Intraerythrocytic Concentration Research Articles

Suppressive Effect of Sulfate on the Development of Hypertension in DOCA-Salt Hypertensive Rats

The purpose of this study was to examine the effect of the sulfate ion on blood pressure in DOCA-salt hypertension, which involves increased sympathetic nervous activity. Male Wistar rats were divided into four groups, and received one of the following drinking solutions: distilled water [control], 171 mmol/L sodium chloride [NaCl group], 171 mmol/L sodium chloride plus 12 mmol/L magnesium sulfate [S(+) group], or 171 mmol/L sodium chloride plus 12 mmol/L magnesium chloride [S(-) group]. In the S(+) group, the elevation of systolic blood pressure (SBP; mm Hg) was significantly attenuated (168 +/- 17 v 213 +/- 26, P less than .005) and intraerythrocyte calcium concentration (R-Ca; mumol/L cells) was significantly lower (11.5 +/- 3.0 v 17.4 +/- 6.5, P less than .05) than in the S(-) group. The cardiac norepinephrine content (H-NE; ng/100 g tissue) of the S(+) group was significantly lower than that of the S(-) group. SBP was correlated negatively with H-NE (r = -0.70, P less than .001) and positively with R-Ca (r = 0.45, P less than .005). R-Ca was negatively correlated with H-NE (r = -0.36, P less than .05). These results suggest that the replacement of chloride with sulfate ion suppresses the development of hypertension in DOCA-salt rats at least in part by its inhibitory effect on sympathetic nervous activity through the decreased intracellular calcium concentration.

Erythrocyte sodium transport in malignant hypertension

Twenty-three patients with treated malignant hypertension (MH), 23 patients with treated non-malignant hypertension (NMH) and 46 normotensive control subjects were investigated with regard to intraerythrocyte sodium (Na) and potassium (K) levels, as well as transmembrane fluxes of sodium (Na-influx and Na-efflux rate constant). Intraerythrocyte Na and K concentrations were determined by flame photometry. The Na-influx and Na-efflux rate constant were calculated from uptake values for 22Na in vitro. In NMH the Na-influx and Na-efflux rate constant were significantly higher while intraerythrocyte Na and K levels did not differ from the controls. Patients with MH tended to have an elevated intraerythrocyte Na concentration, but an unchanged Na-influx and Na-efflux rate constant relative to controls. The increased rate of erythrocyte membrane transport of Na in treated NMH could be due to a stimulatory effect of antihypertensive treatment on cellular Na transport. Patients with treated MH do not show this effect, and in addition, tend to have an elevated intraerythrocyte Na concentration, which is compatible with the existence of a more pronounced abnormality of cellular ion transport in MH.

Erythrocyte concentrations and transmembrane fluxes of sodium and potassium in essential hypertension: Role of intrinsic and environmental factors

The intraerythrocyte sodium concentration is increased in the erythrocytes of Zaïrean Bantu with untreated hypertension, while the red blood cell potassium is not different from that of normotensive subjects. Compared with whites, normotensive healthy blacks have a higher intracellular concentration of sodium due to a depressed activity of the sodium-potassium pump. Normotensive healthy males with a positive familial background of hypertension display higher erythrocyte sodium and lower cotransport activity. None of the two measurements offer a clear-cut genetic marker of essential hypertension. In healthy women, the erythrocyte sodium concentration is lowered during the luteal as compared with the follicular phase of the menstrual cycle. This variability explains the difference observed between men and women. A low-sodium diet stimulates the activity of the sodium-potassium ATPase pump, which leads to a decrease in the erythrocyte sodium concentration. Both alterations reverse only slowly during sodium repletion. It is therefore suggested that an adequate matching for race, sex, stage of the menstrual cycle (in women), family history of hypertension, and the amount of sodium in the diet should be a prerequisite for valid conclusions when interpreting the erythrocyte concentration and fluxes of sodium.

Effects of Ketanserin on Transmembrane Sodium Transport in Erythrocytes

Ketanserin, an antagonist of 5-HT2-serotonergic and alpha 1-adrenergic receptors, has come into use for the therapy of mild to moderate arterial hypertension. Quite recent observations have shown changes in transmembrane sodium (Na) transport after the acute administration of high doses of this drug to normal subjects. It is well known that some of these transport systems have an altered activity in essential hypertension. We evaluated the effects of long-term (3 months) administration of ketanserin (40-80 mg/day) on Na and potassium (K) intracellular concentrations and transmembrane fluxes in red blood cells (RBCs) from 12 essential hypertensive patients. In addition the present study describes the in vitro effects of two different concentrations of the drug (5 x 10(-8) and 5 x 10(-7) M) on erythrocytes in normal subjects. In the first study, both systolic and diastolic blood pressure were significantly lowered by the treatment with ketanserin (from 165/103 to 143/89; p less than 0.001). Na and K intraerythrocyte concentrations fell markedly during ketanserin administration (both p less than 0.001). A marked decrease in Na,K-pump activity (p less than 0.001) and an increase in Na,lithium(Li)-countertransport function (p less than 0.001) were observed. Na outward cotransport, Na leak, and K leak were not modified by the therapy. Direct correlation was found between the fall in mean blood pressure and in Na and K intraerythrocyte concentration (respectively, p less than 0.01 and p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of calcium and erythrocyte cytoskeleton phosphorylation in the invasion ofPlasmodium falciparum

The role of calcium in the invasion of the human erythrocyte by the parasite Plasmodium falciparum was studied. The intraerythrocytic and intraparasitic concentrations of Ca2+ were modified using calcium-ionophore A23187 and the chelator EGTA. The Ca2+ inside the parasite appeared to be necessary for the normal completion of invasion. We determined that in recently invaded erythrocytes (2 h), the Ca2+ concentration increased about 10 times. Merozoite invasion produced a decrease in beta-spectrin phosphorylation and an increase in the phosphorylation of a protein with band 4.1 mobility. These changes were similar to those produced by an ionophore-mediated Ca2+ influx in uninfected erythrocytes. These facts support the idea that a calcium influx into erythrocytes might precede or accompany merozoite invasion, triggering a series of molecular events, including phosphorylation and dephosphorylation of cystoskeletal proteins.

Effect of alcohol ingestion on urinary excretion and intraerythrocyte concentrations of sodium and potassium.

Although epidemiologic studies have demonstrated that alcohol consumption is related to increased blood pressure, the mechanism involved has not been fully understood. In the present study the urinary excretion and intraerythrocyte concentrations of sodium and potassium after alcohol ingestion were measured in 7 young adults. Decreases of urinary excretion of sodium and potassium and an increase in intraerythrocyte sodium were observed. The results suggest that alterations of the electrolyte metabolism influenced by alcohol ingestion may be related to alcohol-induced hypertension.

Measurement of cation transport in vivo in healthy volunteers after the oral administration of lithium carbonate

1. We have measured cation transport in vivo in seven healthy volunteers under control conditions and after they had taken lithium carbonate for 21 days in doses which maintained the serum lithium concentration in the range 0.6-0.8 mmol/l. 2. We have measured cation transport in vivo after the administration of an oral load of rubidium chloride, and have found that, although intra-erythrocytic concentrations of rubidium were significantly lower 1 h after the administration of rubidium when the subjects were taking lithium, there was a significant increase in the rate of uptake of rubidium into the erythrocytes over the subsequent period of the test, suggesting a direct stimulation of sodium, potassium-activated adenosine triphosphatase by lithium. 3. Lithium administration did not affect the plasma concentration versus time profile of rubidium after the rubidium load, implying that the lithium-stimulated uptake of rubidium which occurs in erythrocytes does not necessarily occur in other cell types. 4. These results suggest that previous studies of cation transport using peripheral cells and assay systems in vitro do not necessarily reflect changes in cation transport in vivo in excitable tissues.

The interaction of alpha-thalassemia with sickle cell anemia.

The coinheritance of alpha-thalassemia (alpha-thal) and sickle cell anemia provides a most interesting example of how separate globin gene mutations influence clinical manifestations of abnormal gene expression. Early reports in the literature contained conflicting opinions as to whether alpha-thal ameliorated the clinical consequences of sickle cell disease. With the discovery that the concentration of sickle hemoglobin (Hb S) had a profound influence on both the kinetics and extent of deoxy Hb S polymerization, it was predicted that the lower intraerythrocytic concentration of Hb S associated with alpha-thal would mitigate the clinical severity of sickle cell anemia. Moreover, the use of alpha-globin gene mapping for objectively diagnosing alpha-thal revealed that one in three Black Americans were silent carriers of alpha-thal. Thus, it followed that a great many sickle cell patients may be affected by this potentially modifying influence.

31P nuclear magnetic resonance study of variations in intra-erythrocytic ATP concentration and pH induced by surgical trauma.

Variations in intracellular pH and ATP concentrations in erythrocytes were studied in patients undergoing a mild surgical intervention. Intra-erythrocytic pH was decreased at the end of the operation; ATP concentrations concomitantly increased, but not highly significantly. These variables returned to their initial values by 20 h after the end of surgery.

Assay of sodium-lithium countertransport rate by direct measurement of erythrocyte lithium concentrations

A method is described for the in-vitro measurement of erythrocytic sodium-lithium countertransport rate (SLC) by direct assay of intra-erythrocytic lithium (Li) concentrations in Li loaded cells during controlled Li efflux. Bicarbonate stimulated erythrocytic Li loading to an approximate intracellular concentration of 3 mmol/l can be achieved within 4 min. Maximum SLC rates are achieved at intra-erythrocytic concentrations greater than 2.5 mmol/l. Lithium efflux is linear over 0–60 min, and independent of pH change. The within-batch coefficient of variation for positive displacement pipetting of Li loaded erythrocytes is 2.8%. Storage of erythrocytes in isosmotic MgC1 2 for 24 h had no effect on the SLC. Intra-individual coefficient of variation for SLC was less than 6%. The reference range for Caucasian subjects ( n = 43) was 0.14–0.49 mmol Li + /l erythrocytes/h.

Influence of magnesium on blood pressure and the effect of nifedipine in rats.

The influence of long-term alterations in dietary magnesium intake on blood pressure and on the antihypertensive effect of the calcium antagonist nifedipine was investigated in normotensive Wistar-Kyoto (WKY) and in spontaneously hypertensive rats (SHR). The rats were fed a diet either high (1%), normal (0.1%), or low (0.01%) in magnesium for 12 weeks (WKY) and 20 weeks (SHR), respectively. Nifedipine was added to the diet for 4 weeks in concentrations of 300 and 1000 ppm. Each dose was given for 2 weeks. Plasma and intraerythrocytic concentrations of sodium, potassium, and magnesium were measured before and at the end of nifedipine treatment. Blood was obtained by cardiac puncture. In the WKY and SHR, blood pressure was not influenced by magnesium intake. The blood pressure-lowering effect of nifedipine was most pronounced on normal dietary magnesium and was significantly suppressed in the magnesium-deficient rats. Plasma and intracellular total magnesium concentrations were consistently increased during high and reduced during low dietary intake of the ion. Intracellular sodium concentration increased during magnesium deficiency and was normalized by nifedipine. The marked and long-term alterations in plasma and intracellular concentrations of magnesium did not influence arterial blood pressure levels in either the normotensive WKY or the SHR. Therefore, dietary magnesium intake does not appear to play an important role in long-term regulation of blood pressure in rats. However, magnesium depletion attenuates the blood pressure-lowering effect of nifedipine.

Cationic concentrations and transmembrane fluxes in erythrocytes of humans during exercise.

The effect of exercise on the intraerythrocyte cationic concentrations and transmembrane fluxes such as the Na+-K+-adenosinetriphosphatase (ATPase) pump, the Na+-K+ cotransport, and the Na+-Li+ countertransport system was studied in 11 normal male volunteers. All subjects performed an uninterrupted incremental exercise test on a bicycle ergometer, starting at an initial work load of 20% of the subjects' maximal exercise capacity, as determined in a pretest. The work rate was increased with an additional 20% each 6 min up to a final work load of 80%. Blood samples were taken at rest, at 60 and 80% of maximal exercise capacity, and 1, 2, 3, 4, 5, and 30 min after cessation of exercise. At moderate exercise (60% of maximal exercise capacity) the intraerythrocyte potassium concentration was not changed, but at severe exercise (80% of maximal exercise capacity) it was decreased. After exercise the intraerythrocyte potassium concentration returned to base line within 2 min. Exercise did not affect the intraerythrocyte concentrations of sodium and magnesium. The activity of the Na+-K+-ATPase pump and the Na+-K+ cotransport in the erythrocytes during and after exercise was no different from the resting level. The activity of the Na+-Li+ countertransport system on the contrary tended to decrease during exercise. It is concluded that exercise is accompanied by a leakage of potassium out of the erythrocytes without major alterations in the active red cell cationic fluxes.

Cation transport abnormalities in vivo in untreated essential hypertension.

In order to study cation transport in vivo we have measured the changes in plasma and intra-erythrocytic rubidium concentrations after the oral administration of rubidium chloride. In this paper we describe our findings in 22 patients with untreated essential hypertension, compared with the findings in 22 carefully matched control subjects. Our findings in patients receiving short-term digoxin therapy and in patients with chronic renal failure are also included for comparison. Whereas the findings in patients receiving digoxin and in patients with chronic renal failure are compatible with a widespread reduction in sodium, potassium-ATPase activity in vivo, the findings in patients with untreated essential hypertension are not. Further analysis of the data and a similar study of the disposition of 42K after the intravenous administration of 42KCl suggest that in vivo net cation transport is enhanced in the erythrocytes of patients with untreated essential hypertension.

Intraerythrocyte and plasma lactate concentrations during exercise in humans.

The purpose of this study was to examine plasma and intraerythrocyte lactate concentrations during graded exercise in humans. Seven adult volunteers performed a maximum O2 uptake (VO2max) test on a cycle ergometer. Plasma and intraerythrocyte lactate concentrations (mmol . L-1 of plasma or cell water) were determined at rest, during exercise, and at 15-min post-exercise. The results show that plasma and intraerythrocyte lactate concentrations were not significantly different from each other at rest or moderate (less than or equal to 50% VO2max) exercise. However, the plasma concentrations were significantly increased over the intraerythrocyte levels at 75% and 100% VO2max. The plasma to red cell lactate gradient reached a mean (+/- SE) 1.7 +/- 0.4 mmol . L-1 of H2O at exhaustion, and was linearly (r = 0.84) related to the plasma lactate concentration during exercise. Interestingly, at 15-min post-exercise the direction of the lactate gradient was reversed, with the mean intraerythrocyte concentration now being significantly increased over that found in the plasma. These results suggest that the erythrocyte membrane provides a barrier to the flux of lactate between plasma and red cells during rapidly changing blood lactate levels. Furthermore, these data add to the growing body of research that indicates that lactate is not evenly distributed in the various water compartments of the body during non-steady state exercise.

Erythrocyte cations and Na+,K+-ATPase pump activity in athletes and sedentary subjects

The chronic effect of training on intraerythrocyte cationic concentrations and on red cell Na+,K+-ATPase pump activity was studied by comparing well-trained athletes with sedentary subjects at rest. Also the acute effect of a 50-min cross-country run on these erythrocyte measurements was studied in the athletes. At rest the intraerythrocyte potassium concentration was increased (P less than 0.01) in the athletes compared to that of the control subjects. The intraerythrocyte concentrations of sodium and magnesium and red cell Na+,K+-ATPase pump activity were, however, similar in the trained and the untrained subjects. As compared with the resting condition, the intraerythrocyte potassium concentration was decreased (P less than 0.05) after exercise in the athletes, and this was accompanied by a minor increase in the intraerythrocyte sodium concentration. Red cell Na+,K+-ATPase pump activity was slightly increased (P less than 0.05) after exercise.

Intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of normal men and women

The intracellular concentration and transmembrane fluxes of sodium and potassium were studied in the red blood cells of normal men and women in the two halves of their menstrual cycle. Compared to men, the intra-erythrocyte sodium concentration was lower in women during the second half of the menstrual cycle. These two groups were similar for Na+, K+-ATPase pump activity estimated from the ouabain-sensitive 86rubidium-uptake and for the furosemide-sensitive sodium and potassium efflux. Women in the first half of the menstrual cycle, had intra-erythrocyte sodium concentration similar to men, but their furosemide-sensitive sodium efflux was lower. A lower intra-erythrocyte sodium concentration was observed in the second half as compared to the first half of the menstrual cycle in women. No significant difference was observed in the intra-erythrocyte potassium concentration and transmembrane fluxes of potassium in men and women in either half of the menstrual cycle. Therefore one should take into account sex-related variability when studying cationic fluxes and concentrations in red blood cells of men and women.

Effects of Ketanserin on the Intracellular Concentration and Transmembrane Fluxes of Sodium and Potassium in Erythrocytes of Normal Male Subjects

The effect of acute and short-term administration of ketanserin on the intracellular concentrations and transmembrane fluxes of sodium and potassium was studied in erythrocytes of 12 sodium-replete normal male subjects. The subjects received 40 mg ketanserin three times a day for 1 week. Blood samples were drawn before and 1.5 h after the first dose, 12 h after the evening dose of the 6th day, and 1.5 h after the morning dose of the 7th day. The intraerythrocyte sodium concentration was not changed after the first dose of ketanserin, but was decreased during short-term treatment with ketanserin. The ouabain-sensitive 86Rb-uptake, an estimate of the Na+,K+-adenosine triphosphatase pump activity, was decreased after acute ketanserin administration, but not during short-term treatment. This change in intraerythrocyte sodium concentration was related to the change in ouabain-sensitive 86Rb-uptake. The red cell Na+,K+-cotransport and Na+,Li+-countertransport transport activity were not changed during acute and short-term administration of ketanserin. These results indicate that short-term ketanserin administration decreases the intraerythrocyte sodium concentration, but the flux measurements can not explain this observation.

Hemolytic anemia in hereditary pyrimidine 5′-nucleotidase deficiency. II. Effect of pyrimidine nucleotides and their derivatives on glycolytic and pentose phosphate shunt enzyme activity

We evaluated the glycolytic intermediate concentrations from the erythrocytes of a patient with hereditary pyrimidine 5′-nucleotidase (P5′N) deficiency. Conclusive evidence for a metabolic block was not found. We evaluated the effects of the pyrimidine (cytidine and uridine) tri- and diphosphate nucleotides (CTP, CDP, UTP, UDP) and the choline and ethanolamine derivatives of CDP (CDP-choline, CDP-ethanolamine) on the activities of key enzymes of the Embden-Meyerhof pathway. CTP and UTP inhibited fructose-6-phosphate competitively for phosphofructokinase and phosphoenolpyruvate competitively for pyruvate kinase. In both cases, the K i of the pyrimidine nucleotide and K m of the glycolytic substrate were above their intraerythrocytic concentrations. CTP was a competitive inhibitor of ADP for pyruvate kinase with a K i near its intraerythrocytic concentration. CDP-choline and CDP-ethanolamine had no effect on the activities of EmbdenMeyerhof or pentose phosphate shunt enzymes. Thus, the nature of the hemolytic anemia in hereditary P5′N deficiency remains enigmatic.

Concurrent sickle cell anemia and alpha-thalassemia. Effect on pathological properties of sickle erythrocytes.

The concurrence of sickle cell anemia and alpha-thalassemia results in less severe hemolytic anemia apparently as a result of reduced intraerythrocytic concentration of hemoglobin S and its retarded polymerization. We have evaluated the effect of alpha-globin gene number on several interrelated properties of sickle erythrocytes (RBC) that are expected to correlate with the hemolytic and rheologic consequences of sickle cell disease. The irreversibly sickled cell number, proportion of very dense sickle RBC, and diminished deformability of sickle RBC each varied directly with alpha-globin gene number. Sickle RBC density was a direct function of the mean corpuscular hemoglobin concentration (MCHC). Even in nonsickle RBC, alpha-globin gene number varied directly with RBC density. Despite differences in alpha-globin gene number, sickle RBC of the same density had the same degree of deformability and dehydration. These data indicate that the fundamental effect of alpha-thalassemia is to inhibit the generation of sickle RBC having high density and MCHC, and that the other beneficial effects of sickle RBC are secondary to this process. The less consistent effect on overall clinical severity reported for subjects with this concurrence may reflect an undefined detrimental effect of alpha-thalassemia, possibly on the whole blood viscosity or on sickle RBC membrane-mediated adherence phenomena.

Respiration during chronic hypoxia and hyperoxia in larval and adult bullfrogs (Rana catesbeiana). II. Changes in respiratory properties of whole blood.

Rana catesbeiana Shaw tadpoles and adults were maintained at 20-23 degrees C under aerial and aquatic normoxia (PO2 150 mmHg), hyperoxia (PO2 275 mmHg) and hypoxia (PO2 75 mmHg) for 4 weeks, after which the following blood measurements were made: haematocrit, red blood cell count, haemoglobin concentration, mean corpuscular haemoglobin concentration, O2 capacity, O2 equilibrium curve, Bohr shift, Hill's coefficient and intraerythrocytic concentration of nucleotide triphosphates (ATP + GTP) and 2,3-DPG. Normoxic tadpoles had much higher blood O2 affinity (P50 9-10 mmHg) than adults (P50 35 mmHg) but a lower haemoglobin concentration, haematocrit and O2 capacity. The concentration of intraerythrocytic phosphates was higher in normoxic tadpoles than in adults, indicating that the higher O2 affinity of normoxic tadpole blood was due to the haemoglobins themselves, rather than affinity modulators. Chronic hypoxia in tadpoles produced little change in whole blood P50, and no significant change in any other blood variable. In adult bullfrogs, on the other hand, O2 capacity doubled through polycythaemia, and the P50 decreased by 11 mmHg (35%), though apparently not from any significant change in concentration of intraerythrocytic phosphates. Hyperoxia produced no haematological changes in either larvae or adults. In adult bullfrogs exposed to chronic hypoxia, the morphology of the gas exchange organs does not change (Burggren & Mwalukomo, 1983), but instead profound adjustments occur in the blood, favouring O2 transport under these conditions. The blood of the tadpole shows little or no response to chronic hypoxia, with morphological adjustments in skin, gills and lungs constituting the major response.