[Short courses of iodine-bromine bath therapy and physical exercises for patients with coronary heart disease and concomitant cardiac rhythm disturbance].

The objective of this sanatorium-based study was to evaluate effect of short courses of iodine-bromine bath therapy and veloergometer exercises during 14 days on the working capacity, ventricular and supraventicular extrasystoles, painful and "silent" myocardial ischemia in patients with a combination of coronary heart disease (CHD), stable angina of functional class II, and grade II hypertensive disease (according to the WHO classification). The patients' conditions were monitored by means of spiroveloergometry and Holter ECG recordings. The study included a total of 108 patients. It was shown that short courses of iodine-bromine bath therapy and veloergometer exercises had training and anti-arrhythmic effect on the patients with concurrent coronary heart disease, stable angina, and hypertensive disease. The treatment improved their working capacity, enhanced coronary heart reserve, reduced the frequency of ventricular and supraventicular extrasystoles, decreased manifestations of painful and "silent" myocardial ischemia.

Crystal structure of the human acyl protein thioesterase I from a single X-ray data set to 1.5 A.

BACKGROUND: Many proteins undergo posttranslational modifications involving covalent attachment of lipid groups. Among them is palmitoylation, a dynamic, reversible process that affects trimeric G proteins and Ras and constitutes a regulatory mechanism for signal transduction pathways. Recently, an acylhydrolase previously identified as lysophospholipase has been shown to function as an acyl protein thioesterase, which catalyzes depalmitoylation of Galpha proteins as well as Ras. Its amino acid sequence suggested that the protein is evolutionarily related to neutral lipases and other thioesterases, but direct structural information was not available. RESULTS: We have solved the crystal structure of the human putative Galpha-regulatory protein acyl thioesterase (hAPT1) with a single data set collected from a crystal containing the wild-type protein. The phases were calculated to 1.8 A resolution based on anomalous scattering from Br(-) ions introduced in the cryoprotectant solution in which the crystal was soaked for 20 s. The model was refined against data extending to a resolution of 1.5 A to an R factor of 18.6%. The enzyme is a member of the ubiquitous alpha/beta hydrolase family, which includes other acylhydrolases such as the palmitoyl protein thioesterase (PPT1). CONCLUSIONS: The human APT1 is closely related to a previously described carboxylesterase from Pseudomonas fluorescens. The active site contains a catalytic triad of Ser-114, His-203, and Asp-169. Like carboxylesterase, hAPT1 appears to be dimeric, although the mutual disposition of molecules in the two dimers differs. Unlike carboxylesterase, the substrate binding pocket and the active site of hAPT1 are occluded by the dimer interface, suggesting that the enzyme must dissociate upon interaction with substrate.

Enhanced Na+/H+ exchange in Cushing's syndrome reflects functional hypermineralocorticoidism.

BACKGROUND: Patients with Cushing's syndrome exhibit a bimodal distribution of maximal rates of the erythrocyte amiloride-sensitive Na+/H+ exchange (NHE). Enhanced erythrocyte NHE has recently been found in patients with primary aldosteronism. OBJECTIVE: To test the hypothesis that occult hypermineralocorticoidism in a subset of patients with Cushing's syndrome is responsible for the greater than normal NHE. METHODS: NHE was measured as maximal initial rate (Vmax) of amiloride-inhibited efflux of H+ into an alkaline Na+-containing medium, for 47 patients with hypercortisolism (20 with pituitary adenomas, 18 with adrenal adenomas, and nine with ectopic production of adrenocorticotropin). Clinical appearance, blood pressure levels, plasma aldosterone and deoxycorticosterone levels, serum electrolytes, and urine (tetrahydrocortisol plus 5-alpha-tetrahydrocortisol) : tetrahydrocortisone ratios were assessed for all patients. Twenty patients (10 with greater than normal NHE and 10 with low-to-normal NHE) were randomly selected from 47 patients with hypercortisolism, and treated with 200 mg/day spironolactone for 7 days. NHE in these patients was assessed before starting the treatment and 2 days after its cessation. RESULTS: Greater than normal NHE (Vmax) was associated with peripheral edema, high diastolic blood pressure, hypokalemia, and high urine (tetrahydrocortisol plus 5-alpha-tetrahydrocortisol) : tetrahydrocortisone ratios. The enhanced NHE was rapidly normalized by treatment with spironolactone. CONCLUSION: Erythrocyte NHE in patients with hypercortisolism and functional hypermineralocorticoidism is greater than normal due to incomplete peripheral conversion of cortisol (which binds to mineralocorticoid receptors) into metabolically inactive cortisone.

Can we use erythrocytes for the study of the activity of the ubiquitous Na+/H+ exchanger (NHE-1) in essential hypertension?

Both Na+/Li+ countertransport and electrochemical proton gradient (delta mu(H+))-induced Na+ and H+ fluxes are increased in erythrocytes from patients with essential hypertension. It was assumed that these abnormalities are related to ubiquitous (housekeeping) forms of the Na+/H+ exchanger (NHE-1). To examine this hypothesis, we compared kinetic and regulatory properties of erythrocyte Na+/Li+ countertransport and delta mu(H+)-induced Na+ and H+ fluxes with data obtained for cloned isoforms of the Na+/H+ exchanger. In human erythrocytes, Na+/Li+ countertransport exhibited a hyperbolic dependence on [Na+]0 with a K0.5 of approximately 30 to 40 mmol/L. The activity of this carrier was increased by two-fold in the fraction of erythrocytes enriched with the old cells, was inhibited by 0.1 mmol/L phloretin, and was insensitive to both 1 mmol/L amiloride and ATP depletion. In contrast, delta mu(H+)-induced 22Na influx was exponentially increased at [Na+]0 > 60 mmol/L, was insensitive to phloretin, was partly decreased by both 1 mmol/L amiloride and ATP depletion, and was the same in total erythrocytes and in the old cells. The values of Na+/Li+ countertransport and delta mu(H+)-induced Na+ influx in erythrocytes from different species were not correlating and their ratio in human, rat, and rabbit erythrocytes was 10:1:170 and 1:5:1 for Na+/ Li+ countertransport and delta mu(H+)-induced Na+ influx, respectively. In contrast to the majority of nonepithelial cells and cells transfected with an ubiquitous isoform of Na+/H+ exchanger, both delta mu(H+)-induced Na+ influx and Na+/Li+ countertransport in human erythrocytes were completely insensitive to ethylisopropyl amiloride (20 micromol/L) and cell shrinkage. Thus, our data strongly suggest that human erythrocyte Na+/Li+ countertransport and delta mu(H+)-induced Na+/H+ exchange are mediated by the distinct transporters. Moreover, because the properties of these erythrocyte transporters and NHE-1 are different, it complicates the use of erythrocytes for the identification of the mechanism for activating the ubiquitous form of Na+/H+ exchanger in primary hypertension.

Volume-dependent regulation of ion carriers in human and rat erythrocytes: role of cytoskeleton and protein phosphorylation.

This study examines the effect of heat-induced cytoskeleton transitions and phosphoprotein phosphatase inhibitors on the activity of shrinkage-induced Na+, K+, 2Cl- cotransport and Na+/H+ exchange in rat erythrocytes and swelling-induced K+, Cl- cotransport in human and rat blood cells. Preincubation of human and rat erythrocytes at 49 degrees C drastically activated K+, Cl- cotransport and completely (rat) or partly (human) abolished its volume-dependent regulation. The same procedure did not affect basal activity of Na+, K+, 2Cl- cotransport but completely abolished its activation by shrinkage thus suggesting the involvement of a thermosensitive element of cytoskeleton network in the volume-dependent regulation of cotransporters. Both the shrinkage- and electrochemical proton gradient-induced Na+/H+ exchange was inhibited by the heat treatment to the same extent (50-70%), thus indicating the different signaling pathways involved in the activation of Na+, K+, 2Cl- cotransport and Na+/H+ exchange by cell shrinkage. This suggestion is in accordance with data on the different kinetics of volume-dependent activation and inactivation of these carriers as well as on their sensitivity to medium osmolality. Both swelling- and heat-induced increments of K+, Cl- cotransport activity were diminished by inhibitors of phosphoprotein phosphatases (okadaic acid and calyculin). In rat erythrocytes these compounds potentiate shrinkage-induced Na+/H+ exchange. On the contrary, neither basal nor shrinkage-induced Na+, K+, 2Cl- cotransport was affected by these compounds. Our results indicate a key role of cytoskeleton network in volume-dependent activation of K+, Cl- and Na+, K+, 2Cl- cotransport and the involvement of protein phosphorylation-dephosphorylation cycle in regulation of the activity of K+, Cl- cotransport and Na+/H+ exchange.

Increased Na+,K(+)-pump activity in erythrocytes of rabbits fed cholesterol.

Na+,L(+)-pump activity, intracellular sodium, potassium and magnesium concentrations and membrane cholesterol content were studied in erythrocytes of rabbits fed cholesterol. The average activity of the Na+,K(+)-pump in erythrocytes of rabbits with high plasma cholesterol was twice that in erythrocytes of control animals. Analysis showed a positive correlation between the pump activity and plasma cholesterol. The sodium content in erythrocytes correlated negatively with plasma cholesterol, as well as with the Na+,K(+)-pump activity. No significant differences in potassium and magnesium concentrations or in the membrane cholesterol content were observed between the two groups. The results indicate that modulation of the pump activity by cholesterol is not necessarily mediated by changes in the membrane viscosity.

[Transport of monovalent cations into erythrocytes of rabbits with experimental hypercholesterolemia: correlation with plasma cholesterol]. / Transport odnovalentnykh kationov v éritrotsitakh krolikov s éksperimental'noi giperkholesterinemiei: korreliatsii s kholesterinom plazmy.

The activities of the Na+, K(+)-pump, Na+, K+, 2Cl- and K+, Cl(-)-cotransports and Na+, Li+ exchange as well as intracellular concentrations of Na+, K+, Mg2+ and cholesterol content in erythrocyte membranes of rabbits with experimental hypercholesterolemia have been studied. The activity of the Na+, K(+)-pump recorded as the ouabain-inhibited component of 86Rb influx is, on the average, by 100% higher than that in control erythrocytes of rabbits fed on a cholesterol-rich diet for 2 months and correlates significantly with the concentration of cholesterol (Ch) and low density lipoproteins (LDL) in the plasma as well as with Na+ concentration in erythrocytes. The activity of the Na+, K+, 2Cl- and K+, Cl(-)-cotransports recorded, correspondingly, as the bumetanide- and furosemide-inhibited component of 86Rb influx, is unobserved in rabbit erythrocytes irrespective of the Ch level in the plasma. The activity of the Na+, Li+ exchange is markedly reduced in erythrocytes of rabbits with hypercholesterolemia and correlates with Ch and LDL levels in the plasma. The K+ and Mg2+ concentrations in erythrocytes do not depend on Ch plasma levels. There was a negative correlation between the intracellular Na+ content with plasma Ch and LDL levels. The Ch content in erythrocyte ghosts is, on the average, identical for both groups of experimental animals.

[Na+/H+- and Na+/Na+-countertransport in human, rabbit, and rat erythrocytes: evidence for the existence of two independent ion-transporting systems]. / Na+/H+- i Na+/Na+-protivotransport v éritrotsitakh cheloveka, krolika,i krysy: dokaztel'stva sushestvovaniia dvukh nezavisimykh ion-transportiruiushchikh sistem.

The activity and regulatory features of the Na+/H(+)- and Na+/Na(+)-exchange were studied in human, rabbit and rat red blood cells. No basal activity of the Na+/H(+)-exchange (the amyloride-inhibited component of the 22Na+ influx) in erythrocytes of these species was observed. The rate of 22Na+ influx increased rapidly when the experiments were carried out on acid-loaded cells in an alkaline (pH0 = 8.0) incubation medium (delta mu H(+)-induced Na+/H(+)-exchange). The ratio of delta mu H(+)-induced Na+/H(+)-exchange activities in human, rabbit and rat red blood cells was 1.0 : 1.1 : 2.3, respectively, whereas that of the Na+/Na(+)-exchange activities (the phloretin-inhibited component of the 22Na+ influx) in erythrocytes of these species was 1.0 : 4.6 : 0.2. The osmotic shrinkage of rat and rabbit erythrocytes led to the stimulation of the Na+/H(+)- (but not Na+/Na+) exchange. Amyloride (1 mM) inhibited the shrinkage-induced 22Na+ entry as well as the delta mu H(+)-induced 22Na+ entry--by 95 and 10-20%, respectively. Heat treatment (10 min, 49-51 degrees C), disturbing the membrane cytoskeleton suppressed both the shrinkage-induced activation and the delta mu H(+)-induced activation of the Na+/H(+)-exchange. The data obtained indicate that the both transport systems are mediated by two distinct transport carriers. It may be suggested that the delta mu H(+)-induced Na+/H(+)-exchange, on the one hand, and the shrinkage-induced Na+/H(+)-exchange, on the other, are mediated by two different Na+/H(+)-exchanger subtypes.

[The compartmentalization of membrane-bound thrombocyte calcium in arterial hypertension]. / Kompartmentalizatsiia membranno-sviazannogo kal'tsiia trombotsitov pri arterial'noi gipertenzii.

High contents of Ca2+ was revealed in thrombocytes' intracellular compartments in patients with essential hypertension. In response to different stimuli, large amount of Ca2+ can be released in the platelets of the patients which makes a considerable contribution to generation of the Ca2+ signal and activation of thrombocytes in cardiovascular diseases.

[The membrane-bound calcium of the thrombocytes in essential hypertension]. / Membranno-sviazannyi kal'tsii trombotsitov pri éssentsial'noi gipertenzii.

The investigation was aimed at analyzing membrane-bound calcium in platelets of patients with essential hypertension (EH) and of healthy persons. 55 men were examined. Of these, 38 presented with EH and 17 were healthy. Membrane-bound calcium determined with the help of the chlortetracycline fluorescent probe. The level of membrane-bound calcium in intracellular compartments was higher in patients with EH than in the control. The kinetic curves of the binding of the chlortetracycline fluorescent probe with cellular membranes allow one to reveal disturbances of calcium-dependent membrane processes in persons suffering from EH.