ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Using hybridization histochemistry, a technique which localizes specific mRNA populations in tissue sections with a 700 base pair recombinant DNA probe which codes for ovine renin, we have localized renin gene expression in the afferent arteriole of the juxtaglomerular apparatus (JGA) in the sheep renal cortex. Specific labelling representing renin gene expression was also found at a distance from the glòmerular tuft in the walls of the afferent arteriole and also in cells in the medial layer of larger vessels of the renal cortex, specifically the interlobular arteries. These observations provide morphological evidence of renin gene expression at these sites and, combined with ultrastructural and immunocytochemical evidence suggest that renin is synthesized and stored in the afferent arteriole either within the JGA or at a distance from the glomerulus, and in the smooth muscle coat of the interlobular arteries in the sheep kidney.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

H.261, a new transition state inhibitor of human renin with an IC50of 6.9 x 10-10M, was given by intravenous infusion to six anaesthetized baboons. The inhibitor was infused first at 0.1 (µmol/kg/h for 15 min, then at 1.0 µmol/kg/h for a further 15 min. After a recovery period of 2 h in which the animals received 5% dextrose, they were infused with captopril, 25 µmol/kg/h for 15 min. At both rates of infusion H.261 markedly and significantly reduced the enzymatic action of renin in plasma, the blood concentration of angiotensin I, the plasma concentration of angiotensin II and mean arterial pressure. All changes reverted towards or to control values in the subsequent control period. Captopril also lowered plasma angiotensin II concentration and mean arterial pressure markedly and significantly but, as expected for an inhibitor of the angiotensin l-converting enzyme, plasma active renin concentration and blood angiotensin I concentration increased. The changes of angiotensin II and arterial pressure were similar with captopril and H.261

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

A 68-year-old man with a nine-year history of licorice ingestion had moderate hypertension and low plasma potassium. Exchangeable sodium and blood volume were increased to 128 and 111%, respectively of the expected values; plasma renin and aldosterone levels were suppressed. Plasma norepinephrine concentration was distinctly elevated but the pressor response to infused norepinephrine was normal. After licorice withdrawal, blood pressure, plasma potassium and blood volume reverted to normal levels within three weeks, exchangeable sodium and plasma renin within four months. Exchangeable sodium in our patient with licorice-induced hypertension was increased to a comparable extent as in primary hyperaldosteronism. Moreover, blood pressure in relation to body sodium or plasma potassium did not differ between the exogenous or the endogenous types of mineralocorticoid excess. This observation does not support the possibility that in primary hyperaldosteronism excess aldosterone secretion per se could play an important pressor role independently from sodium retention.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The metabolism of phosphoinositides, a class of membrane lipids involved in Ca2+-transport and/or mobilization systems, was investigated in patients with moderate essential hypertension and in Sabra rats. Experiments were performedin vitroon isolated erythrocyte membranes by measuring the32P-labelling of phosphatidylinositol 4,5-bisphosphate (Pl-P2) and of phosphatidylinositol 4-phosphate (Pl-P) following the incubation of membranes with [γ -32P] ATP. In untreated essential hypertensives (n=31) or in hypertensive patients whose blood pressure was controlled by beta-blocker therapy (n=20),32P-Pl-P2 was significantly higher than in normotensive controls (n=30); no significant difference was observed between the two groups of hypertensive patients. In Sabra rats fed on a low Na diet,32P-Pl-P2 levels were significantly higher in hypertensive-prone animals (SBH) than in hypertensive-resistant animals (SBN). When the animals were fed a high Na diet or were DOCA/ salt treated,32P-Pl-P2 did not change in either substrain, although such conditions differentially affected the blood pressure of SBH and SBN. Our data indicate that the modification of phosphoinositide metabolism is not a consequence of the blood pressure elevation, but can be considered as an intrinsic membrane defect which may be associated with functional alterations of Ca2+fluxes which in hypertensives result in an enhanced intracellular Ca2+level.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

Normotensives with hypertensive parents have been reported to exhibit enhanced cardiovascular reactions to mental stress. We have examined the question of why this result was not confirmed in all studies. In addition we have investigated whether appropriate tests can be performed under clinical rather than laboratory conditions.Healthy male subjects were examined. In experiment I, under laboratory conditions, a standard stress test was intensified (n=30). In experiment II the same test was used in a simplified version which did not require special equipment (n=19). Blood pressure, heart rate and stroke volume (by impedance cardiography) were measured.In contrast to the results with the standard test, subjects with at least one hypertensive parent exhibited enhanced responses of systolic and diastolic blood pressure and heart rate.We conclude that cardiovascular hyper-reactivity in subjects with hypertensive parents is only apparent using sufficiently intense stimuli. Although less pronounced, these differences can also be observed under clinical conditions.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

We have examined the mechanisms mediating the release of renin elicited in man by reduction of renal perfusion pressure. Fifteen patients with essential hypertension and six normotensive subjects were investigated during diagnostic renal arteriography. Renal neural receptors were inhibited by propranolol (10 mg i.v.) and activated by a standard cold pressor test. Vascular receptors were stimulated by unilateral reduction of renal perfusion pressure by 50%, using a balloon-tipped catheter.The stimulus caused release of renin. In hypertensives, arterial plasma renin increased by 44, 69 and 73% of control at 5, 15 and 30 min, respectively. Adrenergic activation by cold raised the arterial and the renal venous renin by approximately 50% of control and caused a fourfold rise when it was combined with the arterial obstruction. Following propranolol the renin response to reduction of the renal perfusion pressure was delayed and reduced, and cold stimulation, both alone and in combination with arterial obstruction, failed to stimulate renin release. Findings were qualitatively and quantitatively similar in the normotensive group.This study supports the hypothesis that the renin response to reduction of renal perfusion pressure in man results from an interaction of adrenergic and vascular receptors. It cannot be stated whether the former are synergistic or supplementary to the latter, even though adrenergic activation by cold stimulation provides evidence that a synergism between the two may exist.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

The effects of enalapril maleate and its lysine analogue, lisinopril, on reflex control of heart rate after acute and chronic administration were examined in 10 normotensive males. Both drugs reduced blood pressure without change in heart rate after acute dosing and after seven days. Both drugs impaired the vagally mediated early cardiac acceleration associated with lying down (standing to lying test). A similar effect was observed following edrophonium. After lisinopril bradycardia induced by facial immersion (diving reflex) was significantly attenuated. Edrophonium similarly attenuated the bradycardia. Both these reflexes are parasympathetically mediated. Neither drug altered heart rate or blood pressure changes following Valsalva's manoeuvre and the cold pressor test. Plasma noradrenaline was unchanged. Absence of reflex tachycardia with blood pressure reduction by converting enzyme inhibitors may be related to increased parasympathetic activity either centrally or peripherally wihout impairment of baroreflexes or sympathetic function.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To assess whether and how the activation of the renin-angiotensin system that occurs in response to changes in posture contributes to the maintenance of blood pressure, we measured blood pressure, heart rate, plasma noradrenaline and plasma active and inactive renin in patients with essential hypertension in the supine, sitting and standing positions, (each sustained for 30 min), before and after administration of captopril. These studies were performed before and after a brief period of diuretic therapy. Both in the normal and in the sodium depleted state captopril reduced the normal adaptive response of blood pressure to changes in body position, whereas the responses of heart rate and plasma noradrenaline to these stimuli were unaffected by captopril. In contrast, the postural increases in active renin were magnified after captopril while inactive renin was unchanged throughout these acute studies. Our results indicate that during mild but rather prolonged postural stresses the generation of angiotensin by active renin supports blood pressure either through its direct vasoconstrictive effect and/or by potentiating the activity of the sympathetic nervous system. It is unlikely that the changes in active renin depend upon conversion from the inactive form.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID

摘要:

To investigate the regulation of sympathetic-adrenal medullary function in spontaneously hypertensive (SHR) male rats, we measured urinary catecholamine excretion for 4 h at room temperature and also during cold exposure (4°C) in groups of four and 12-week-old stroke-prone SHR (SHRSP), stroke-resistent SHR (SHRSR) and normotensive Wistar-Kyoto (WKY) rats. The effect of cold exposure on 12-week-old adrenal denervated rats was also examined. At room temperature, urinary excretion of epinephrine, but not norepinephrine or dopamine, was increased significantly in four-week-old SHRSP and SHRSR rats compared with age-matched WKY. The enhanced excretion of epinephrine at room temperature was not observed in hypertensive rats at 12 weeks of age. During cold exposure, urinary concentrations of each catecholamine increased markedly in rats of all three strains. In addition, the epinephrine response was significantly enhanced in SHRSP rats and the norepinephrine, epinephrine and dopamine responses were significantly enhanced in SHRSR rats. Following adrenal denervation, the urinary epinephrine response to cold exposure was abolished in all strains. These results reveal an enhancement of sympathetic and neurally-mediated adrenal medullary responses in prehypertensive SHR rats and a greater urinary epinephrine response to cold exposure in four and 12-week-old SHR rats. This alteration in catecholamine secretion may be important in the development and maintenance of this type of experimental hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1985

数据来源: OVID