ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The norepinephrine- (50, 100 and 200 ng/kg per min) induced rise in blood pressure (BP) was determined in six healthy male volunteers following angiotensin converting enzyme (ACE) inhibition by either captopril (100 mg orally) or HOE 498 (10 mg orally). In terms of absolute BP measurements both compounds induced a reduction in basal and norepinephrine stimulated BP, whereas norepinephrine induced increments of BP above individual basal levels were unchanged by either converting enzyme inhibitor. It is concluded that attenuation of the pressor response to norepinephrine does not contribute to the hypotensive action of ACE inhibitors in healthy man.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To assess possible relationships between sodium balance, angiotensin II (ANG II), and renal active and inactive kallikrein, we studied the effects of sodium loading with 1 % NaCl and chronic ANG II infusion (900 µg/kg per day) on the urinary excretion of total and active kallikrein for 6 days in conscious rats. We determined urinary total, active and inactive kallikrein by measuring kallikrein activity using a kininogenase assay before and after treatment with trypsin (200 µg/ml). Sodium loading produced a sustained increase in urinary total, active and inactive kallikrein excretion. Chronic infusion of ANG II induced a sustained increase in urinary total, active and inactive kallikrein excretion in rats on a regular diet. In rats loaded with sodium, however, ANG II did not induce any further changes in urinary kallikrein excretion. Thus, the present study suggests that both sodium loading and ANG II infusion might stimulate the synthesis of renal kallikrein. In addition, it is suggested that ANG II infusion might stimulate the synthesis of kallikrein, at least partly, via the same mechanism as sodium loading does.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Abnormal calcium (Ca) homeostasis has been reported in essential hypertension and in the Okamoto-Aoki strain of spontaneously hypertensive rats. These abnormalities include increased urinary excretion of calcium and decreased ionized serum calcium (Ca2+). To pursue these abnormalities we studied the chronology of urinary excretion of electrolytes in a genetically homogeneous strain of hypertensive rat, the Dahl/Rapp salt sensitive (S) and resistant (R) rat (at ages 3, 5, 7, 9, 12, 20 and 32 weeks). We also characterized the renal adenylate cyclase-cAMP, system by measuring urinary cAMP excretion and adenylate cyclase response to membrane receptor agonists in renal membranes from S and R rats at day 2 and at 6 and 28 weeks of age. Urinary calcium excretion was higher in S than in R at 3, 5 and 7 weeks (0.48 ± 0.04 versus 0.24 ± 0.01 mg/mg creatinine at 7 weeks,P<0.01). Sodium and phosphorous excretion were lower in S than in R rats at 5, 7, 9, and 12 weeks, and at 5, 7, 9, 12, 20 and 32 weeks, respectively. Potassium excretion was similar in the two groups. Plasma ionized calcium was lower in S than in R rats (3.9 ± 0.1 versus 4.5 ± 0.1 mg/dl, P<0.01) only at 7 weeks of age. Plasma parathyroid hormone (PTH) was not different between S and R rats. Cyclic AMP excretion and the renal adenylate cyclase response to PTH when referenced to basal activity was lower in S than in R rats at all ages. These studies demonstrate that in the Dahl S rats, there is increased urinary calcium excretion and decreased urinary cAMP excretion associated with decreased adenylate cyclase response to PTH in the kidney. This decreased adenylate cyclase response to PTH may be a causal factor in the increased urinary calcium in Dahl S rats. The relationship between altered calcium homeostasis and the hypertension mechanism is unknown.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effect of intravenous (i.v.) captopril on mean arterial blood pressure (MABP) of anaesthetized normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats perfused i.v. with two doses of angiotensin II (ANG II; 2.9 and 5.8 pmol/kg per min) was studied to determine the role of the suppression of plasma ANG II in the hypotensive action of captopril. The reduction of MABP by captopril was attenuated in WKY and abolished in SHR by the highest dose of ANG II; it was unchanged in WKY and attenuated in SHR by the lowest dose of ANG II. The suppression of plasma ANG II thus explains a minor part of the acute reduction of MABP by captopril in WKY and a major part of this action in SHR. Plasma ANG II contributes to the maintenance of high blood pressure in SHR.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

There is controversy about the effects of dietary sodium deprivation on cellular cation transport. Using washed erythrocytes forin vitro22Na and86Rb uptake studies, we studied the effects of a strict low-salt diet (20 mmol/day) for 4 days in 14 normotensive and 13 hypertensive subjects. Urinary sodium excretion fell from 147 ± 13 to 18 ± 3 mmol/24 h in the normotensive group and from 155 ± 16 to 20 ± 2 mmol/24 h in the hypertensive group. In both groups, there was a fall in plasma sodium concentration and activation of the renin-aldosterone axis. Both systolic and diastolic blood pressures fell in the hypertensive, but not the normotensive group. There were small but significant (P<0.025) decreases in cell cation concentrations and passive cation transport in the normotensive, but not the hypertensive group. No significant change in sodium pump activity or in Na+K+cotransport was seen in either group. These observations provide no support for the concept that a decrease in dietary sodium intake can induce changes in cell cation transport, detectablein vitro, to which reduction in blood pressure may be attributed.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Eight healthy volunteers received both oral enalapril (EN; MK-421) 20 mg and placebo (PL) under stable conditions of sodium repletion, 300 mmol sodium/day (HS) and sodium depletion, 10 mmol sodium/day (LS). During PL therapy, fivefold increases in the plasma concentrations of renin and aldosterone were observed when measurements under LS were compared with those under HS conditions. Basal blood pressure (BP) readings were consistently higher and the hypotensive response to EN greater under LS compared with HS conditions. After EN, renal plasma flow increased significantly over the first 4 h, while the glomerular filtration rate, measured both by inulin and creatinine clearances, did not change. A significant natriuretic response was observed within 2 h; further natriuresis between 6 and 12 h after EN was accompanied by increased phosphate excretion.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Subcellular membrane fractions were isolated from mesenteric arteries and vas deferens of salt-resistant and salt-sensitive Dahl rats on low-salt (0.4% NaCl) and high-salt (8.0% NaCl) diets. Only the salt-sensitive Dahl rats on the high-salt diet developed sustained high blood pressure (BP) after 5 weeks of the high-salt diet. Protein contents, membrane associated enzyme activities, calcium ion (Ca2+) binding and ATP-dependent Ca2+transport were compared in fractions isolated from all four groups. No obvious changes were observed, except for minor enhancement in magnesium ion (Mg2+)- and Ca2+ATPase activities of mesenteric arterial membranes isolated from salt-sensitive Dahl rats on high-salt diet compared to those from other groups of rats. The membrane fractions from vas deferens of salt-sensitive Dahl rats on the high-salt diet, on the other hand, showed decreased ATP-dependent Ca2+transport compared to those from salt-sensitive Dahl rats on the low-salt diet. No difference was observed in membrane fractions isolated from salt-resistant Dahl rats on high-salt diet compared to those on low-salt diet. The significance of these observations are discussed in relation to the findings previously obtained from corresponding smooth muscle tissues of spontaneous hypertensive rats (SHR).

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To define the role of the renal dopaminergic system in the pathogenesis of essential hypertension, urinary free dopamine excretion was examined 23 normotensive subjects who had one or more first-degree relatives with essential hypertension, and also in 36 matched control subjects without any such family history. The group urinary dopamine excretion and urinary sodium excretion were not different. However, a significant urine dopamine-sodium relationship was apparent in the controls but not in the relatives due to relatively high dopamine output in those with lower sodium excretion. The two groups were similar as regards blood pressure(BP), plasma renin activity (PRA), prolactin and catecholamines. These findings demonstrate an alteration in the urine dopamine-sodium relationship in some normotensive subjects with genetic risk of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Potassium chloride (KCl) salt (65 mmol) daily reduced BP from 153/104 to 146/101 mmHg in 32 hypertensive black females during a 6-week placebo controlled crossover study. The fall in BP was independent of the order of randomization and as significant for systolic (SBP; P<0.01) and diastolic (DBP; P<0.05) pressure after 4 weeks. Analysis of the 95% confidence intervals in this and in five other studies, two of which were reported as showing no beneficial effect, suggests that potassium supplementation does lower BP, but that the change is small and within the confidence levels of all six trials. Thus, apparent discrepancies in the literature are not genuine statistically.

ISSN:0263-6352    

出版商:OVID    

年代:1986

数据来源: OVID