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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ca binding in the red blood cell (RBC) membrane of spontaneously hypertensive rats (SHR) and of patients with essential hypertension was studied. Under conditions of physiological concentration of free Ca in the incubation medium of RBC the outer part of the membrane binds 393 +/- 32 and 435 +/- 30 nmole of Ca per ml of RBC in rats and humans, respectively, without essential differences in the amount of Ca in hypertensive individuals as compared to the normotensive controls. The membrane of red blood cell ghosts (RBCgh) at concentrations of free Ca corresponding to its intracellular concentration binds 4.28 +/- 0.39 and 3.53 +/- 0.15 nmole of Ca per mg of protein of RBCgh in rats and humans, respectively. This part of membrane-bound Ca pool (most probably related to the inner part of the red blood cell membrane) is reduced by 48% in SHR and by 28% in patients with essential hypertension as compared to normotensive controls. It is suggested that the decrease of Ca binding ability of the RBC membrane in both types of hypertension studied may be a pattern of a more widespread cell membrane defect.
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PMID:Decrease of calcium binding by the red blood cell membrane in spontaneously hypertensive rats and in essential hypertension. 57 Nov 15

Neutrophils possess a plasma-membrane-bound reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase which catalyzes superoxide (O2-) formation and is activated by a variety of stimuli. Recently, neutrophils of patients with essential hypertension (EHT) have been reported to generate O2- at rates up to fourfold higher than those of normotensive (NT) subjects upon exposure to the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMet-Leu-Phe). We studied regulation of O2- formation in neutrophils of 25 EHT subjects and 25 age- and sex-matched NT subjects. The intercellular signal molecules fMet-Leu-Phe, platelet-activating factor and leukotriene B4 activated O2- formation in neutrophils, but the latter two receptor agonists were less effective than the former. fMet-Leu-Phe activated O2- formation with a 50% effective concentration (EC50) of about 30 nmol/l, the effect of the chemotactic peptide being maximal at 0.1-1 mumol/l. fMet-Leu-Phe-induced O2- formation was potentiated by platelet-activating factor, adenosine 5'-[gamma-thio]triphosphate and cytochalasin B and was inhibited by the activators of adenylyl cyclase, isoproterenol, prostaglandin E1 and histamine. 4 beta-Phorbol 12-myristate 13-acetate, 1,2-dioctanoyl-sn-glycerol, gamma-hexachlorocyclohexane and arachidonic acid, which circumvent receptor stimulation, also activated O2- formation. Significant differences between NT and EHT subjects were not evident in respect of any of the parameters studied. Our data suggest that regulation of the neutrophil NADPH oxidase is not disturbed in EHT and that altered O2- formation does not represent a genetic marker for abnormalities in plasma-membrane signal transduction in EHT.
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PMID:Regulation of the superoxide-forming NADPH oxidase of human neutrophils is not altered in essential hypertension. 184 30

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.
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PMID:[The membrane-bound calcium of the thrombocytes in essential hypertension]. 194 59

A 3-fold higher concentration of "endogenous digitalis" is found in the serum of patients with essential hypertension than in the serum of normotensives, whose concentration was determined in 22 normotensive probands by an receptor assay using isolated (Na+ + K+)-ATPase as 76.3 +/- 9.3 nM ouabain equivalents. Since the concentration of "endogenous digitalis" was 7-19 fold higher in 2 patients, who had become uremic due to a malignant hypertension and since their serum levels fell 3-fold by hemodialysis, the hemofiltrate was used for partial purification of the substance. This was possible by hydrophobic chromatography on Amberlite XAD-2, octadecyl-coated silica gel, anion exchange chromatography and affinity chromatography on membrane-bound (Na+ + K+)-ATPase. The partially purified substance behaved like the material described by Cloix et al. (1985) Biochem. Biophys. Res. Commun. 131:1234-1240 and competed with digoxin for digoxin antibodies. Ascorbic acid isolated on the search for an inhibitor of (Na+ + K+)-ATPase from beef brain inhibited [3H]ouabain binding due to a decrease of the ouabain binding sites by a reduction of a group within the ATP binding site of the enzyme. Unsaturated fatty acids claimed to be "endogenous digitalis (Tamura et al. [1985] J. Biol. Chem. 260:9672-9677)" also lowered the capacity of the cardiac glycoside binding site but did not compete with ouabain.
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PMID:Sodium pump inhibitor in the serum of patients with essential hypertension and its partial purification from hemofiltrate. 243 45

There is a growing evidence for that in modern societies the function of the cellular sodium-potassium pump (membrane-bound Na+ K+ ATPase) in several tissues in man cannot respond adequately to demands. This is not seen in any other free-living vertebrates on this earth. The clearly unphysiological very high intake of sodium-chloride (salt) and also alcohol is definitely playing an important role in the development of the common degenerating metabolic aberrations, e.g. essential hypertension, diabetes II and severe over-weight, in man. The special and overall important role of the sodium-potassium pump for optimal cellular function and regeneration with special reference to the vascular tissues is presented and discussed.
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PMID:The sodium pump and energy regulation: some new aspects for essential hypertension, diabetes II and severe overweight. 258 82

Evidence has been provided on the increased presence, in essential hypertension, of endogenous digitalis-like factor(s) [DLIS, digoxin-like immunoreactive substance(s)] able to cross-react with antidigoxin antibodies and to inhibit the membrane-bound sodium-potassium pump. An inhibition of the sodium pump could lead, in smooth muscle cells, to an increase of intracellular calcium ions and to an increase of total peripheral resistances. In this study the relation between plasma levels of DLIS and the acute hypotensive effect of a calcium antagonist (nifedipine) has been evaluated in a group of borderline to severe hypertensive patients and in a control group of normotensive subjects. The results obtained confirm that the hypotensive effect of nifedipine is related to pretreatment blood pressure and show, only in hypertensive patients, a significant relation of DLIS with both pretreatment blood pressure and blood pressure decrement induced by nifedipine. These findings are compatible with a possible role of DLIS in modulating cellular calcium handling.
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PMID:Acute hypotensive effect of calcium antagonists and endogenous digitalis-like immunoreactivity in human essential hypertension. 303 84

The rate of calcium transport and calmodulin distribution in the erythrocytes of patients with essential hypertension were studied. In erythrocyte membranes subjected to calmodulin depletion by treatment with EGTA, both the affinity of the calcium pump for Ca2+ and its maximal activity were the same in normotensive and hypertensive patients. The addition of exogenous calmodulin to calmodulin-stripped membranes from erythrocytes of patients with essential hypertension resulted in a smaller increase of the maximal activity of the calcium pump and its affinity for Ca2+. The addition of calmodulin to erythrocyte membranes obtained without EGTA treatment resulted in a smaller increase of the maximal activity of the calcium pump only. There were no significant differences of calmodulin distribution (cytoplasmic concentration and size of the membrane-bound pool) between the erythrocytes of normotensive and hypertensive patients. It is suggested that alterations in the calcium pump activity of the erythrocyte membranes of patients with essential hypertension are related to the alteration of interaction between calmodulin and Mg2+, Ca2+-ATPase.
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PMID:Calmodulin distribution and Ca2+ transport in the erythrocytes of patients with essential hypertension. 632 Oct 88

The membrane-bound Na/K-ATPase system is an important energy regulating system for all primate cells and is suspected to be either primary or secondary affected in different but important metabolic disorders as essential hypertension, diabetes II (mature onset diabetes) or severe overweight. Rabbit smooth muscle cells grown in culture have been incubated with different concentrations of ouabain (10(-7)-10(-4) mol/l) and potassium (4 and 6 mmol/l). In controlled series, the incorporation of 3H-thymidine (and collagen secretion) during incubation with ouabain was found to be diminished by at maximum 73% (P less than 0.01) and this was found to be reversible by changing to ouabain-free medium or partly by the addition of extra potassium. The intracellular ATP level and lactate production was diminished together with the fall in 3H-thymidine incorporation. These effects were probably not due to a non-specific toxic effect of ouabain because no difference in leakage of prelabelled 3H-thymidine from cells compared to control series was seen. We suggest that an optimal function of the membrane-bound Na/K-ATPase system is of great importance not only for intracellular energy production but also for cell proliferation and protein synthesis.
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PMID:Effects of ouabain and potassium on rabbit arterial smooth muscle cells in culture. 632 36

Hypertension and kidney dysfunction in sodium transport observed in the Milan hypertensive strain (MHS) of rats are genetically associated with point mutations of adducin, an actin- and spectrin-binding protein of the membrane cytoskeleton. Polymorphism in the adducin locus has been reported to occur also in cases of human primary hypertension. In this study we show by immunostaining that adducin is localized along the basolateral epithelial membrane surface of the entire proximal and distal tubule with no detectable differences between MHS rats and the normotensive control strain (MNS). However, the total amount of adducin in kidney homogenates is reduced by about 45% in MHS rats as determined by quantitative immunoblotting. In erythrocyte membranes of MHS rats, adducin is reduced approximately 10%. The reduction of renal adducin in MHS rats is mainly caused by a reduction of the adducin pool that is loosely associated with kidney membranes and can be released by the non-ionic detergent, Triton X-100. The Triton-resistant, tightly membrane-bound pool of renal adducin differed by approximately 10% between MHS and MNS rats. Since several ion transporters have been shown to be tethered to the membrane cytoskeleton, we suppose that the reduction of the dynamic, loosely bound pool of adducin in MHS rats might interfere with the normal turnover and incorporation of yet unknown transporters involved in kidney sodium transport. However, the Na+,K+-ATPase appears to be not involved, as indicated by normal distribution and amounts of NA+,K+-ATPase in the kidney of MHS rats revealed by immunostaining and immunoblotting.
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PMID:Localization and quantification of the cytoskeleton-associated protein adducin in the kidneys of normal and Milan hypertensive rats. 950 78

The purpose of this study was to determine whether tissue neutral endopeptidase (NEP) 24.11 activity, a membrane-bound metalloenzyme widely distributed in the peripheral circulation that cleaves and inactivates vasodilator peptides, is increased in spontaneously hypertensive hamsters relative to genetically/age-matched normotensive hamsters. Mean arterial pressure and heart rate were 163 +/- 11 mm Hg and 312 +/- 7 beats/min in spontaneously hypertensive hamsters and 99 +/- 3 mm Hg and 302 +/- 10 beats/min in normotensive hamsters, respectively (mean +/- SEM). NEP 24.11 activity is significantly increased in the kidney, cheek pouch, and spinotrapezius muscle, and significantly decreased in the heart and aorta of spontaneously hypertensive hamsters relative to controls (P < .05). Lung and brain NEP 24.11 activity is similar in both groups. Renal NEP 24.11 activity increases and to a similar extent in spontaneously hypertensive and normotensive hamsters as chloride anion concentration in the assay buffer is increased. Substituting citrate for chloride anion significantly attenuates renal NEP 24.11 activity. Taken together, these data indicate that NEP 24.11 activity in spontaneously hypertensive hamsters is increased in two organs that contribute appreciably to peripheral vascular resistance, skeletal muscle, and kidney. We suggest that the spontaneously hypertensive hamster is a suitable model to study the role of skeletal muscle and renal NEP 24.11 in regulating vasomotor tone in essential hypertension.
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PMID:Increased tissue neutral endopeptidase 24.11 activity in spontaneously hypertensive hamsters. 963 95


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