ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The activity of protein kinase C and A was studied in the erythrocytes of patients with essential hypertension (EH) and in spontaneously hypertensive rats (SHR, Okamoto—Aoki strain). Protein kinase C activity was also studied in the erythrocytes of patients with hypertension of renal origin.Protein kinase C activity in the lysate of erythrocytes of patients with EH and in SHR was found to be increased 1.6–2.0-fold as compared to that in normotensive controls. No notable differences in protein kinase A activity were observed between hypertensive and normotensive groups. In erythrocytes of patients with renal hypertension, no notable changes in protein kinase C activity were revealed.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Fifty untreated male patients aged 32 ± 10 (s.d.) years, referred for hypertension, in whom organ damage was limited to WHO stages I and II, without underlying disease, performed a graded, uninterrupted exercise on a bicycle ergometer up to exhaustion. Mean brachial intra-arterial pressure at rest ranged from 74 to 152mmHg. Maximal voluntary oxygen uptake was independently and negatively related to resting blood pressure (P<0.05), age (P=0.05), and positively to body weight (P<0.05). Pulmonary wedge pressure and the components of the Fick equation — heart rate, stroke volume and arteriovenous oxygen difference — were measured in order to study the mechanisms involved. Stroke volume at peak exercise was inversely (P<0.05), and pulmonary wedge pressure positively (P<0.01), related to mean brachial artery pressure at rest. Peak heart rate was not significantly related to the severity of hypertension, but was inversely related to age (P<0.01). Stroke volume and pulmonary wedge pressure at the end of exercise were both similar in older and younger patients. Arteriovenous oxygen difference at peak exercise was not related either to blood pressure or to age.In conclusion, both high blood pressure and age reduce maximal voluntary oxygen uptake independently of each other by separate mechanisms; the former by an impairment of cardiac function, the latter by the limitation of peak heart rate.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

To examine a possible role of endogenous bradykinin in the regulation of blood pressure (BP) and renal blood flow (RBF), a newly synthesized competitive antagonist of bradykinin (B4147) was studied in anesthetized rats. Also, the question of whether the hypotensive effect of the converting enzyme inhibitor, captopril, is mediated partly by an accumulation of endogenous bradykinin was considered. The intravenous infusion of B4147 (25µg/min) inhibited the depressor effect of exogenous bradykinin (0.5 µg, i.v.) by 69%. After an intravenous injection of B4147 at doses of 25, 50 and 100 µg, BP increased and RBF decreased in a dose-dependent fashion. The increase in BP was not blocked by pretreatment with an angiotensin II antagonist (1-Sar-8-IIe angiotensin II; 20 µg/kg per min) or an α1-blocker (prazosin; 0.1 mg/kg). The administration of captopril (1 mg/kg) decreased mean BP from 110 ± 3.5 to 71 ± 1.9mmHg (P<0.001). However, the injection of B4147 (50 µg) after the administration of captopril elicited an increase in BP of 43% of the initial decrease induced by captopril. These results suggest that the effects of B4147 on BP and RBF are not mediated through angiotensin II or sympathetic α1stimulation. Endogenous bradykinin could contribute to the maintenance of BP and RBF in anesthetized rats, probably counterbalancing the vasoconstrictor mechanisms. It is also suggested that bradykinin may partly participate in the acute hypotensive effect induced by the converting enzyme inhibitor captopril.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

A decrease in platelet 5-HT content linked to partial inhibition of 5-HT uptake has been described in essential hypertension. Transport of 5-HT through platelet membrane is dependent upon transmembranal Na+and K+gradients. It is inhibited by Na+,K+-ATPase inhibitors such as ouabain and endogenous digitalis-like compounds isolated from hemodiafiltrate. The activity of such compounds in plasma extracts, measured by inhibition of Na+,K+-ATPase or ouabain binding to human erythrocytes, and platelet 5-HT content were determined in parallel in essential hypertensive patients. Significant negative correlations were observed between these parameters in men, suggesting that high levels of digitalis-like compounds can affect platelet 5-HT content.In addition, in essential hypertensive patients, total plasma cholesterol was inversely related to both platelet 5-HT content (n = 15, r = −0.594,P<0.02) and maximal velocity of 5-HT uptake (n = 15, r = −0.717,P<0.003). In normotensive control subjects, no variation of platelet 5-HT content with cholesterol was observed. This suggests that the platelet membranes of essential hypertensive patients are more sensitive to increases in plasma cholesterol than those of normotensive subjects.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Calcitonin gene-related peptide (CGRP) is localized in nerve fibres in close association with the vasculature. Thein vivoeffect of human CGRP upon the cardiovascular system was investigated by intravenous infusion of CGRP into seven conscious sheep at doses of 1, 5 and 10-pmol/kg per min for 75 min. CGRP at the 5-and 10-pmol/kg per min infusions decreased mean arterial pressure (maximal decrease of 10 mmHg) and stroke volume maximal decrease of 42 ml/min), and increased heart rate by 60 beats/min. No changes in cardiac output were observed and total peripheral resistance only fell with the 5-pmol/kg per min infusion. Increases in both plasma arginine vasopressin and plasma renin concentration and a decrease in total and ionized plasma calcium were also observed. CGRP appears to be a potent vasodilator acting upon both arterioles and capacitance vesselsin vivo.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Since hypertension is associated with changes in the handling of various cations (including sodium and lithium) across the cell membrane, the present study investigated the validity of the lithium clearance method in hypertension by comparing two measures of proximal reabsorption. Thus, fractional lithium excretion and transit time (TT)-occulsion time (OT; e−TT/OT) were determined successively in the same spontaneously hypertensive rat (SHR, Okamoto strain). The rats were examined both before and after an acute saline load.The results show that the lithium clearance method can be used for the determination of proximal reabsorption in SHR. Utilizing the lithium clearance method, the changes in renal sodium handling underlying the exaggerated natriuresis were investigated in unanaesthetized catheterized rats. It was found that the exaggerated natriuresis was associated with an increased output from the proximal tubule, whereas no difference in distal sodium handling could be detected between SHR and normotensive Wistar-Kyoto rats (WKY).

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The haemodynamic impact of α- and β-adrenoceptor blockade (labetalol) was compared with that of slow-calcium channel blockade (nifedipine) in 32 patients with sustained elevation of systemic arterial pressure (systolic blood pressure>160; diastolic blood pressure>95 mmHg) following a recent myocardial infarction (6-22 h). Patients with normal (pulmonary artery occluded pressure; PAOP<18 mmHg; n=16) or impaired (PAOP>18mmHg; n=16) left ventricular function were randomized to labetalol (1 mg/kg i.v. 15 min) or nifedipine (20 mg sublingually) and haemodynamic profile was measured over 2h.Both drugs equally reduced mean systemic arterial pressure (P<0.01 versus pretreatment control), and presumably left ventricular afterload; however, the heart rate (P<0.01) and cardiac index (P<0.01) increased after nifedipine, contrasting with reductions in both variables following labetalol (P<0.01). The elevated left ventricular filling pressure was reduced by both labetalol (P<0.05) and nifedipine (P<0.01) but the reduction was greater following nifedipine ( — 2mmHg versus — 5mmHg,P<0.05). Thus both compounds were equally effective hypotensive agents. Labetalol consistently reduced cardiac stroke work and double product, important determinants of myocardial oxygen requirements; however, nifedipine afforded some improvement in cardiac performance in patients with left ventricular dysfunction.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

This paper reports an investigation of blood pressure (taken as a continuous variable) as a function of: erythrocyte Na+content; Na+, K+pump; Na+, K+cotransport and Na+, Li+countertransport fluxes, and passive cation permeabilities in fresh erythrocytes from 129 French males who were living in an urban area and were not under treatment for any medical condition (after allowing for the effects of age, body mass index, alcohol and tobacco consumption).In contrast with previous findings in a North American population [1], we were unable to confirm that blood pressure was correlated with erythrocyte Na+content and Na+, K+-ATPase activity. Conversely, the only transport parameter correlated (negatively) with blood pressure was outward Na+, K+cotransport [r=-0.20,P<0.05 andr=-0.19,P<0.05, for systolic (SAP) and diastolic arterial pressure (DAP), respectively; n=114]. When allowing for age, body mass index and alcohol consumption, the correlation coefficient between the Na+, K+cotransport system and blood pressure increased from -0.20 to -0.28 (P<0.01) for SAP and from -0.19 to -0.28 (P<0.01) for DAP (n=105).We conclude that the correlations between blood pressure and erythrocyte Na+transport function could differ between North American and French (or Mediterranean) populations. In any case, a decreased pump or outward Na+, K+cotransport activity may lead hypertensive subjects to a similar increase in cell Na+(and Ca2+) content in the vascular wall.

ISSN:0263-6352    

出版商:OVID    

年代:1988

数据来源: OVID