Red Cell Sodium Research Articles

Red blood cell sodium transport in patients with cirrhosis.

Patients with advanced cirrhosis have abnormal sodium homoeostasis. The study was undertaken to quantify the sodium transport across the plasma membrane of red blood cells (RBC) in patients with cirrhosis. RBC efflux and influx of sodium were studied in vitro with tracer (22) Na(+) according to linear kinetics in 24 patients with cirrhosis and 14 healthy controls. The sodium efflux was modified by ouabain (O), furosemide (F) and a combination of O and F (O+F). RBC sodium was significantly decreased (4·6 versus control 6·3mmoll(-1) , P<0·001) and directly related to serum sodium (r=0·57, P<0·05). The RBC fractional sodium efflux was higher in patients with cirrhosis (+46%, P<0·01) compared to controls. Inhibition in both high (145mmoll(-1) )- and low (120mmoll(-1) )-sodium buffers showed that the F-insensitive sodium efflux was twice as high in cirrhosis as in controls (P=0·03-0·007), especially the O-sensitive, F-insensitive efflux was increased (+ 225%, P=0·01-0·006). Fractional F-sensitive transport was normal in cirrhosis. RBC sodium influx was largely normal in cirrhosis. In conclusion, RBC sodium content is reduced in patients with cirrhosis with a direct relation to serum sodium. Increased RBC sodium efflux is especially related to ouabain-sensitive, furosemide-insensitive transport and thus most likely due to upregulated activity of the sodium-potassium pump. The study gives no evidence to an altered intracellular/extracellular sodium ratio or to a reduced fractional furosemide-sensitive sodium transport in cirrhosis.

PP087. Deep trial secondary analysis: Digoxin immune fab fragment treatment has additional benefits in endogenous digitalis-like factor positive preeclamptic women

A double blinded placebo controlled clinical trial of a commercial digoxin immune Fab fragment (DIF) in preeclamptic (PE) women provided some benefit to treated subjects (1). In that study DIF, relative to placebo, prevented a decline in CrCl and lowered levels of endogenous digitalis-like factor (EDLF) activity as measured by sodium pump inhibition (SPI). However, some PE subjects had undetectable EDLF. The hypothesis tested was that only PE women with measureable EDLF would respond to DIF treatment and analysis of EDLF positive women might reveal treatment effects masked by inclusion of EDLF negative, and hence non-responding, PE women. Accordingly, analyses of DIF effects in EDLF positive PE women were conducted. Patient characteristics and study design have been published (1). In these subanalyses, subjects were considered to be EDLF positive if their plasma inhibited red cell sodium pump mediated Rb uptake. All analyses were redone for the EDLF positive subgroup by Covance Inc as in the original trial. Continuous data were analyzed by ANCOVA. Categorical data were analyzed by Barnard Exact Test. 45 subjects (23 DIF, 22 placebo) had baseline SPI evaluated. Of these 22% had undetectable SPI. EDLF positive PE women showed greater and more significant reductions of SPI in response to DIF at each time point (12, 24, 48 hr treatment) than in the original analysis. Subjects with undetectable EDLF showed no significant change in response to DIF or placebo. For CrCl, EDLF positive PE women showed greater and more significant preservation of CrCl compared with original analyses. Subjects absent EDLF showed deterioration of CrCl with or without DIF. Among EDLF positive PE women DIF treated women had significantly less maternal pulmonary edema (p=0.035) and significantly less intraventricular hemorrhage in their infants (p=0.015). There was the suggestion of reductions in the incidence of other maternal and neonatal abnormalities. These data indicate that EDLF positive PE women are those that responded to DIF and also raise the possibility of extended benefits of DIF treatment in this group. Results support further research in this area.

Two-dimensional, sex-specific autosomal linkage scan of the number of sodium pump sites

The sodium pump consists of the membrane-bound enzyme sodium/potassium-ATPase, which exchanges internal sodium ions for external potassium ions. Obesity, hypertension, and diabetes associate with the activity of the sodium pump, motivating gene discovery for sodium pump number. Variance components linkage analysis was applied to the number of red blood cell sodium pump sites measured by ouabain-binding assays on 1375 members of 46 Utah pedigrees. Both one-dimensional (1D) and two-dimensional (2D) autosome-wide linkage analyses of pump number were performed on the combined sample as well as separately on the male and female subsets. Two significant 1D linkages were identified: on chromosome 1p13 in the combined sample [1D logarithm of odds (LOD) score = 3.76] and on chromosome 17p21 in the female subset (1D LOD score = 3.24). In addition, two significant 2D linkages were identified in the female subset: on chromosome 10q22 interacting with chromosome 18q11 (2D LOD score = 7.18) and on chromosome 13q21 interacting with chromosome 4q31 (2D LOD score = 6.05). Single-nucleotide polymorphism rs17376826 in neuropeptide Y receptor Y2, an obesity-associated gene and a candidate in the chromosome 4q31 linkage region, is associated with pump number (P = 0.046 in the combined sample and P = 0.042 in the female subset). Pump number is influenced by multiple genes, possibly including neuropeptide Y receptor Y2.

Effects of hormone replacement therapy with vitamin C and E supplementation on plasma thyroid hormone levels in postmenopausal women with Type 2 diabetes

Recent studies have shown that hormone replacement therapy (HRT) can exert regulatory affects on lipid and glucose homeostasis. It has been demonstrated that hyperglycemia also involving the formation of lipid peroxides, exert several biological effects that may contribute to the onset and progression of thyroid and kidney abnormalities of postmenopausal women Type 2 diabetes. Therefore, the aim of our study was to evaluate the effect of HRT, vitamin C and E (VCE) treatments on some plasma biochemical and hematological parameters and plasma thyroid hormone levels in postmenopausal women with or without diabetes. Oral HRT and VCE supplementation were compared with no HRT treatment in 40 non-diabetic postmenopausal women and 40 postmenopausal women with Type 2 diabetes mellitus, in a 6-week randomized prospective study. In the 20 women with diabetes who received oral HRT and the 20 women with diabetes who received HRT plus VCE, there was a significant fall in urea, uric acid, creatinine, total bilirubin, conjugated bilirubin, AST, ALT, LDH values. There was no significant change in red blood cell counts, total protein, albumin, sodium, potassium, hematocrit, hemoglobin and free thyrotoxine and triiodothyronine values in postmenopausal women with diabetes or treated with oral HRT and VCE. In conclusion, daily VCE and HRT administrations seem to produce significant improvement on biochemical parameters in the blood of postmenopausal women with Type 2 diabetes. The HRT and VCE supplementations may strengthen the antioxidant defense system and they may play a role in preventing kidney and liver diseases of postmenopausal women with Type 2 diabetes.

Magnesium status and dietary intake of mid-old people in a rural area of China

To evaluate the status and dietary intake of magnesium in mid-old people in a rural area of China, a total of 324 mid-old people (111 males and 213 females) aged 55-70 were randomly selected. All the subjects were divided into four groups: a normal group (N), a hypertension group (H), an impaired fasting glucose group (IFG) and a diabetic group (D). Magnesium, sodium, potassium, calcium, iron, zinc, and copper concentrations in red blood cells (RBC) were measured by emission spectroscopy (ICP-OES), and dietary intakes were surveyed by 24-hr recall questionnaires. The data were analyzed between groups and also between genders. The average body weight and BMI were 59.4 kg and 22.1 in subjects with IFG, and 62.4 kg and 23.5 in the diabetics, which were higher than those of the normal group (p < 0.05 and p < 0.01). The average magnesium concentration in RBC was significantly lower in the hypertension group than in the normal group (2.0 mmol/L vs. 2.2 mmol/L, p < 0.05). Groups H, IFG and D took less magnesium than group N (315.9 mg/d, 331.6 mg/d and 323.3 mg/d vs. 371.54 mg/d, p < 0.05). Women took less magnesium than men (326.2 mg/d vs. 373.7 mg/d, p < 0.05). There were no significant differences in other mineral concentrations in RBC and dietary intakes. Results of this study show that magnesium concentration in RBC is lower in mid-old people suffering hypertension as compared to healthy subjects. Dietary intakes of magnesium are lower in mid-old people suffering hypertension, IFG and diabetes as compared to healthy subjects. This indicates that an increase in the magnesium supply would be beneficial to mid-old people.

Cations Content And Membrane Properties Of Human Sickle Blood Incubated With Hydroxyurea, Tellurite And Thiocyanate

The effect of hydroxyurea, sodium thiocyanate and potassium tellurite on cations content and membrane properties of sickle erythrocyte was investigated in this study. Human sickle blood was incubated with the drugs in vitro at their optimum sickling inhibitory concentration. Mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC), cations (Na+, K+ and Ca2+) contents and viscosity were measured. Tellurite and thiocyanate significantly increased (P&#61500;0.05) MCV, reduced MCHC and blood viscosity and also significantly inhibited (P&#61500;0.05) calcium accumulation by sickle red blood cell. In addition, the two drugs increased red blood cell sodium gain and inhibited potassium loss significantly. Incubation of the drugs with sickle erythrocyte ghost membrane indicated that tellurite and thiocyanate significantly inhibited (P&#61500;0.05) Na+-K+-ATPase (EC 3.6.3.9) and Ca2+-Mg2+-ATPase (EC 3.6.3.8) activities. Blood incubated with hydroxyurea also significantly inhibited (P&#61500;0.05) calcium ion accumulation but had no effect on all other measured parameters. This result suggests that thiocyanate and tellurite have positive modification effect on sickle erythrocyte membrane and cation transport thereby causing rehydration and improvement in red blood cell deformability. Keywords: Cations content, Erythrocyte Membrane, Hydroxyurea, Sodium thiocyanate, Potassium tellurite Egyptian Journal of Biochemistry and Molecular Biology Vol. 26 (1) 2008 pp. 117-125

More on the sodium saga.

The relationship between sodium (salt) intake and blood pressure has been convincingly established by epidemiological, observational, interventional, physiological, and some genetic evidence for some time. Yet the interaction remains the subject of passionate and heated debate. Even among those who are convinced of the salt–blood pressure interaction, some advocate a population-wide attempt to reduce dietary salt intake, arguing on the basis of epidemiological and interventional evidence, and others who suggest that such interventions should be targeted toward those most likely to benefit: the “salt-sensitive” subpopulation. Studies have characterized such subgroups on the basis of higher blood pressure, increased age or African-American ethnicity.1 The issue is rendered even more compelling by the findings that salt sensitivity can be identified among “normotensive” subjects (ie, those with blood pressure <140/90) as well as those with hypertension1 and the designation of those with blood pressure levels between 120 and 139 mm Hg systolic and 80 and 89 diastolic as prehypertensive2 and at increased risk for development of fixed hypertension and for cardiovascular events compared with those with lower blood pressure.3 Observational data have provided a starting point for the quantitative considerations of dietary salt intake. The most recent (1999–2000) NHANES survey provides an estimated dietary sodium intake based on food records, excluding discretionary sodium, of 135 to 204 mmol per day for men and 100 to 135 mmol per day for women in the United States.4 Questionnaires are acknowledged to underestimate actual intake, and urinary sodium excretion has been shown to provide a more accurate index of total sodium intake because it represents ≈93% of intake at steady-state conditions.5 A recent British survey reported that urinary sodium excretion averaged 187 mmol per day for men and 139 mmol per day for women.5 This was very similar to …

A stomatin and a degenerin interact in lipid rafts of the nervous system of Caenorhabditis elegans.

In Caenorhabditis elegans, the gene unc-1 controls anesthetic sensitivity and normal locomotion. The protein UNC-1 is a close homolog of the mammalian protein stomatin and is expressed primarily in the nervous system. Genetic studies in C. elegans have shown that the UNC-1 protein interacts with a sodium channel subunit, UNC-8. In humans, absence of stomatin is associated with abnormal sodium and potassium levels in red blood cells. Stomatin also has been postulated to participate in the formation of lipid rafts, which are membrane microdomains associated with protein complexes, cholesterol, and sphingolipids. In this study, we isolated a low-density, detergent-resistant fraction from cell membranes of C. elegans. This fraction contains cholesterol, sphingolipids, and protein consistent with their identification as lipid rafts. We then probed Western blots of protein from the rafts and found that the UNC-1 protein is almost totally restricted to this fraction. The UNC-8 protein is also found in rafts and coimmunoprecipitates UNC-1. A second stomatin-like protein, UNC-24, also affects anesthetic sensitivity, is found in lipid rafts, and regulates UNC-1 distribution. Mutations in the unc-24 gene alter the distribution of UNC-1 in lipid rafts. Each of these mutations alters anesthetic sensitivity in C. elegans. Because lipid rafts contain many of the putative targets of volatile anesthetics, they may represent a novel class of targets for volatile anesthetics.

Mechanism underlying the strong positive inotropic effects of LND-623: specific inhibition of Na, K-ATPase isoforms and exclusion of cellular sites of contractile control.

LND-623 is a new aminosteroid analog of ouabain, with a greater separation between efficacy and toxicity than ouabain. To determine its mechanism of action, we studied its biochemical and physiological effects on human red blood cell sodium transports on different cellular structures regarded as sites of contractile control, and we compared its relative efficacy to ouabain in rat heart preparations and membrane-bound Na, K-ATPase isoenzymes. The response to ouabain was evaluated in Langendorff-perfused hearts and on purified membrane-bound Na, K-ATPase. LND-623 is 6.8-fold more efficient than ouabain in inhibiting the human Na+ pump (IC50 = 0.098 +/- 0.001 microM vs. 0.67 +/- 0.02 microM); (P < 0.0001). LND-623 had no effect on the following cellular functions: Na-Ca exchange, Na-K cotransport, Ca-ATPase, slow calcium channels, adenylate cyclase system, phosphodiesterase, and calcium sensitivity of the contractile protein system. The dose-response curve for the positive inotropic and inhibitory effects on rat cardiac isoenzymes produced by LND-623 were clearly biphasic. The amplitude of the maximum inotropic effect, without any toxic effect, was up to three-fold higher with LND-623 than with the same maximum dose of ouabain used. The strong positive inotropic effect of LND-623 in rats could be related to a specific inhibition of the two rat cardiac isoforms of the Na, K-ATPase.

Sodium lithium countertransport and blood pressure. Longitudinal findings.

A significant and positive association between red blood cell sodium lithium countertransport (Na-Li CT) and blood pressure has been found in numerous studies. However, the majority of the studies presented to date are cross-sectional in nature and limited information exists on the longitudinal association between Na-Li CT and blood pressure. The present study analyzes the longitudinal association between Na-Li CT and blood pressure in 124 men participants in the Olivetti Heart Study and normotensives at the baseline examination. The Na-Li CT measured at the 12 year follow-up examination was analyzed in regard to the blood pressure changes over time during the 12 year follow-up. Na-Li CT (measured at follow-up examination) was positively related to changes over time in systolic pressure (r = 0.16) and diastolic pressure (r = 0.07) and changes in body mass index (r = 0.18). When blood pressure changes over time were analyzed by tertiles of Na-Li CT, the highest tertile group exhibited on the average significantly higher increases in systolic blood pressure compared with participants of the lowest tertile of the Na-Li CT distribution. This difference remained statistically significant after adjusting for the changes in weight observed during the 12 years follow-up. These findings indicate that the Na-Li CT distribution is related to blood pressure changes over time. However, the usefulness of Na-Li CT as a predictor of incidence of hypertension remains to be established.

Finoptin effect on electrolyte metabolism of diabetics with essential hypertension

It is universally acknowledged that some hypotensive agents may have a negative impact on electrolyte metabolism. This study was aimed at investigating the baseline status of electrolyte metabolism in patients with types I and II diabetes and concomitant essential hypertension and at following up the changes in this parameter over the course of verapamil (finoptin) therapy. Fifty-six patients were followed up. Levels of potassium and sodium in the plasma and red cells, total and ionized calcium in the plasma were measured before therapy and after 0.5, 1.5, and 6 months of finoptin therapy. Higher levels of plasma potassium and red cell sodium were revealed in patients with type I diabetes in comparison with those with type II condition. In patients with noninsulin-dependent diabetes potassium concentrations in red cells and ionized calcium in the plasma were higher. Finoptin therapy promoted a decrease of sodium concentration in the red cells in diabetics with both types I and II condition and a reduction of the level of ionized calcium in the plasma of patients with type II diabetes. Changes in the electrolyte metabolism were transitory and do not require special laboratory monitoring.

A23Na Multiple-Quantum-Filtered NMR Study of the Effect of the Cytoskeleton Conformation on the Anisotropic Motion of Sodium Ions in Red Blood Cells

Recently, it has been shown that23Na double-quantum-filtered NMR spectroscopy can be used to detect anisotropic motion of bound sodium ions in biological systems. The technique is based on the formation of the second-rank tensor when the quadrupolar interaction is not averaged to zero. Using this method, anisotropic motion of bound sodium in human and dog red blood cells was detected, and the effect was shown to depend on the integrity of the membrane cytoskeleton. In the present study, multiple-quantum-filtered techniques were applied in combination with a quadrupolar echo to measure the transverse-relaxation times,T2fandT2s. Line fitting was performed to obtain the values of the residual quadrupolar interaction, which was measured for sodium in a variety of mammalian erythrocytes of different size, shape, rheological properties, and sodium concentrations. Human unsealed white ghosts were used to study sodium bound at the anisotropic sites on the inner side of the RBC membrane. Modulations of the conformation of the cytoskeleton by the variation of either the ionic strength or pH of the suspending medium caused drastic changes in both the residual quadrupolar interaction andT2fdue to changes in the fraction of bound sodium ions as well as changes in the structure of the binding sites. By combining the two spectroscopic parameters, structural change can be followed. The changes in the structure of the sodium anisotropic binding sites deduced by this method were found to correlate with known conformational changes of the membrane cytoskeleton. Variations of the medium pH affected both the fraction of bound sodium ions and the structure of the anisotropic binding sites. Sodium and potassium were shown to bind to the anisotropic binding sites with the same affinity.

Increased Cation Permeability in Mutant Mouse Red Blood Cells With Defective Membrane Skeletons

Cellular cation homeostasis in mouse erythrocytes with defective membrane skeletons was examined in three mouse mutants, hemolytic anemia (sphha/sphha), spherocytosis (sph/sph), and normoblastosis (nb/nb), and compared with reticulocytes produced by repetitive bleeding of congenic normal mice. To assess reticulocyte maturity, nucleic acid and transferrin receptor contents were measured by fluorescence flow cytometry; mutant cells were somewhat more mature than normal reticulocytes by these criteria. Red blood cell (RBC) sodium contents (Nac+) in homozygous sphha/sphha, sph/sph, and nb/nb animals were 30.1 +/- 0.9, 28.9 +/- 0.3, and 26.9 +/- 1.5 mmol/L cell, respectively, whereas cellular potassium (Kc+) was 102 +/- 2.6, 101 +/- 7.8, and 97.4 +/- 3.0. Nac+ and Kc+ in normal reticulocyte preparations were 11.3 +/- 0.7 and 123 +/- 10, respectively. Net Na+ and K+ fluxes in the presence of ouabain were markedly increased in mutant RBCs. Sodium uptake was 14.8 +/- 1.6, 15.4 +/- 3.3, and 14.7 +/- 3.1 mmol/L cell/h in sphha/sphha, sph/sph, and nb/nb mutants, respectively, whereas K+ loss was 17.0 +/- 4.0, 15.0 +/- 3.8, and 14.1 +/- 2.6. Normal mouse reticulocytes gained Na+ at a rate of 3.9 +/- 1.0 mmol/L cell/h and lost K+ at 6.0 +/- 2.1, rates indistinguishable from those in mature mouse RBCs. Potassium loss from sphha/sphha and nb/nb cells was not dependent on the presence of a Na+ gradient, and net cation movements were insensitive to bumetanide (sphha/sphha and nb/nb RBCs) and to chloride replacement with sulfamate (nb/nb cells). We conclude that mutant mouse RBCs with dysfunctional membrane skeletons have increased passive permeability to monovalent cations. These findings support a role of the membrane skeleton in the maintenance of the membrane permeability barrier and suggest that the abnormal permeability associated with human hereditary spherocytosis and elliptocytosis may be a consequence of the membrane skeleton defects reported in these disorders.

Calcium Supplementation Attenuates an Enhanced Platelet Function in Salt-Loaded Mildly Hypertensive Patients

We designed this study to evaluate the effect of low versus high calcium intake on platelet function in salt-loaded patients with mild hypertension. After a 7-day period of dietary salt restriction, 19 patients were placed on a high salt (300 mmol/d), low calcium (6.25 mmol/d) diet for 7 days; 10 of these patients were given 54 mmol/d of supplementary calcium, and 9 patients were given placebo. At the end of the low and high salt regimens, we evaluated changes in blood pressure, platelet aggregation, and the platelet release reaction measured as plasma beta-thromboglobulin and platelet factor 4 levels. With high salt intake, significant increases in mean blood pressure (P < .02), red blood cell sodium (P < .01), and platelet aggregation induced by 3 mumol/L ADP (P < .01) and by 3.0 mg/L epinephrine (P < .05) were observed in the placebo-treated patients but not in the calcium-supplemented ones. Compared with the placebo-treated patients, calcium-supplemented patients had a smaller weight gain (P < .05) but excreted more sodium and calcium (P < .01) at the end of the high salt regimen. Calcium supplementation resulted in decreases in beta-thromboglobulin (P < .05), platelet factor 4 (P < .01), and plasma and urinary excretions of norepinephrine (P < .02) during the high salt, low calcium regimen. The decrease in plasma norepinephrine correlated positively with the decreases in beta-thromboglobulin (r = .72, P < .02) and platelet factor 4 (r = .85, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of long-term antihypertensive therapy with angiotensin converting enzyme inhibitors on red cell sodium transport

Several sodium transport abnormalities have been reported in erythrocytes from essential hypertensive patients. The possible modification of these parameters under antihypertensive treatment remains controversial. We have measured the maximal rates of the Na+/K+ pump, Na+/K+/Cl- cotransport, and Na+/Li+ countertransport and the rate constant of Na+ leak in erythrocytes from 22 essential hypertensive patient responders to angiotensin converting enzyme inhibitors quinapril or captopril, and from 17 patient nonresponders to these drugs. In the former group, sodium transport measurements were performed at the baseline placebo period and after 6 months of active treatment. The maximal rate of Na+/Li+ countertransport decreased significantly after 6 months of treatment, without differences between both groups of treatment. Angiotensin converting enzyme inhibitors did not significantly modify other sodium transport parameters. The basal activity of erythrocyte sodium transport was not different between patients who responded or not to antihypertensive treatment with those drugs, excluding a predictive value of these measurements concerning the response to angiotensin converting enzyme inhibitors.

Red blood cell sodium and potassium concentration and blood pressure: The Gubbio Population Study

The relations of red blood cell sodium (RBC Na) and potassium (RBC K) concentrations to blood pressure and prevalence of hypertension were assessed for 1805 men and women, aged 25 to 74 years, who participated in the baseline examination of the Gubbio Population Study in north central Italy. In men, in univariate analyses, RBC Na concentration was not significantly related to systolic or diastolic blood pressure, while RBC K concentration was significantly and inversely related to blood pressure. In women RBC Na values correlated significantly and directly with systolic and diastolic pressure, but RBC K concentration was not significantly related to blood pressure. Results of the multivariate analyses indicated in men a significant independent and inverse relationship of RBC K concentration with hypertension and blood pressure, and in women a significant positive association of RBC Na concentration with hypertension. RBC Na did not relate independently to either systolic or diastolic blood pressure in men or women. Age-specific analyses suggested that the relationships between RBC K level and blood pressure in men and the relationship between RBC Na level and hypertension in women were stronger in older (age 55 to 74 years) compared to younger participants (25 to 54 years). These findings indicate that the associations of RBC Na and K concentrations and hypertension may be sex and age specific. The nature of these gender- and age-specific associations remains to be clarified. Prospective data are also needed for further clarification of the relation of intracellular Na metabolism to the etiology of hypertension.

Red blood cell sodium content in NID diabetic patients with hemorheological abnormalities

Red blood cell sodium content in NID diabetic patients with hemorheological abnormalities

CATECHOLAMINE-ACTIVATED SODIUM/PROTON EXCHANGE IN THE RED BLOOD CELLS OF THE MARINE TELEOST GADUS MORHUA

The effects of catecholamines on the pH and the cellular ion and water content were investigated in red blood cells from the Atlantic cod (Gadus morhua). Noradrenaline induced a rapid decrease in the extracellular pH (pHe) of red blood cells suspended in a CO2/bicarbonate or in a CO2/bicarbonate-free buffer system. The noradrenaline-induced changes in pHe were a saturable function of the external sodium ion concentration and were inhibited by amiloride but not by DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid, final concentration of both 10(-4) mol l-1). The catecholamine-induced extracellular acidification was accompanied by an intracellular alkalization and protons were moved from their electrochemical equilibrium. Proton extrusion was associated with an increase in the red blood cell sodium and chloride concentrations. In the presence of DIDS, the chloride movements were blocked and the net proton efflux under these conditions matched the net sodium influx. The results strongly suggested the activation of a sodium/proton exchanger by catecholamines in the red blood cells of the Atlantic cod. The red blood cell receptor affinity for adrenaline was three times higher than that for noradrenaline. Comparison with data in the literature for in vivo catecholamine concentrations indicated that adrenaline was more effective than noradrenaline in activating the red blood cell sodium/proton exchanger in the Atlantic cod in vivo.

Alteration in Red Blood Cell Sodium and Potassium Concentrations and Increased Lipid Peroxidation in Patients with Chronic Renal Failure on Maintenance Hemodialysis: A Hypothesis

Alteration in Red Blood Cell Sodium and Potassium Concentrations and Increased Lipid Peroxidation in Patients with Chronic Renal Failure on Maintenance Hemodialysis: A Hypothesis

Increased Red Cell Sodium Lithium Countertransport Activity, Total Exchangeable Sodium, and Hormonal Control of Sodium Balance in Normoalbuminuric Type 1 Diabetes

The relationship between erythrocyte sodium lithium countertransport activity (SLC), total exchangeable sodium (NaE), and hormonal control of renal function was examined in 40 normotensive, normoalbuminuric, non-neuropathic Type 1 diabetic subjects, of whom 8 had elevated SLC (> 0.40 mmol Li h-1l-1 rbc). Eleven health controls with normal SLC, who were of comparable age, body mass, and blood pressure were also studied. By contrast with healthy controls, SLC in Type 1 diabetes was not associated with plasma renin activity (PRA), aldosterone, systolic blood pressure or lean body mass. SLC was also unrelated to atrial natriuretic peptide (ANP) (Type 1 diabetes only) and NaE. NaE was not correlated with any other variables. The relationships between PRA and aldosterone in healthy controls were retained in Type 1 diabetes (R2 0.37 supine, p = 0.00001, and 0.27 ambulant, p = 0.0005), as were respective direct and inverse relations between vasopressin and ANP and both PRA (rs 0.54 to 0.57, rs -0.43 to -0.53), and aldosterone (rs 0.78 to 0.80, rs -0.71 to -0.80). Fasting free serum insulin and vasopressin were both inversely related to ANP (rs -0.91 and -0.71, respectively). In the absence of autonomic dysfunction, hypertension or early nephropathy in Type 1 diabetes, increased SLC or exchangeable sodium were unrelated to each other or with hormonal control of sodium balance, but the homeostatic factors controlling hormonal interaction appear to be maintained. The interaction between insulin and hormonal control of sodium and water balance may be modified by circulating free insulin concentrations.