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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This presentation has reviewed evidence from our laboratory that both structural and functional changes participate in the initiation and maintenance of hypertension in spontaneously hypertensive rats (SHR). Structural changes are present in the muscular arteries of the mesenteric and renal vasculature at 3- to 5-week-old SHR as compared with WKY. The major structural change in SHR arteries was increased cross-section area with increased thickness of the media owing to hyperplasia of smooth muscle; lumen sizes were interchanged. Later, at 10-12, 21, and 28 weeks of age, there was further increase in medial thickness owing to hyperplasia, and some hypertrophy and changes in elastic arteries also became evident. Increases in medial thickness of elastic arteries included hypertrophy as well as hyperplasia. Changes in lumen diameter were never observed in arteries fixed in a relaxed state at physiological flow rates. In addition, a deficit in Ca handling (decreased ATP-dependent Ca2+ accumulation) was observed in plasma-membrane vesicles from mesenteric arteries of SHR prior to and after the development of hypertension. It persisted when hypertension was reversed by hydralazine in SHR. It was present in various forms of experimental hypertension. It was present whenever hypertension was present and disappeared with normalization of blood pressure by withdrawal of the stimulus. The Ca-handling deficit was found in several nonarterial tissues and may be a generalized genetic defect in SHR. It was always accompanied by increased alkaline phosphatase activity of plasma membranes, and this was suggested to reflect the smooth-muscle hyperplasia occurring simultaneously. A model of the initiation and maintenance of hypertension based on medial thickening and deficient Ca handling as primary, interacting causes of genetic hypertension is proposed.
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PMID:Early structural changes in precapillary vessels in hypertension and their relationship to functional changes. 608 10

Three different pressure groups of rats, stroke-prone spontaneously hypertensive rats (SHRSP, 200-270 mmHg), stroke-resistant SHR (SHRSR, 160-240 mmHg), and Wistar rats (WR, 120-160 mmHg) were used to investigate the effect of prior existing hypertension on the severity of brain damage induced by ischemia. The cerebral ischemia was induced by bilateral common carotid artery ligation (BLCL) and the survival rate, cerebral blood flow, cerebral energy metabolites (ATP, lactate c-AMP) and water content were measured. Colloidal carbon perfusion was also performed. Sixteen-week-old male rats were used. The survival rate was observed until 24 hours after BLCL. Cerebral blood flow was measured in parietal cortex by hydrogen clearance method. ATP was measured by luciferin-luciferase method, and lactate by enzymatic method using LDH. c-AMP was measured by radioimmunoassay. Brain water content was measured by freeze-dry method. These measurements were done for animals surviving 6 hours of BLCL. Colloidal carbon perfusion was done according to Ames' Method. The survival rate was lower in the hypertension group. The survival of SHRSP and SHRSR were 20% compared to 71% in WR after 24 hours of BLCL. The cerebral circulation of SHRSP fell abruptly and was near to zero after one hour of BLCL. In SHRSR this fall of cerebral blood flow was prominent in the rats of higher blood pressure. On the other hand there was no apparent fall of cerebral blood flow in WR after BLCL. The cerebral energy metabolites. ATP and c-AMP showed the lowest level in SHRSP which had the negative correlation to blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Experimental cerebral ischemia after bilateral common carotid artery ligation in SHRSP, SHRSR and Wistar rats: correlation between blood pressure and degree of ischemia]. 609 92

The present study focuses on the interaction between cadmium (Cd) and the Na, K-ATPase system in in vitro grown vascular smooth muscle cells (VSMCs) derived from the rat carotid artery. In disrupted VSMCs rendered permeable by osmotic shock, Cd inhibited Na, K-ATPase; I50 was reached at 10(-5) M Cd. Mg-ATPase was also inhibited by Cd; I50 was attained at concentrations of 10(-4) M Cd. Cd inhibition of Na,K-ATPase in the VSMCs was noncompetitive with respect to Na, K, and ATP. Rubidium transport experiments performed with intact VSMCs demonstrated that within an incubation period of 150 minutes, a concentration of 10(-4) M Cd in the extracellular fluid exerted no acute effect on the Na-K pump. Within this time interval, intracellular Cd attained a concentration eightfold higher than the extracellular Cd concentration. Thus, it appears that under acute conditions Cd exerts its inhibitory effect on Na, K-ATPase only in disrupted VSMCs. The data further suggest that, in the VSMC, conditions under which Cd inhibits Na, K-ATPase are consistent with inhibition from the cytoplasmic side of the cell membrane.
Hypertension
PMID:Cadmium effect on the Na,K-ATPase system in cultured vascular smooth muscle cells. 614 Nov 42

It has been demonstrated in experiments on cats and rabbits that a single and chronic administration of pentamine (1 mg/kg) produced a distinct variation in carbohydrate-energy metabolism in the tissue of different blood vessels, enhancing the glycolytic formation of ATP. Chronic administration of pentamine corrected metabolic disorders in rabbit vascular tissue in experimental pituitrin-induced hypertension.
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PMID:[Effect of pentamine on vascular tissue metabolism in experimental vascular pathology]. 620 Mar 58

Sodium pumps of cardiac plasma membranes were studied in young, spontaneously hypertensive rats (SHR) and in their normotensive controls (Wistar-Kyoto; WKY) using the two following methods. The enzymatic activity and its sensitivity to ouabain were measured as the Na+, K+ -dependent ATP hydrolysis, and the number of pumps was estimated by [3H] ouabain binding. The main results of this study were the observations that (a) concentrations of ouabain as low as 10(-10) M inhibited 10-15% of the enzyme activity in both strains; (b) Na+, K+- adenosine triphosphatase (ATPase) activity in membranes from SHR was double that in membranes from WKY (16.5 +/- 3.2 mumol Pi/h/mg protein vs. 8.2 +/- 1.2 mumol Pi/h/mg protein for 10(-7) M ouabain; p less than 0.01); (c) sensitivity to three different cardiac glycosides, ouabain, digoxin, and digitoxigenin, was identical in SHR and WKY vesicles; and (d) the binding capacity of [3H] ouabain was significantly higher in SHR than in WKY vesicles, but the dissociation constant (KD) did not appear to differ between the two substrains. These studies, performed on 3-week-old rats before the appearance of hypertension, showed, on the one hand, the existence of a Na+, K+ -ATPase of very high affinity in the rat heart, and, on the other, that cardiac sarcolemmal membranes from SHR had a greater number of sodium pumps than those from WKY and thus a greater ability to extrude sodium.
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PMID:Quantitative changes in cardiac Na+, K+ -adenosine triphosphatase of spontaneously hypertensive rats. 620 Jul 16

Age-related changes in the myocardial energy metabolism were studied in spontaneously hypertensive (SHR) rats of 5-15 weeks of age. Systolic blood pressure increased rapidly during 5 to 10 weeks of age (developing phase) and attained a plateau level at 10 to 15 weeks (sustained phase). Even during the developing phase, the heart was hypertrophic, as assessed by an increase in the ratio of the ventricular weight to body weight. However, myocardial contents of glycolytic intermediates and high energy phosphate compounds and thus, the myocardial energy state (phosphorylation potential) in SHR rats did not differ from those in age-matched normotensive Wistar-Kyoto (WKY) rats. The lactate/pyruvate ratio was significantly lower in SHR rats. On the other hand, during the sustained phase, cardiac hypertrophy progressed only gradually, and myocardial contents of creatine phosphate and ATP were lower, while the lactate content was higher than in WKY rats. The lactate/pyruvate ratio was elevated, while phosphorylation potential was lowered. These findings suggest that the energy state is normal during the developing phase of hypertension despite the presence of cardiac hypertrophy and the increased pressure load, whereas the energy state is at a lower level during the sustained phase of hypertension.
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PMID:Myocardial energy metabolism in the hypertrophied hearts of spontaneously hypertensive rats. 621 80

Protein content, enzymatic activites and Ca2+ accumulation capacities were studied in plasma membrane fractions isolated from mesenteric arteries of rats made hypertensive by renal artery stenosis with and without contralateral nephrectomy, i.e., one-kidney, one clip (1-KHR) and two-kidney, one clip (2-KHR) hypertension, respectively. Both types of renovascular hypertension showed similar vascular plasma membrane abnormalities which included increased total protein contents, enhanced alkaline phosphatase activities and reduced ATP-dependent Ca2+ accumulation compared to control values. The altered alkaline phosphatase activity and ATP-dependent Ca2+ accumulation appeared to be associated with blood pressure elevation in both types of hypertension and may be related to the elevation of blood pressure insensitive to captopril (SQ 14,225) in 1-KHR and 2-KHR. These results are consistent with the current concept of biochemical abnormalities of arterial smooth muscle in the development ostem.
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PMID:Characteristics of arterial plasma membrane in renovascular hypertension in rats. 624 53

Recently it has been claimed that the active potassium influx in erythrocytes of patients with essential hypertension would be increased. In view of the diagnostic and possibly therapeutic potential of this claim, we have determined the Na+-K+ activated ATPase activity and the affinity of the enzyme for Na+, K+, and ATP in membranes isolated from erythrocytes of hypertensive (with and without medication) and normotensive subjects. Subsequently, the active (ouabain-sensitive) sodium and potassium fluxes and their ratios have been determined after treatment of intact erythrocytes either with cold or with p-chloromercuribenzene-sulfonate (PCMBS). Finally, in view of a subsequent claim that the furosemide-sensitive, ouabain-insensitive cation fluxes would be greatly reduced in erythrocytes of patients with essential hypertension, we have determined these fluxes in choline chloride medium containing ouabain with and without furosemide. For none of these parameters has any significant difference between hypertensive and normotensive subjects been found except for a decrease in the ouabain-sensitive K+ influx after cold treatment in hypertensives. This is also true for the hypertensive subjects who had a known hypertensive parent. It is concluded that the results do not support a role of Na+-K+ activated ATPase or the furosemide-sensitive cation carrier in the pathogenesis of essential hypertension, and that ouabain-sensitive and furosemide-sensitive cation flux determinations in erythrocytes do not seem to be useful for the diagnosis of this condition.
Hypertension
PMID:Cation fluxes and Na+-K+-activated ATPase activity in erythrocytes of patients with essential hypertension. 627 69

To study the relative roles of sodium (Na+) and calcium ions (Ca2+) in the response of adrenal glomerulosa cells, we investigated the effects of different Na+ concentrations in the incubation media and the actions of substances that interfere with Ca2+ fluxes. Basal aldosterone secretion and response to angiotensin II (AII), adrenocorticotropic hormone (ACTH), or potassium (K+) were dependent on extracellular Na+ concentration. Veratridine, a Na+ channel opener that dissipates Na+ gradients, blocked the stimulated steroidogenic response. Mersalyl acid and tetracaine, which are potent Ca2+ antagonists, blocked the effects of aldosterone secretagogues. Divalent cations with Ca2+ antagonistic action such as manganese M(n2+), nickel (Ni2+), and cobalt (Co2+) blocked the aldosterone secretory response to AII, ACTH, and K+. Barium (Ba2+) and strontium (Sr2+), known to mimick Ca2+ effects, increased or did not affect responses of the glomerulosa cells. Sodium vanadate, an inhibitor of ATP-dependent Ca2+ translocation, did not alter the stimulated aldosterone responses. Trifluoperazine (10(-6) M), an inhibitor of calmodulin, blocked AII and K+-induced aldosterone secretion, but was partially effective on ACTH-stimulated aldosterone output only at a concentration of 10(-5) M. The actions of ouabain on aldosterone biosynthesis were similarly affected by all these drugs. Thus, both extracellular Na+ and Ca2+ appear to play a role in the steroidogenic response of isolated glomerulosa cells. The intracellular action of Ca2+ may involve a calmodulin-like protein. The effects of ACTH are only partially dependent on Ca2+ as a second intracellular messenger.
Hypertension
PMID:Relative roles of sodium and calcium ions in the steroidogenic response of isolated rate adrenal glomerulosa cells. 627 6

Effects of CV-2619 (10 and 30 mg/kg/day, p.o.) or ubiquinone-10 (Q-10, 10 mg/kg/day, p.o.) treatment for 5 weeks on systolic blood pressure (SBP) and myocardial energy metabolism were studied in spontaneously hypertensive rats of 20 weeks of age. The systolic blood pressure was about 205 mmHg at the start of the experiment, and a slight increase was noted thereafter in the control (vehicle) group. CV-2619, but not Q-10, inhibited the increase in the blood pressure. At 25 weeks of age, cardiac hypertrophy was noted to the same extent in either treated group. Myocardial contents of glycolytic intermediates (glycogen, glucose, pyruvate and lactate) and creatine phosphate (Cr-P), ATP, ADP, and AMP were not significantly influenced by CV-2619 or Q-10 treatment. CV-2619, however, significantly increased the energy charge, an index of myocardial energy state, with higher dose and lowered the lactate/pyruvate ratio with either dose. These results suggest that CV-2619 has a mild antihypertensive effect and improves the myocardial energy state in the hypertrophied heart during the sustained phase of hypertension in SHR rats.
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PMID:[Effects of 2,3-dimethoxy-5-methyl-6-(10'-hydroxydecyl)-1,4-benzoquinone (CV-2619) on myocardial energy metabolism in the hypertrophied heart of spontaneously hypertensive rats]. 629 97


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