.034) and a decrease in the ratio of angiotensin II to total renin (P = 0.013). There were no changes in plasma electrolytes, glucose, creatinine or urea. These data demonstrate that adult male Lewis rats may have physiologically modulated the activation of the renin-angiotensin system to maintain a homeostatic balance and resist hypertension following unilateral renal artery stenosis.

ELECTROLYTE CHANGES RELATED TO MUSCLE PAIN AFTER RESISTANCE EXERCISES

ABSTRACT Introduction Resistance exercises (RE) performed at high intensity cause an inflammatory response and electrolyte abnormalities in blood plasma. Objectives To study the plasma electrolyte changes resulting from a high-intensity session of RE in untrained volunteers, and to correlate these with delayed onset muscle soreness (DOMS). Methods Twenty volunteers, aged 26.9 (±4.4) years, underwent an RE session. The workout (leg extension, squat and leg press) consisted of four sets of 10 maximum repetitions. Electrolytes (Na+, K+, Ca2+ e Mg2+) were evaluated before the training (baseline), immediately (0 min), and 30 minutes after the RE. The DOMS was assessed 24 hours after the sessions. Results The Na+ increased immediately after the RE and returned to normal after 30 min (p<0.001). After 30 min, K+ increased compared to baseline levels and immediately after the RE (p<0.001). Ca2+ and Mg2+ levels did not change throughout the study. Changes in Na+ and K+ levels were correlated immediately (r=-0.511; p=0.021) and 30 min (r=-0.455; p=0.049) after RE. Plasma concentrations of Na+ 0 min were correlated (r=-0.520; p=0.018) with the DOMS. Conclusion High-intensity RE in untrained volunteers leads to changes in plasma concentrations of Na+ and K+. Na+ concentrations immediately after RE were related to DOMS; individuals that presented smaller alterations in this electrolyte reported more muscular pain. Level of evidence II; Diagnostic Studies - Development of diagnostic criteria on consecutive patients (with universally applied reference “gold” standard).

Influence of measurement principle on total hemoglobin value

BackgroundTotal hemoglobin (tHb) measurement is indispensable for determining the patient’s condition (hemorrhagic vs. ischemic) and need for blood transfusion. Conductivity- and absorbance-based measurement methods are used for blood gas analysis of tHb. For conductivity-based measurement, tHb is calculated after converting blood conductivity into a hematocrit value, whereas absorbance measurement is based on light absorbance after red blood cell hemolysis. Due to changes in plasma electrolytes and hemolysis, there is a possibility that conductivity- and absorbance-based measurement methods may cause a difference in tHb.MethodsIn this study, test samples with controlled electrolyte changes and hemolysis were created by adding sodium chloride, distilled water or hemolytic blood to blood samples collected from healthy volunteers, and tHb values were compared between both methods.ResultsConductivity-based measurement revealed reduced tHb value (from 15.49 to 13.05 g/dl) following the addition of 10% sodium chloride, which was also reduced by the addition of hemolysate. Conversely, the addition of distilled water significantly increased tHb value than the expected value. In the absorbance method, there was no significant change in tHb value due to electrolyte change or hemolysis.ConclusionsWe have to recognize unexpected conductivity changes occur at all times when tHb is measured via conductivity- and absorbance-based measurement methods. The absorbance method should be used when measuring tHb in patients with expected blood conductivity changes. However, when using this method, the added contribution of hemoglobin from hemolytic erythrocytes lacking oxygen carrying capacity must be considered. We recognize that discrepancy can occur between conductivity- and absorbance-based measurement methods when tHb is measured.

Chemical composition, antioxidant activity, and diuretic effect of Moroccan fresh bee pollen in rats.

Aim:This study investigated the chemical composition, antioxidant activity, and diuretic effect of Moroccan aqueous extract of fresh bee pollen (AEFBP) in normal rats.Materials and Methods:The chemical composition of the extracted bioactive compounds was assessed using liquid chromatography with diode array detection coupled to electrospray ionization (ESI) tandem mass spectrometry (LC/DAD/ESI-MSn). 2,2-diphenyl-1-picrylhydrazyl and the reducing power were used to assess the antioxidant properties of the extract, together with the determination of total phenols and flavonoids. To assess the diuretic effect, 20 normal rats were divided into five groups: The first was a control group administered by distilled water (10 mL/kg body weight), the second group received furosemide (10 mg/kg body weight), the third group received 100 mg/kg body weight of AEFBP, the fourth group received 250 mg/kg body weight of AEFBP, and the fifth group received 500 mg/kg body weight of AEFBP for 30 days. Toward the end of this experiment, urine output was measured, and plasma and urine were sampled to analyze creatinine, potassium, chloride, and sodium levels.Results:N1,N5,N10-tri-p-coumaroylspermidine is a spermidine derivative and was the main compound in this sample, in a total of 19 compounds identified, including flavonoids, glucoside flavonoids, and methylated derivatives. Force feeding with the AEFBP induced a significant increase in urine output and urinary electrolyte levels with a dependent dose-effect without changes in plasma electrolytes, whereas furosemide decreased plasma potassium.Conclusion:Moroccan fresh bee pollen extract contains flavonols and spermidines that induce a potential antioxidant activity related to significant diuretic effect without changes in plasma composition.

Acute effect of a peritoneal dialysis exchange on electrolyte concentration and QT interval in uraemic patients.

Hemodialysis (HD) sessions induce changes in plasma electrolytes that lead to modifications of QT interval, virtually associated with dangerous arrhythmias. It is not known whether such a phenomenon occurs even during peritoneal dialysis (PD). The aim of the study is to analyze the relationship between dialysate and plasma electrolyte modifications and QT interval during a PD exchange. In 15 patients, two manual PD 4-h exchanges were performed, using two isotonic solutions with different calcium concentration (Ca++1.25 and Ca1.75++mmol/L). Dialysate and plasma electrolyte concentration and QT interval (ECG Holter recording) were monitored hourly. A computational model simulating the ventricular action potential during the exchange was also performed. Dialysis exchange induced a significant plasma alkalizing effect (p < 0.001). Plasma K+ significantly decreased at the third hour (p < 0.05). Plasma Na+ significantly decreased (p < 0.001), while plasma Ca++ slightly increased only when using the Ca 1.75++mmol/L solution (p < 0.01). The PD exchange did not induce modifications of clinical relevance in the QT interval, while a significant decrease in heart rate (p < 0.001) was observed. The changes in plasma K+ values were significantly inversely correlated to QT interval modifications (p < 0.001), indicating that even small decreases of K+ were consistently paralleled by small QT prolongations. These results were perfectly confirmed by the computational model. The PD exchange guarantees a greater cardiac electrical stability compared to the HD session and should be preferred in patients with a higher arrhythmic risk. Moreover, our study shows that ventricular repolarization is extremely sensitive to plasma K+ changes, also in normal range.

Electrolyte Supplementation Prior to Prolonged Submaximal Exercise Results in Decreased PCO2 and tCO2 During Exercise and Recovery

IntroductionElectrolyte supplementation prior to exercise is known to benefit both performance and recovery; however its effects on acid‐base status remain not well characterized. The purpose of this study was to use the physicochemical approach to provide a comprehensive time‐course of the acid‐base alterations that occur following pre‐exercise electrolyte supplementation in horses. It was hypothesized that electrolyte supplementation will attenuate the alkalosis occurring with prolonged moderate intensity exercise.MethodsIn a randomized crossover experiment four conditioned mares were given, via nasogastric tube, 3 L of a commercial electrolyte solution (ES; designed to fully replace sweat electrolyte and fluid losses), or water alone (Control), 1 hour before they exercised on a treadmill at 30% VO2max until voluntary fatigue (inability to keep pace with belt speed). Blood was sampled from jugular venous catheters at frequent intervals before, during, and until 20 h of exercise recovery, and analyzed for all dependent and independent plasma acid‐base variables. Differences (P&lt;0.05) over time and between groups were assessed by 1‐ or 2‐way repeated measures ANOVA.ResultsHorses exercised for 57.5 ± 10.3 and 72.5 ± 17.0 min and lost 2.73 ± 0.82 and 4.63 ± 1.35 L in Control and ES trials, respectively. ES horses had lower pCO2 and total carbon dioxide (TCO2) concentrations during exercise and early recovery. Control horses exhibited decreased [H+]. pCO2 was the primary contributor to changes in [H+] and [TCO2], while there were no differences in strong ion difference ([SID]) or total weak acid concentration ([Atot]).ConclusionsElectrolyte supplementation prior to prolonged exercise leads to sustained effects on equine acid‐base variables, even in the absence of significant changes in plasma electrolytes or hydration.Ethical Animal ResearchThe experiments and use of animals were approved by the University of Guelph Animal Care Committee, in accordance with the guidelines of the Canadian Council on Animal Care. Sources of funding: Ontario Horse Racing Industry Association and the Natural Sciences and Engineering Research Council of Canada. Competing interests: none.

Plasma Electrolyte and Hematological Changes after Marathon Running in Adolescents

The objective of this research is to study plasma electrolyte and hematological changes in adolescent runners completing a standard 42.2-km marathon run. Fifty adolescents (30 healthy males and 20 healthy females) between ages 13 and 17 yr participated in the study. The participants had to undergo a routine physical examination including ECG records. Blood was taken before the race, immediately after the race, and 24 h after the race to determine complete blood cell count and electrolyte concentration. Forty-seven runners completed the race with a mean finishing time of 4 h 57 min (range: 3 h 17 min 09 s to 6 h 14 min). None of the participants experienced an adverse medical event during or after the race. Only slight changes in plasma electrolytes without any cases of hyper- or hyponatremia and a marked increase in white blood cell count were demonstrated immediately after the race. At this time, the hemoglobin concentration and hematocrit were decreased (P < 0.05), indicating an approximately 11% increase in plasma volume. Some of these changes were still present 24 h postrace. No differences were observed between sexes. This is the first study evaluating plasma electrolyte and hematological changes in a relatively large sample of young runners completing a standard marathon. The presented findings indicate that well-trained and educated adolescent marathon runners are not at risk to develop clinically significant electrolyte or hematological changes.

Changes in plasma electrolytes during exercise in normal subjects--with special reference to the concentration of potassium and inorganic phosphate (Pi)

In 8 healthy adults, changes in plasma electrolyte levels (Na+, Cl-, Ca2+, Pi and lactate) and respiratory parameters (VE, VO2 and VCO2) were examined during incremental exercise on a treadmill. Na+, Cl- and Ca2+ increased significantly near the end of maximal exercise and the early phase of the recovery period. Considering the 14% decrease in plasma volume, the increases in Na+, Cl-, and Ca2+ were not significant, while the increases in K+, Pi and lactate were significant. During incremental exercise, the concentration of K+ significantly correlated with minute ventilation (r = 0.994, p < 0.0001). Two minutes after the completion of exercise, K+ decreased below the pre-exercise level. The inflection point of VE on VO2 appeared earlier than that of K+ on VO2. The results suggest that some other factor which may contribute to the control of ventilation during exercise should be considered in addition to K+. Lactate and Pi began to increase 5 and 8 minutes, respectively, after the start of exercise. Even after the completion of exercise, these two parameters remained significantly higher than the pre-exercise level. During incremental exercise, the concentration of Pi increased concomitantly with time, and significantly correlated with VE. On the other hand, in the early stage of exercise, the concentration of lactate remained at the pre-exercise level. These results suggest that the increase in plasma Pi is responsible for the state of metabolism in the muscle in addition to lactic acidosis.

Study on the adsorption of endotoxin and proinflammatory cytokines with HB-H-7 resin in vitro

To study the efficacy and safety of adsorption of endotoxin and proinflammatory cytokines with HB-H-7 resin in vitro. Static adsorption experiment: HB-H-7 resin was added into plasma of endotoxin-positive patients according to the ratio of 1;10. Then, they were put in a constant temperature water bath oscillator, and oscillated for 2 hours. Before and after the experiment, plasma endotoxin, proinflammatory cytokines, protein and electrolytes were detected, and the rate of 2-hour absorption was calculated. The experiment was repeated 10 times. Dynamic adsorption experiment: 5 ml resin was put into a self-made perfusion unit. Endotoxin-positive patients plasma (50 ml) was perfused for 2 hours. The flow rate of plasma was controlled at 4 ml/min with the infusion pump, and the plasma endotoxin was determined at 0, 30, 60 and 120 minutes after plasma hemoperfusion, and the absorption rates were calculated. The results were compared with static adsorption. The influence of temperature during adsorption was determined as follows. Perfusion method was similar with dynamic adsorption experiment. The perfusion units were either placed in a 37 centigrade water path or 25 centigrade (room temperature). Then, the plasma endotoxin was measured 2 hours after plasma perfusion, and the absorption rates were calculated. In static adsorption experiment, the plasma endotoxin and proinflammatory cytokines were significantly lower after adsorption with HB-H-7 resin adsorption (all P<0.05). The adsorption rates of endotoxin, tumor necrosis factor-alpha and interleukin-1, 6, 8 were 99.2%, 55.0%, 57.0%, 75.0%, 42.0%, respectively. Changes in protein were small (all P<0.05) , and there was no significant change in plasma electrolytes (all P>0.05). Dynamic adsorption rate was higher than that of static, but the differences were not significant (99.8% vs. 99.1%, P>0.05). There was no statistically significant difference between difference in temperature (37 centigrade vs. 25 centigrade, 99.8% vs. 99.9%, P>0.05). HB-H-7 resin effectively absorbs endotoxin and proinflammatory cytokines in vitro. Its adsorption rate for protein is lower, and it has no obvious effects on electrolytes.

New Year's Day

The changes in plasma electrolytes and blood pH and gases following the insufflation of air into the subarachnoid space for pneumoencephalography were investigated. The only significant change observed was a rapid fall of plasma potassium most evident at 60 minutes. A concomitant reduction of the urinary Na/K ratio supports the possibility that the change observed may be due to the stimulation of aldosterone secretion caused by this procedure, though its rapid occurrence and reversibility indicate that other influences might at least in part be responsible.

Changes in plasma electrolytes and Gill Histopathology in Wild Liza saliens from the Esmoriz-Paramos Coastal Lagoon, Portugal

The Esmoriz-Paramos is a lagoon of great ecological significance located on the Northwest coast of Portugal. The quality of water and sediment within this ecosystem has been gradually degraded due to the discharges of mostly untreated industrial waste and domestic sewage. Contaminants include heavy metals that can be taken up by fish from water, food, sediments, and suspended particulate material. Fish inhabiting polluted water bodies tend to accumulate many chemicals in high concentrations, even when the environmental contamination levels are low (Colombo et al. 1995). The leaping grey mullet (Liza saliens) is one of a few dominant species living in this environment. This species may contact xenobiotics in the water column or, when feeding, in the sediments. Previous studies have analyzed heavy metal concentrations in the water and sediments of this lagoon, and evaluated their bioaccumulation in L. saliens (Fernandes et al. 2007a, b). According to these studies, the seasonal range of metal concentrations in surface water was 0.003–0.031 mg Cu L, 0.006–0.811 mg Zn L and 0.01–0.026 mg Pb L, all mainly found in particulate matter. The main metals found in sediments were Cu, Zn and Pb, respectively 83, 241 and 87 mg kgd.w. The Cu and Zn concentrations in L. saliens liver were 262 and 89 mg kgd.w. and below the detection limit for Pb (0.073 ppm), whereas these concentrations in the gill were 9 mg Cu kg d.w.; 114 mg Zn kg d.w. and 0.6 mg Pb kg d.w. Also, significant age-related increase of metal concentrations in tissues, were noted, for Zn in gill and for Cu in liver and gill (Fernandes et al. 2007a). The gill is particularly sensitive to physical and chemical changes in the aquatic environment and it is the main target organ in fish for toxic waterborne heavy metals (McDonald and Wood 1993). Effects of metals on ionoregulatory gill functions have been well demonstrated, including regulation of plasma electrolytes (Mazon et al. 2002; Grosell et al. 2003; Martinez et al. 2004). The histological effects of metals on fish gill have also been studied in several fish species (Arellano et al. 1999; De Boeck et al. 2001). The mechanisms of acute Cu toxicity include the osmoregulatory disturbances involving Na, Cl and K uptake by the gill (Mazon et al. 2002; Grosell et al. 2003). Although the mechanisms of heavy metals toxicity are well known in acute exposure, the process may differ in chronic exposure (Handy 2003). The objectives of this study were to evaluate the plasma electrolyte concentrations of wild Liza saliens from the Esmoriz-Paramos lagoon and to assess the osmoregulatory responses and branchial histopathological changes related to chronic heavy metal exposure in this habitat.

Dehydration with Bowel Purgatives

Purpose: Dehydration-related complications from colon preparation have recently emerged as a vital issue in colonoscopy screening. Signs of dehydration include weight loss, postural changes in blood pressure (BP) and pulse rate (PR), dizziness, and headaches. To assess whether multiple classes of purgatives may lead to dehydration, signs were monitored in patients (pts) undergoing colonoscopy in 2 identically designed, randomized, multicenter, investigator-blinded studies. Methods: Pts scheduled for colonoscopy received either 4-L PEG solution (Cherry Flavor NuLYTELY®; Braintree Laboratories Inc, Braintree, Mass; n = 432) or NaP tablets (Visicol® Tablets; Salix Pharmaceuticals, Inc, Morrisville, NC; n = 427) for bowel preparation. Weight, postural changes in BP and PR, and adverse events (AEs) were recorded up to 7 days before colonoscopy (baseline), on the day of colonoscopy, and 48 to 72 hours postcolonoscopy. Postural hypotension was defined as a symptom-associated orthostatic increase of 30 beats/min in PR or an orthostatic decrease in systolic (≥25 mm Hg) or diastolic (≥20 mm Hg) BP. Results: On the day of colonoscopy, weight loss was evident in pts treated with 4-L PEG (2.4 ± 2.8 lb) and 40 NaP tablets (2.1 ± 3.3 lb). Pts regained the majority of lost weight within 3 days postcolonoscopy, but weights were still reduced compared with baseline levels (−0.7 ± 3.0 lb, PEG group; −0.3 ± 3.1 lb, NaP group). Fourteen (3.2%) pts in the PEG group and 21 (4.9%) pts taking NaP tablets reported light-headedness or dizziness. Similarly, 2.8% (n = 12) and 3.3% (n = 14) of pts treated with PEG and NaP, respectively, experienced headaches. Seven pts (4 and 3 pts in PEG and NaP groups, respectively) reported symptoms suggestive of postural hypotension but did not reach the predefined criteria. In both groups, slight changes in plasma electrolytes resolved by end of study. Conclusions: Mean weight loss after purgation with either PEG solution or NaP tablets was ∼2 lb. Return to baseline weight was not fully achieved 2 to 3 days postcolonoscopy. Data suggest that pts lose a similar amount of stool and fluid during purgation, regardless of the bowel preparation. The prolonged weight reduction, along with AEs such as light-headedness, dizziness, and headaches, suggests that dehydration may be a risk even several days postcolonoscopy. Thus, pts who are scheduling a colonoscopy should be advised of the importance of proper hydration prior to, during, and after bowel preparation. Complications of dehydration can be avoided.

Fluid shifts resulting from exercise in rats as detected by bioelectrical impedance.

This study was designed to investigate the immediate effect of exercise intensity and duration on body fluid volumes in rats throughout a 3-wk exercise program. Changes in the extracellular water (ECW) and total body water (TBW) volumes of rats were measured preexercise and postexercise using multiple frequency bioelectrical impedance analysis. Groups of rats were exercised at two intensities (6 m.min(-1) and 12 m.min(-1)) for two exercise times (60 min and 90 min) 5 d.wk(-1) during a 3-wk period. Changes in plasma electrolytes, glucose, and lactate resulting from the exercise were also measured on 3 d of each week. Each group of animals showed significant losses in ECW and TBW as a direct result of daily exercise. The magnitude of fluid loss was directly related to the intensity of the exercise, but not to exercise duration; although the magnitude of daily fluid loss at the higher intensity exercise (12 m.min(-1)) decreased as the study progressed, possibly indicating a training effect. At low-intensity exercise, there is a small but significant loss in both TBW and ECW fluids, and the magnitude of these losses does not change throughout a 3-wk exercise program. At moderate levels of exercise intensity, there is a greater loss of both TBW and ECW fluids. However, the magnitudes of these losses decrease significantly during the 3-wk exercise program, thus demonstrating a training effect.

Electrolyte changes in plasma and urine of athletes during acute and rigorous bed rest and ambulatory conditions.

Rigorous bed rest (RBR) induces significant electrolyte changes, but little it is not known about the effect of acute bed rest (ABR) (i.e., abrupt confinement to a RBR). The aim of this study was to measure urinary and plasma electrolyte changes during ABR and RBR conditions. The studies were done during 3 d of a pre-bed-rest (BR) period and during 7 d of an ABR and RBR period. Thirty male trained athletes aged, 24.4 +/- 6.6 yr were chosen as subjects. They were divided equally into three groups: unrestricted ambulatory control subjects (UACS), acute-bed-rested subjects (ABRS), and rigorous-bed-rested subjects (RBRS). The UACS group experienced no changes in professional training and daily activities. The ABRS were submitted abruptly to a RBR regimen and without having any prior knowledge of the exact date and time when they would be subjected to an RBR regimen. The RBRS were subjected to an RBR regime on a predetermined date and time known to them from the beginning of the study. Sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and phosphate (P) in plasma and urine, plasma renin activity (PRA) and plasma aldosterone (PA), physical characteristics, peak oxygen uptake, and food and water intakes were measured. Urinary Na, K, Ca, Mg, and P excretion and plasma Na, K, Mg, Ca, and P concentration, PRA, and PA concentration increased significantly (p < or = 0.01), whereas body weight, peak oxygen uptake, and food and water intakes decreased significantly in the ABRS and RBRS groups when compared with the UACS group. However, urinary and plasma Na, K, Mg, P, and Ca, PRA, and PA values increased much faster and were much greater in the ABRS group than in the RBRS group. Plasma and urinary Na, K, Ca, Mg, and P, PRA and PA levels, food and water intakes, body weight, and peak oxygen uptake did not change significantly in the UACS group when compared with its baseline control values. It was shown that RBR and ABR conditions induce significant increases in urinary and plasma electrolytes; however, urinary and plasma electrolyte changes appeared much faster and were much greater in the ABRS group than the RBRS group. It was concluded that the more abruptly motor activity is ended, the faster and the greater the urinary and plasma electrolyte change.

Experimental hypocalcemia induced by hemodialysis in goats.

To evaluate whether hemodialysis with a dialysate containing no calcium (Ca-free HD) can induce hypocalcemia and restore the clinical signs and blood biochemical changes in naturally occurred hypocalcemic disorder in ruminants, the clinical signs and the changes in plasma electrolytes and minerals concentrations were observed in goats during 6-hr hemodialysis. The four goats received hemodialysis with the dialysate containing calcium (Ca HD), and 10 days later they had Ca-free HD. The plasma ionized Ca (Ca++) and total Ca (TCa) concentrations were not affected by Ca HD, whereas the levels significantly decreased during whole period of Ca-free HD. The Ca++ and TCa concentrations were 0.69+/-0.06 mmol/l and 5.9+/-0.3 mg/dl at 6 hr of Ca-free HD, respectively. The clinical signs observed during Ca-free HD seemed to resemble to those in naturally occurred hypocalcemic cases that were reported previously. Therefore, Ca-free HD was suggested to be one of the possible methods to induce experimental hypocalcemia in ruminants.

Acute and subacute toxicity of tyramine, spermidine, spermine, putrescine and cadaverine in rats

The acute and subacute toxicity of five biogenic amines—tyramine, spermidine, spermine, putrescine and cadaverine-were examined in Wistar rats. Tyramine and cadaverine had a low acute oral toxicity of more than 2000 mg/kg body weight. Putrescine had an acute oral toxicity of 2000 mg/kg body weight and spermidine and spermine each of 600 mg/kg body weight. All amines investigated caused a dose-related decrease in blood pressure after intravenous administration, except for tyramine, where an increase was found. In 6-wk studies the biogenic amines were administered in the diet to groups of 10 male and 10 female rats. Tyramine and cadaverine were given at levels of 0, 200, 2000 or 10,000 ppm, spermine and putrescine at levels of 0, 200, 2000 or 5000 ppm and spermidine at levels of 0, 20, 200 or 500/1000 ppm in the first study and at levels of 0 or 10,000 ppm in a second study. Spermine was the most toxic. The high dose level showed a great number of changes, such as emaciation, aggressiveness, convulsions and paralysis of the hind legs. Growth, food intake and water intake were considerably decreased. Slight anaemia (males) and changes in plasma clinical chemistry occurred. The relative weights of the thyroid, adrenals, spleen and heart were increased and that of the liver decreased. Impaired kidney function, together with renal histopathological changes and changes in plasma electrolytes and urea, occurred with spermine. Histopathological examinations also revealed decreased glycogen content in the liver, reduction of spermatogenesis, severe depletion of splenic white pulp, acute involution of the thymus and moderate myocardial degeneration in the heart. Myocardial degeneration was also seen in one mid-dose male. Adverse effects were also observed in the top dose groups of all other amines. Decreased body weights associated with diminished food intake were generally seen. Slight increases in packed cell volume, haemoglobin concentration and thrombocytes occurred with cadaverine. With spermidine, decreased plasma creatinine, calcium and inorganic phosphate were observed and decreased potassium levels with cadaverine. The no-observed-adverse-effect level was 2000 ppm (180 mg/kg body weight/day) for tyramine, cadaverine and putrescine, 1000 ppm (83 mg/kg body weight/day) for spermidine and 200 ppm (19 mg/kg body weight/day) for spermine.

Fractional reabsorption of calcium, magnesium and phosphate in the kidneys of freshwater North American eels (Anguilla rostrata LeSueur) following removal of the corpuscles of Stannius.

Renal function was observed in freshwater North American eels (Anguilla rostrata LeSueur) 2 weeks after the removal of the corpuscles of Stannius. There was a positive linear correlation between glomerular filtration rates and urine flow rates in both sham-operated and stanniectomized eels but there was no difference in slope or elevation between the two groups nor did urine flow rates ever exceed glomerular filtration rates. Osmolar clearance and free-water clearance were unchanged following stanniectomy. Plasma Ca2+ and K+ concentrations increased and plasma Mg2+, phosphate, Na+ and Cl- concentrations decreased following stanniectomy. Plasma ultrafilterable Ca increased and ultrafilterable Mg decreased after stanniectomy but neither changed relative to its total plasma concentration. Stanniectomy was followed by a decreased renal tubular reabsorption of Mg2+ relative to the amount filtered (CMg/CIn); the same applies to CNa/CIn. Even though the filtered load of Ca increased in conjunction with the predictable hypercalcemia, there was no change in the fraction of filtered Ca reabsorbed. Net tubular secretion of phosphate was observed in both sham-operated and stanniectomized eels together with a slight increase in Cphos/CIn following stanniectomy. Some or all of these changes in plasma electrolytes and/or the modified renal transport of Na+, Mg2+ and possibly phosphate may be caused by the changes in cardiovascular function that were recently shown to follow stanniectomy.

Amylin Stimulates Plasma Renin Concentration in Humans

Although insulin resistance and hypertension are commonly associated, the underlying cause for this association remains unknown. Plasma concentrations of the recently described hormone amylin, which is cosecreted with insulin by the pancreatic beta cell, are reported to be elevated in various states of insulin resistance, including hypertension and obesity. Preliminary studies by our group have suggested that there are amylin binding sites in the kidney. In nine healthy humans an infusion of human amylin that resulted in steady state plasma amylin levels in the subnanomolar range led to significant increases in plasma renin and aldosterone concentrations. These changes occurred in the absence of significant changes in plasma electrolytes, catecholamines, vasopressin, total renin, or osmolality. Diastolic pressure at 30 minutes and plasma glucose at 60 minutes rose modestly. Since amylin has both metabolic and renal actions, this peptide may be an important link between hypertension, insulin resistance, and the renin-angiotensin system.

Haemodynamic and metabolic effects of short term administration of synthetic sex steroids in humans.

Synthetic sex steroid administration is a major cause of iatrogenic hypertension but little is known of the haemodynamic or metabolic consequences of these steroids. This study examined the short term blood pressure, volume and metabolic consequences of 5 day administration of synthetic androgen to normal men and synthetic oestrogen or progestogen to normal women. Healthy subjects (8 women, 6 men) on a constant diet took part in each of 3 studies. Males received testosterone undecanoate 120 mg/day (n = 6) and females either ethinyloestradiol 0.3 mg/day (n = 5) or norethisterone 15 mg/day (n = 6) for 5 days in the last week of the cycle. Norethisterone increased lying (+7 mmHg) and standing (+8 mmHg) systolic pressure but the other steroids did not alter blood pressure. All 3 treatments increased body weight. There were no consistent changes in plasma electrolytes or glucose with any steroid, and no urinary sodium retention or changes in urine Na:K ratio. Haematocrit fell on ethinyloestradiol but no steroid significantly increased plasma volume (measured as volume of distribution of 125I human serum albumin). Renin substrate and cortisol rose and renin concentration fell on ethinyloestradiol. These studies suggest that the progestogen component may contribute to the blood pressure raising effects of oral contraceptives.