Erythrocyte membrane cation carrier in mania.

Erythrocyte sodium and potassium concentrations, erythrocyte membrane ATPase (Na-K specific and non-specific) and the rate of potassium influx into erythrocytes (ouabain-sensitive and insensitive) were estimated in a group of female patients suffering from mania and repeated on about two thirds of them when they had recovered. With recovery there was a statistically significant increase in the erythrocyte ouabain-sensitive potassium influx. The other parameters showed no significant overall change with recovery but the initial severity correlated significantly and negatively with the change in erythrocyte Na-K ATPase with recovery. The changes that occurred in the erythorcyte sodium concentration and Na-K ATPase activity were not random since they correlated significantly with changes in the active potassium influx.     

Erythrocyte membrane cation carrier, relapse rate of manic-depressive illness and response to lithium.

Biochemical studies of manic-depressive psychosis usually correlates biochemical findings with current affective state and hence any significant findings could be secondary to mood change. The present study attempts to correlate measures of the erythrocyte membrane cation carrier with clinical events, remote in time from the biochemical assay. Eprythrocyte sodium concentration, ouabain-sensitive potassium influx and Na-K ATPase were estimated in 11 patients before and after the cross-over point in a 2-year double blind clinical trial ratio tended to suffer most episodes of affective illness in the 2 years. Patients who had a low initial Na-K ATPase or a high initial flux sodium ATPase ratio, or in whom this ratio fell most with lithium or whose Na-K ATPase rose most with lithium, clinically responded best to lithium.     

Effects of sodium and potassium concentrations and pH on equine erythrocyte volume and deformability

During strenuous exercise, equine erythrocyte deformability is transiently decreased. Decreased deformability is associated with increased cell volume, decreased cell density and increased intracellular sodium, potassium and chloride concentrations. To better understand these changes, we attempted to reproduce exercise-associated changes in erythrocytes in vitro by adjusting plasma sodium, potassium and pH to levels which occur during racing activity. Increasing plasma sodium to 145 meq/1 and plasma potassium to 8 meq/1 resulted in decreased erythrocyte filterability, increased cell volume, and increased intracellular sodium, potassium and chloride. Incubation of erythrocytes with frusemide and bumetanide, but not ouabain or [(dihydroindenyl)oxy]alkanoic acid (DIOA), attenuated these changes. Decreasing plasma pH to 7.0 also decreased erythrocyte filterability, increased cell volume, and increased intracellular concentrations of sodium, potassium and chloride. Ouabain, but not frusemide or bumetanide, prevented the decrease infilterability and attenuated the increase in intracellular sodium. Addition of DIOA exacerbated the effect of pH on erythrocyte filterability. Therefore, exercise-associated changes in erythrocyte deformability, size and electrolyte concentration can be reproduced in vitro by increasing plasma sodium and potassium concentrations and by decreasing pH.     

Lithium and erythrocyte membrane cation carrier studies in normal and manic depressive subjects.

Changes in the erythrocyte membrane cation carrier following lithium ingestion in normal human subjects were studied; ouabain sensitive potassium influx fell significantly during the lithium treated phase. Lithium was fed to rats and no change in erythrocyte Na-K ATPase was shown. These findings contrast with studies of lithium in manic depressive psychosis. The fluctuations in the erythrocyte membrane cation carrier were studied in 5 normal subjects over 12 weeks and the correlations between the parameters calculated. The erythrocyte sodium concentration correlated positively with the ouabain sensitive potassium influx. This too contrasts with findings in manic depressive psychosis.     

Prediction of clinical course of bipolar manic depressive illness treated with lithium

A group of bipolar manic depressive patients attending a routine lithium clinic were investigated. The results suggest that, when on treatment with lithium, manic depressive patients with a good prognosis tend to have a higher erythrocyte Na-K ATPase and higher plasma and erythrocyte lithium concentrations than those with a poor prognosis. There was no evidence to suggest that the erythrocyte: plasma lithium ratio was useful in predicting clinical response to lithium therapy. There was also a positive correlation between plasma lithium concentration and Na-K ATPase activity, confirming that in manic depressive subjects lithium produces a rise in erythrocyte Na-K ATPase activity.     

Effects of thyroid hormones on heart and kidney functions

Thyroid hormones affect the functions of several organs including the heart and kidney. Using isolated left papillary muscles we have investigated the action of thyroid hormones on the mechanical and electrical properties of the heart. We found that pure hypothyroidism causes a depression in contractile and electrical parameters, but we noticed that superimposed hypoparathyroidism accounts for the marked prolongation in contractile kinetics and action potential duration. At kidney level we have shown that thyroid hormones affect proximal tubular sodium transport and this effect is only partially mediated by the action of thyroid hormones on Na-K-ATPase activity. Using the micropuncture technique, we hypothesized that the early effect of thyroid hormone action is on the potassium permeability of proximal tubular cell membrane. This latter effect would explain the increase in isotonic fluid reabsorption through an increase in the driving force for sodium. Finally, hypothyroid patients have a decrease in glomerular filtration rate and renal plasma flow that are completely reversed by thyroxine administration. On the other hand, hyperthyroid subjects exhibit a significant increase in both parameters.     

Sodium and lithium transport and steroid hormones of the adrenal glands

Erythrocyte Na-Li countertransport was determined in 42 patients with essential hypertension (EH), 36 patients with hypertensive chronic diffuse glomerulonephritis, 47 patients with chronic pyelonephritis, 19 patients with renovascular hypertension and 9 patients with primary aldosteronism (PA). None of PA patients was treated with verospiron. Individual assessment of Na-Li exchange was made in 15 patients with nonspecific aorto-arteritis (NAA), untreated by steroid hormones, and in 2 glucocorticoid-treated NAA patients. Na-Li exchange parameters were compared before and after surgery in 7 patients with arterial hypertension (AH). Mean rate of Na-Li countertransport was nearly twice as high in EH patients as compared to the respective rate in patients with renal AH, whereas the difference in mean countertransport rates was not significant between EH and PA patients. Increased Na-Li exchange rate went down to normal values in a PA patient, while postoperative hydrocortizone treatment increased this rate in a patient with pheochromocytoma. In the remaining patients with symptomatic hypertensions (renovascular hypertension, pyelonephritic granular kidney, aortic coarctation, pheochromocytoma), Na-Li exchange remained unchanged after surgery. The rate of Na-Li exchange was increased in prednisolone-treated NAA patients, as compared to NAA patients receiving no glucocorticoids. The level of Na-Li exchange was stable over 9-18 months in AH patients with normal plasma aldosterone levels. No effects of obsidan, corinfar, clophelin, furosemide, hypothiazide and triampur on Na-Li exchange were identified.     

Ionic transport in individual renal epithelial cells from adult and young rats

Renal epithelial cells were isolated from the outermost superficial cortex of adult and young rats. The cells, likely of proximal origin, were plated on silicon pieces, and cultured during 1-3 days. Intracellular content and concentrations of K, Na, Cl, and P, and the kinetics of change in intracellular content, after inhibition of Na-K ATPase by incubation with ouabain or in K-free medium, were measured in individual cells in small populations using electron probe analysis. In control medium, concentrations in mM were approximately: K, 130; Na, 15; Cl, 28; P, 140. After 6 h inhibition of Na-K ATPase, cells exchanged all K for Na, and the intracellular Na concentration increased to 139 mM in K-free medium. The Cl concentration increased at most to 46 mM. The sum of intracellular K + Na + Cl did not increase more than 25% after 24 h incubation in K-free medium. There were no differences in intracellular K, Na, and Cl for adult and young rat cells in similar conditions. The half-times of K efflux and Na influx after inhibition of Na-K ATPase measured in adult rat were approximately 16-20 min. In the absence of serum, in K-free medium, the half-times of K efflux and Na influx in young rat cells were approximately 30 min, significantly higher than the half-time in the presence of serum, and with ouabain, being approximately 13 min. Histograms of distributions of K and Na content showed that the cells behaved as a single functional population. Ouabain Ki was estimated to be 10(-4) M. After 24 h preincubation in K-free medium, when returned in 5 mM K-containing medium, adult rat cells recovered rapidly normal intracellular K and Na concentrations. Using this approach, expression of the kinetics ionic transport properties of renal epithelial cells during development, and the hormonal influences on terminal differentiation may be studied.     

G-protein beta3-subunit gene variant,blood pressure and erythrocyte sodium/lithium countertransport in essential hypertension

Recently, a C825T polymorphism in the gene coding for the beta3 subunit of G proteins (GNB3) has been described in cells from patients with essential hypertension and enhanced Na+/H+ exchange activity. This study aims to evaluate the association between the 825T allele and activity of erythrocyte sodium/lithium countertransport (Na+/Li+ CT) and other sodium transport systems in red blood cells from patients with essential hypertension. A group of 77 patients (36 male, 41 female; aged 51.7 +/- 1.1 years) was studied. The maximal rates (Vmax) of Na+/Li+ CT, Na+/K+/Cl- cotransport and Na+K+ ATPase were evaluated in erythrocytes from all the patients. They were genotyped for the C825T polymorphism by a polymerase chain reaction (PCR) method, followed by digestion with BseDI. Body mass index (BMI) was higher in CT+TT patients than in CC patients (28.9 +/- 0.5 vs. 27.0 +/- 0.7 kg/m2; P=0.023). Hypertensives with the T allele (CT+TT genotypes) showed significantly higher systolic blood pressure (BP) values (156.9 +/- 2.1 vs. 148.9 +/- 2.8 mmHg; P=0.024), whereas differences in diastolic BP did not reach statistical significance (96.4 +/- 1.0 vs. 94.0 +/- 1.1 mmHg; P=0.120). No differences in the Vmax of Na+/Li+ CT between the genotypes was seen (CC: 236 +/- 19 and CT+TT 277 +/- 23 mmol/L cells per h; P=0.221). Similarly, no differences were detected in the Vmax of erythrocyte Na+/K+/Cl- cotransport and Na+K+ ATPase among the genotypes. There was no appreciable association between the G-protein beta3-subunit C825T polymorphism and erythrocyte Na+/Li+ CT and other sodium transport systems in the hypertensive patient sample studied; however, those with the T allele were more obese and had more severe systolic hypertension.     

Abnormal red-cell calcium pump in patients with idiopathic hypercalciuria

Idiopathic hypercalciuria is a common disorder whose inheritance suggests an enzyme abnormality in calcium transport. We measured calcium-magnesium-ATPase activity in erythrocytes from 38 patients (mean age [+/- SEM], 40 +/- 2.1 years) with idiopathic hypercalciuria (24-hour urinary calcium excretion greater than or equal to 0.1 mmol per kilogram of body weight) and a history of multiple calcium oxalate kidney stones. As compared with 41 healthy controls, the patients with hypercalciuria had increased erythrocyte-membrane calcium-magnesium-ATPase activity (64.2 +/- 2.19 vs. 51.6 +/- 1.91 nmol of ATP split per milligram per minute; P less than 0.01) and increased sodium-potassium pump activity (6866 +/- 233 vs. 6096 +/- 228 mumol of sodium per liter of red cells per hour; P less than 0.05). No significant difference between the two groups was found in erythrocyte sodium-potassium cotransport, sodium-lithium countertransport, or potassium content. In 66 patients with kidney stones (38 with hypercalciuria and 28 with normal calcium excretion), 24-hour urinary calcium excretion correlated with calcium-magnesium-ATPase activity (r = 0.46, P less than 0.001). Erythrocyte calcium-magnesium-ATPase activity remained unchanged in eight subjects studied after four months on a low-calcium diet. A study of 30 healthy families found significant correlations between mean values in parents and those in offspring for calcium-magnesium-ATPase (r = 0.68, P less than 0.001) and urinary calcium excretion (r = 0.45, P less than 0.02), with no significant correlations between parents with respect to these measures (r = 0.27 and r = 0.08, respectively). We conclude that abnormalities in erythrocyte calcium-magnesium-ATPase activity may represent an inherited defect in calcium transport related to the cause of idiopathic hypercalciuria.     

The enzymes of the enterocyte. Prospects for a functional exploration]

The authors recall the enzymatic activity and transport activities which were localised in the glycocalyx, the microvillous membrane, the intracellular compartment and the basolateral membrane of the enterocyte. The relationships between the processes of digestion and absorption, on the one hand, active transport, energy metabolism and sodium and potassium dependent ATPase, on the other hand are considered. The application of these data to functional investigation of the enterocyte is discussed, emphasizing the complementary character of the biological tests used currently and the importance of sodium and potassium dependent ATPase in the phenomena of active transport.     

Activation of sodium transport in human erythrocytes by β-adrenoceptor stimulation in vivo

Summary -adrenoceptor stimulation in vivo shifts potassium into the cells. To examine whether human erythrocytes participate in this process, we measured, along with serum or plasma potassium, the concentrations of potassium and sodium in erythrocytes. -adrenoceptor stimulation was obtained by infusion of either fenoterol or hexoprenaline into 6 volunteers at rest or by endogenous amines provoked in 14 volunteers during ergometric exercise. Metabolic effects were followed at rest on serum insulin, Cpeptide, and growth hormone levels, and during exercise on pH and on lactate concentration in blood. The potassium concentration (mean ±S.E.M.) dropped (p<0.001) in serum from 4.64±0.37 to 3.19±0.43 mmol·l^–1 in the first hour at rest and in plasma from 5.70±0.93 to 4.63±0.45 in 90 sec directly after exercise. The concentration of erythrocyte sodium dropped (p<0.001) from 9.68±0.73 to 8.81±0.62 mmol·l^–1 in cells and from 9.62±1.16 to 8.55±1.24 during exercise for 90 s, respectively. Changes in the concentration ratio of cellular sodium to potassium confirmed this sodium shift.An increased sodium transport in erythrocytes due to -adrenoceptor stimulation in vivo appears to complement a shift of serum potassium into the cells and may be mediated by the membranebound sodium, potassium ATPase.Supported by the Deutsche Forschungsgemeinschaft, grant Bo 425/8-5     

A biometrical study of the relationship between sodium-lithium countertransport and triglycerides

We addressed the question: Is there evidence that allelic variation in a single unmeasured gene that has a large effect on maximal activity of erythrocyte sodium-lithium countertransport (Na-Li CNT) also has pleiotropic effects on variation in plasma triglyceride levels? Complex segregation analysis models that included plasma triglyceride levels as a covariate were considered as explanations for interindividual variation in Na-Li CNT. A sample of 711 healthy adults from 254 pedigrees enrolled in the Rochester Family Heart Study was selected for this study. The majority of the pedigrees supported the hypothesis that variations in a single unmeasured non-transmitted environmental factor have large effects on the Na-Li CNT distribution. Only gender-specific first-order covariate parameters were necessary in the complex segregation models suggesting that the form of the relationship between Na-Li CNT and plasma triglyceride level was not influenced by variation in the inferred environmental factor with large effects. Stratification of the sample by this inferred environmental factor resulted in three classes of individuals with significant differences in the distributions of coronary heart disease risk factor traits, as well as interindividual variation in both Na-Li CNT and plasma triglyceride levels. These results, along with other observations from the Rochester Family Heart Study sample, emphasize the complex and multifactorial nature of the causes of interindividual variation in Na-Li CNT. Our study further suggests that new research strategies are needed for studying the relationships between genetic and environmental variation and variation in quantitative traits such as Na-Li CNT that have been identified as risk factors for hypertension.     

老化红细胞变形能力与膜钙依赖中性蛋白酶活性的关系

研究表明,老化红细胞变形能力明显降低,且其降低与血红蛋白浓度增高及膜弹性降低有关［１］。红细胞膜钙依赖中性蛋白酶（Ｃａｌｐａｉｎ）和它的内源性抑制剂（Ｃａｌｐａｓｔａｔｉｎ）形成红细胞中一个蛋白水解系统,参与红细胞中的信号传导,调节细胞形状、体积和细胞膜通透性,与高血压、细胞老化等生理、病理现象密切相关。Ｃａｌｐａｉｎ可限制性水解红细胞膜骨架蛋白和其它膜内蛋白,导致红细胞损伤［２,３］。而老化红细胞变形能力降低与Ｃａｌｐａｉｎ的关系尚不清楚,为此我们检测了４２例健康人老化及年轻红细胞变形能力、Ｃ…     

Changes of sodium transport in erythrocytes of the maturing rabbit.

The red blood cells of New Zealand white rabbits have a low sodium and high potassium content. As the animals mature, the sodium concentration rises and the potassium content falls; studies of red cells from a group of five young and five mature animals revealed a highly significant increase of cell sodium with age that was associated with a significant fall in the rate of ouabain-inhibited active sodium efflux. This difference was still seen when the sodium concentration within the cells from old and young animals was equalized and elevated to saturating levels for active pump efflux. Total sodium efflux, however, increased significantly with age as did total sodium influx so that a steady state was reached. Ouabain-sensitive ATPase activity fell significantly in the cell membranes from older animals and ouabain-insensitive ATPase increased with age. The survival time of 51Cr-labeled red cells was significantly longer in old than in young animals and it is concluded that as the rabbit matures its red cells survive for a longer period and this is associated with the changes of sodium transport and ATPase activity that have been documented.     

Thyroid calorigenesis in isolated, perfused rat liver: minor role of active sodium-potassium transport.

1. The effects of ouabain on hepatic oxygen uptake, cell membrane potential, and Na-K transport were examined at 37 degrees C during non-recirculating perfusion of isolated livers from fasted normal rats and rats treated with triiodothyronine (T3). The perfusate was Krebs-Ringer bicarbonate buffer containing albumin and bovine erythrocytes. 2. Treatment with T3 increased the rate of hepatic oxygen uptake by 30% (i.e. by 0-83 (micromole/min) per gram liver). 3. After shifting to perfusate containing 2-5 mM ouabain, a 4-5 mV depolarization and maximal rates of net hepatic K release and Na uptake occurred within 2 min in both thyroid states. These changes were not accompanied by any significant change in the rates of hepatic oxygen uptake. 4. T3-treatment increased the maximal, post-ouabain net flux of K by 29% (i.e. by 0-52 (muequiv/min) per gram liver). The T3-indlced increase in the net flux of Na (19%) did not achieve statistical significance. 5. In either thyroid state, the observed passive fluxes of Na and K were calculated to be balanced by active vluxes at the expense of 5-6% of the observed rate of hepatic oxygen uptake. 6. The results indicate that hyperthyroidism may enhance the rate of hepatic Na-K transport, but the energy expenditure due to this process appears to be too small to make any important contribution to thyroid calorigenesis in perfused rat liver.     

Hormonal regulation of electrolyte and water transport in the Colon

Summary The colon participates in water and electrolyte homoiostasis by the absorption of sodium (Na) and water as well as by potassium (K) secretion. The primary step of colonic transport is the active Na transport via a transcellular route. Steroidal hormones considerably increase Na absorption by utilizing two mechanisms: (1) passive Na entry into the cells is enhanced by an increased membrane permeability; (2) active transport capacity is increased by a stimulation of ATPase synthesis. Mineralocorticoid versus glucocorticoid actions of steroids have not yet been clearly differentiated; parallel influences are possible. Active chloride (Cl) secretion is found in the colon under certain pathological conditions and is induced by a number of factors, e.g., hormones produced by pancreas tumors. Cellular events involve a rise of intracellular cAMP and calcium (Ca) concentrations, and altered Cl permeabilities. Functional changes of colonic epithelial cells caused by hormones assume a significant role in the etiology of diarrhea, as well as in compensatory processes by which an intestinal loss of electrolytes and water is prevented.     

Impaired sodium levels in the suprachiasmatic nucleus are associated with the formation of cardiovascular deficiency in sleep-deprived rats

Biological rhythms are a ubiquitous feature of all higher organisms. The rhythmic center of mammals is located in the suprachiasmatic nucleus (SCN), which projects to a number of brainstem centers to exert diurnal control over many physiological processes, including cardiovascular regulation. Total sleep deprivation (TSD) is a harmful condition known to impair cardiovascular activity, but the molecular mechanisms are unknown. As the inward sodium current has long been suggested as playing an important role in driving the spontaneous firing of the SCN, the present study aimed to determine if changes in sodium expression, together with its molecular machinery (Na-K ATPase) and rhythmic activity within the SCN, would occur during TSD. Adult rats subjected to different periods of TSD were processed for time-of-flight secondary ion mass spectrometry, Na-K ATPase assay, and cytochrome oxidase (COX) (an endogenous bioenergetic marker for neuronal activity) histochemistry. Cardiovascular dysfunction was determined through analysis of heart rate and changes in mean arterial pressure. Results indicated that, in normal rats, strong sodium signals were expressed throughout the entire SCN. Enzymatic data corresponded well with spectrometric findings in which high levels of Na-K ATPase and COX were observed in this nucleus. However, following TSD, all parameters including sodium imaging, sodium intensity as well as COX activities were drastically decreased. Na-K ATPase showed an increase in responsiveness following TSD. Both heart rate and mean arterial pressure measurements indicated an exaggerated pressor effect following TSD treatment. As proper sodium levels are essential for SCN activation, reduced SCN sodium levels may interrupt the oscillatory control, which could serve as the underlying mechanism for the initiation or development of TSD-related cardiovascular deficiency.     

The calcium content of human erythrocytes

1. The calcium content of human erythrocytes, after removal of the buffy coat and washing free from plasma with isotonic sodium chloride, has been determined by atomic absorption spectrophotometry. The mean value found for normal subjects was 0.634 mug/ml. of packed erythrocytes (0.0158 mug-atom/ml.). The corresponding values for magnesium and zinc were 79.7 and 20.1 mug/ml., respectively.2. The calcium is considered to be mostly and perhaps exclusively located in the erythrocyte membrane, since, after osmotic haemolysis, the same amount was found in the ghost cells as was present in the erythrocytes from which they were prepared. By contrast, magnesium and zinc, which are essentially intracellular, were lost to the extent of about 96 and 92%, respectively.3. About 90% of the calcium was removed from erythrocytes by washing with isotonic sodium chloride containing 5 mM ethylenediaminetetraacetate (EDTA), or other complexing agents of high stability constant for calcium. A small fraction of the magnesium but none of the zinc was removed by this treatment.4. Other complexing agents of lower stability constant removed somewhat less calcium from the erythrocytes. Citrate was totally ineffective.5. The buffy coat had a high calcium content, but this could not be removed by washing with EDTA.6. Calcium was also determined in trichloroacetic acid extracts of ghost cells after ashing and treatment with bis-(o-hydroxyphenylimino)-ethane and measuring the red complex spectrophotometrically. The values obtained confirmed the atomic absorption measurements.     

In-vivo quantification of myocardial Na-K pump rate during beta-adrenergic stimulation of intact pig hearts

Maintenance of adequate electrical activity of the heart depends critically on the ability of the Na-K pump to compensate for normal passive sodium and potassium fluxes. Using sudden injections of [3H]ouabain into the left coronary artery in anaesthetized open-chest pigs, we monitored transient changes in myocardial potassium balance by PVC-valinomycin mini-electrodes. When related to the number of pumps blocked and fractional inhibition, these data provided estimates of total Na-K pump capacity as well as actual pump rate and perturbations of the Na-K balance. Experiments were performed in hearts with and without intracoronary isoprenaline infusion (2.5 nmol min-1). After injection of 120 nmol [3H]ouabain into the left coronary artery, myocardial [3H]ouabain concentrations were 118 (74-178) and 103 (76-145) pmol g-1 and total concentrations of [3H]ouabain binding sites were 893 (752-1076) and 785 (691-877) pmol g-1 (median, 95% confidence interval) in isoprenaline-treated and control hearts respectively (differences not significant). The [3H]ouabain injection caused a net potassium release of 81 (56-132) and 43 (23-75) mumol 100 g-1 (median, 95% confidence interval) in isoprenaline-treated and control hearts respectively (n = 6-8; significance of difference, P = 0.03). Na-K pump rate estimated from mono-exponential release curves was 6363 (3942-10,858) K+ ions min-1 site-1 during beta-adrenoceptor stimulation and 2514 (1380-4322) in control (significance of difference, P = 0.03). This corresponds to 40 and 16%, respectively, of the maximum possible pump rate determined from ATP hydrolysis. Comparison of accumulated potassium release and relative Na-K pump rate indicates that catecholamines enhance the sensitivity of the Na-K pump for intracellular sodium.