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

Two-kidney, one-clip Goldblatt models were produced in Wistar rats by placing a stenotic clip around the left renal artery. The animals were classified into three groups according to the time when captopril was started. In group 1 rats captopril was begun on the day following the operation and was continued for 6 weeks. During this period hypertension did not develop. In group 2 in which captopril was started 4 weeks after placement of the renal arterial clip, the blood pressure remained high as late as 12 weeks despite of continued administration of the drug. However, in group 3, captopril which was started 12 weeks postoperatively was very effective in correcting high blood pressure. In the sham operated group the blood pressure was unchanged by captopril administration. These results suggest that the role of renin-angiotensin system seems to vary according to the stages of experimental hypertension and that at least in the acute and chronic stage of two-kidney one-clip Goldblatt hypertension angiotensin II may play a major role in initiation and maintenance of high blood pressure.
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PMID:Study of renovascular hypertension in rat. II. Effects of converting enzyme inhibitor (captopril) in the acute and chronic stages of two-kidney one-clip Goldblatt hypertension in rat. 391 58

Rats were rendered hypertensive by clamping one renal artery. Both kidneys remained in situ ('two-kidney one-clip Goldblatt hypertension'). Half of the animals were simultaneously castrated. 18-24 weeks after the operation both castrated females and males had a lower level of hypertension than the uncastrated controls. The kidneys of castrates contained less connective tissue (measured as the content of hydroxyproline) and long-chain (C-18) fatty acids and had a higher specific activity of the enzyme N-acetylating p-aminohippurate (N-acetyltransferase) than those of uncastrated rats. Thus, castration seems to alleviate some renal effects of the Goldblatt hypertension. In all animals the clamped kidney contained more hydroxyproline and C-18 fatty acids and had a lower N-acetyltransferase activity than the contralateral untouched organ. These results are in accordance with the theory that renal fatty acid concentration interferes directly with the N-acetyltransferase activity of the kidney. The enhanced hydroxyproline content of the kidneys (nephrosclerosis) inhibits N-acetylation most probably indirectly by raising the tissue concentration of C-18 fatty acids.
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PMID:Effect of castration on the experimental renal hypertension of the rat. Blood pressure, nephrosclerosis, long-chain fatty acids, and N-acetylation of PAH in the kidney. 400 Mar 42

To study the influence of dietary modification of prostaglandin synthesis on blood pressure regulation, the effects of dietary enrichment with linoleic acid were compared with standard rat chow in three groups of 24 rats before and after renal artery constriction and contralateral nephrectomy. Dietary supplementation with 40 energy% sunflower seed oil or linseed oil respectively caused incorporation of linoleic or linolenic acids into tissue phospholipids. Relative to the sunflower seed oil, the linseed oil diet led to inhibition of prostanoid synthesis in kidney, serum or aorta in vitro and urine in vivo. Rats on both oil-rich diets had lower blood pressures than rats on a standard diet. Thus, partial suppression of prostaglandin synthesis did not accelerate one-kidney, one clip Goldblatt hypertension, nor did sunflower oil protect against hypertension in a way that could be specifically ascribed to changes in prostaglandin synthesis.
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PMID:Dissociation of effects of dietary fatty acids on blood pressure and prostanoid metabolism in Goldblatt hypertensive rats. 609 84

The urinary output of gamma-glutamyl-transpeptidase (gamma GT) and of N-acetyl-beta-D-glucosaminidase (NAG) was studied with "two-kidney Goldblatt hypertension' 3-6, 16-19 and 30-33 weeks after eliciting high blood pressure. gamma GT excretion rate of normotensive males was higher than that of females, while the activity of the renal tissue was on the same level. gamma GT output of hypertensive males was elevated in the early and in the middle stages of the disease, it was subnormal in the late stage. In females gamma GT output increased in animals with excessively high blood pressure (less than 200 mm Hg) only. gamma GT output correlated with the tissue activity in males only. In all animals there was an inverse, linear correlation between tissue gamma GT activity and the hydroxyproline content. The pattern of the NAG output was similar to that of gamma GT, however, excretion of NAG showed no sex differences and remained high in the late stage of the disease, too. Nephrosclerosis was less pronounced in female Goldblatt rats than in males.
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PMID:Enzymuria (the output of gamma-glutamyl-transpeptidase and of N-acetyl-beta-D-glucosaminidase) in the course of experimental renovascular hypertension. 611 50

The effect of castration of male rats with experimental renal hypertension ('two-kidney Goldblatt hypertension') was studied on the height of the hypertension and on the urinary output of gamma-glutamyl transpeptidase (gamma GT) and of N-acetyl-beta-D-glucosaminidase (NAG). Castration was carried out immediately after clamping one renal artery. Some of the castrates received testosterone substitution from the 3rd postoperative week onwards. Uncastrated hypertensive males served as controls. The experiments were carried out 8-18 weeks after eliciting high blood pressure. Hypertension as well as enzymuria were less expressed in castrates than in uncastrated males or in testosterone-substituted rats. In all animals studied the gamma GT excretion rate showed a positive correlation with the blood pressure. The output of gamma GT and of NAG as well as the specific gamma GT activity of the renal membrane fraction was lower in castrates than in uncastrated males or in substituted castrates. In uncastrated males and in testosterone-substituted castrates the daily NAG output showed a direct correlation with the renal hydroxyproline content. No such correlation was found in castrated males. The kidneys of castrates and of testosterone-substituted castrates contained less hydroxyproline than those of uncastrated males.
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PMID:Effect of castration and testosterone substitution on the urinary output of gamma-glutamyl transpeptidase and of N-acetyl-beta-D-glucosaminidase of male rats with renovascular hypertension. 613 47

The activities of the catecholamine synthesizing enzymes have been determined in discrete brain areas and in peripheral tissues of rats, at different times after clipping the left renal artery (two-kidney Goldblatt hypertension, 2KGH) and in sham operated animals. Three days after clipping the only enzymatic change was a slight decrease in plasma dopamine-beta-hydroxylase (DBH) activity. Ten days after clipping no change in enzymatic activity was found at the central level. However, the DBH and the phenylethanolamine-N-methyltransferase (PNMT) activities were increased in the adrenal medulla (+49.0%, P less than 0.001 and +36.6%, P less than 0.001, respectively) and DBH activity was also increased in the superior cervical ganglia (+22.8%, P less than 0.01). These data suggest that sympathetic hyperactivity is present in 2KGH rats when hypertension is established. In addition, as this type of hypertension does not alter the PNMT activity in brainstem areas, it seems that the alterations in PNMT activity reported for genetically hypertensive rats are unlikely to be secondary to the elevated blood pressure.
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PMID:Central and peripheral catecholamine synthesizing enzymes during the development of two-kidney, one clip hypertension in rats. 615 68

The renal microcirculation was assessed in non-clipped kidneys of 23 Munich-Wistar rats with two-kidney one-clip Goldblatt hypertension. Four weeks after placement of a renal arterial clip, mean systemic arterial pressure averaged 163 +/- 5 mm Hg in hypertensive rats as compared to 108 +/- 2 in sham-operated controls (n = 6 rats). Non-clipped kidneys in hypertensive rats were characterized by higher glomerular capillary hydraulic pressures, single nephron glomerular filtration rate, and afferent arteriolar resistance. The glomerular capillary ultrafiltration coefficient was significantly reduced in hypertensive rats. In 10 of these rats, intravenous infusion of the angiotensin antagonist, saralasin, or the converting enzyme inhibitor, SQ20881, led to significant reductions in systemic arterial pressure and in afferent and efferent arteriolar resistance, on average by 8 +/- 3%, 15 +/- 4%, 28 +/- 5%, respectively. These changes were associated with significant increase in glomerular plasma flow, while ultrafiltration coefficient remained unaffected. In the presence of saralasin or SQ20881, infusion of a specific antagonist of the vascular action of arginine vasopressin led to significant systemic but not renal vasodilation. Thus, whereas systemic arterial pressure fell further, on average by 23 +/- 2%, renal arteriolar resistance remained constant, resulting in marked reduction in glomerular capillary hydraulic pressures (by 18 +/- 2%) and glomerular plasma flow rate (by 28 +/- 10%). Because of these pronounced reductions in glomerular pressures and flows induced by vasopressin antagonist, single nephron glomerular filtration rate fell markedly in hypertensive rats (by 34 +/- 6%) despite normalization of ultrafiltration coefficient. When hypertensive rats (n = 7) were treated with vasopressin antagonist alone, a modest fall in systemic arterial pressure was again observed in the absence of changes in renal arteriolar resistance. Due to this selective extrarenal vasodilatory action of vasopressin antagonist, glomerular capillary hydraulic pressure, plasma flow rate, and single nephron glomerular filtration rate again fell markedly. When these vasopressin antagonist pre-treated hypertensive rats were given saralasin or SQ20881, marked reductions in renal arteriolar resistance were observed in association with a significant increase in glomerular plasma flow rate. These observations made during acute inhibition of angiotensin II and vasopressin indicate that both of these vasopressin hormones may play important roles in maintaining systemic hypertension in hypertensive rat. By virtue of its preferential constrictor effects on extrarenal rather than renal vasculature vasopressin serves to maintain high glomerular pressures and flows in the non-clipped kidney of Goldblatt hypertensive rats.
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PMID:Relative contribution of vasopressin and angiotensin II to the altered renal microcirculatory dynamics in two-kidney Goldblatt hypertension. 619 14

The development of two-kidney, two clip Goldblatt hypertension (2K2C) in the rat seems to be unaffected by chemical sympathectomy with 6-hydroxydopamine (6-HODA) and adrenal demedullation. Since this treatment only partially depletes vascular norepinephrine (NE) content, we evaluated the degree of sympathectomy achieved with the 6-HODA treatment and the structural vascular changes in treated and untreated animals. Litters of male Wistar rats were divided in two groups: 6-HODA-treated (6-HODA) animals (group 1) were injected with 6-HODA since the day of birth until the end of the experiment; control group (CG) animals (group 2) received the vehicle solution. When rats reached about 250 g, a silver clip (0.25 mm width) was placed on both renal arteries in half of them in each group; a sham operation was performed on the rest of the animals. Adrenal demedullation and denervation was performed in all 6-HODA animals. Blood pressure was followed weekly by the tail cuff method for 7 weeks. At the 8th week, Silastic cannulas were placed in the carotid artery and jugular vein in all the animals. Pressor responses to tyramine (0.05 and 0.1 mg), angiotensin (10, 40 and 160 ng), and norepinephrine (NE) (25, 100 and 400 ng) and the hypotensive effect of prazosin (1 mg/kg) were determined in the conscious rats. The pressor effect of carotid occlusion was registered 24 hours later. Animals were sacrificed, and the heart and artery weight as well as the nucleic acids and alkali soluble proteins content in the vascular wall were determined.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension
PMID:Further studies on the development of two-kidney, two clip Goldblatt hypertension in 6-hydroxydopamine-treated rats. 619 76

The renal arteriogram alone, useful as an anatomic guide for the surgeon or radiologist, is inadequate to predict potential blood pressure reversal by correction of the obstructing lesion. A patient must be identified as having functionally significant renal arterial disease before intervention can be recommended. The authors discuss uncovering functionally significant renal artery stenosis, the pathophysiology of experimental Goldblatt hypertension, and criteria to identify renovascular hypertension, including peripheral plasma renin activity and differential renal-vein renin determinations.
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PMID:Clinical evaluation of renovascular hypertension and therapeutic decisions. 620 95

An endogenous, immunoreactive digoxin-like factor (endoxin) was measured in the plasma of nonhuman primates with hypertension. Both normotensive and hypertensive rhesus monkeys had levels of endoxin that significantly correlated with their systolic or diastolic blood pressure. Vervet monkeys with experimentally produced chronic Goldblatt hypertension had significantly elevated endoxin, but not plasma renin. These data suggest that increased plasma endoxin may be a contributing factor in the development of hypertension.
Hypertension
PMID:Increased circulating levels of an endogenous digoxin-like factor in hypertensive monkeys. 627 95


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