ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To our knowledge, there have been no published comparisons of different techniques for measuring blood pressure during clinical trials. We undertook a comparison during clinical trials with verapamil and prazosin. During an open trial of verapamil we compared the treatment-induced blood pressure reductions as measured by clinic, intra-arterial, and self-recorded methods. The mean reduction in blood pressure was 38 ± 13.6/20 ± 10.1 mm Hg for clinic blood pressure, 24 ± 17.9/16 ± 7.3 mm Hg for self-recorded blood pressure, and 23 ± 12.3/19 ± 10.1 mm Hg for mean daytime intra-arterial blood pressure. During prazosin treatment the mean reduction in blood pressure was 28 ± 21.5/18 ± 8.5 mm Hg for clinic blood pressure, 21 ± 20.5/6 ± 13.7 mm Hg for self-recorded blood pressure, and 18 ± 19.2/5 ± 9.6 mm Hg for mean daytime intra-arterial blood pressure. There was little agreement between methods within individual patients and for group comparisons of intraarterial or clinic methods. There was, however, good agreement between intra-arterial and selfrecorded methods. This study suggests that self-recorded blood pressure recording is suitable for monitoring efficacy of antihypertensive agents in a group of patients, although caution must be exercised when interpreting the effects of therapy when measured by indirect methods in an individual patient.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The effect of short-term diuretic treatment on the action of clonidine was evaluated in eight subjects with mild, uncomplicated hypertension. A single oral dose of clonidine (0.3 mg) was given before and after 1 week of therapy with hydrochlorothiazide, 50 mg, and amiloride, 5 mg, taken daily. Changes in mean arterial pressure, heart rate, plasma norepinephrine and epinephrine levels, and plasma renin activity were assessed. Diuretic treatment caused a significant weight loss, increased plasma renin activity, and reduced serum potassium concentration but did not significantly alter the absolute reduction in mean arterial pressure caused by clonidine. Absolute clonidine-induced reduction in plasma renin activity after diuretic treatment was three times greater than before treatment, although percent changes were similar. Before diuretic therapy, clonidine significantly reduced the level of norepinephrine (absolute and percent change). After diuretic treatment, clonidine failed to suppress norepinephrine, and the difference from prediuretic changes was significant. The level of epinephrine was not altered significantly either by diuretic treatment or clonidine. These results indicate that diuretic therapy alters the clonidine-activated mechanism for reduction of arterial pressure through a shift from overall suppression of sympathetic tone to pathways that are more restricted to renal tone. This shift may be due to changes in fluid or electrolyte balance that alter the action of aradrenergic receptor-mediated pathways. Use of the clonidine suppression test for the diagnosis of pheochromocytoma may give false-positive results in diuretic-treated patients.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Several significant interrelations among variation in blood pressure, body fat, and adrenal androgen levels, as assessed by serum dehydroepiandrosterone sulfate concentrations, were found in black male and female adolescents, aged 12 to 16 years. In girls, high levels of dehydroepiandrosterone sulfate were associated with significantly higher levels of blood pressure (a = 0.05), even after adjusting for the significant association between increased levels of dehydroepiandrosterone sulfate and body fat. The increased body fat (i.e., body mass index) found with higher levels of dehydroepiandrosterone sulfate in girls was related to significantly greater (a = 0.05) accumulations of fat in the upper trunk, as opposed to the limb. In boys, high levels of serum dehydroepiandrosterone sulfate, low body mass index, and significantly higher blood pressure were interrelated (a = 0.05). In addition to the interaction of increased body mass index or body fat and increased levels of dehydroepiandrosterone sulfate in association with higher blood pressure, high levels of the adrenal androgen, even in boys with low body mass index, were associated independently with relatively higher blood pressure. Body proportion analyses for these boys indicated that they were tall and thin, in contrast to the other boys with low body mass index, who were generally short and thin.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

An outpatient diagnostic procedure measuring the 6-hour integrated plasma concentration of aldosterone and plasma renin activity was used to detect primary aldosteronism in 12 patients with low renin hypertension, including six with mild hypertension and normal urinary excretion and spot plasma levels of aldosterone. The ratio of integrated plasma concentration of aldosterone to plasma renin activity in the 12 patients (mean, 339; range, 116–700;p< 0.0001) did not overlap with that measured in 105 normotensive controls (mean, 27.8; range, 5–97) or in 87 subjects with essential hypertension (mean, 29.2; range, 4–67). Eight patients had surgically proven adenomas (3 of which measured <5 mm) with normalization of blood pressure following adrenalectomy. The four remaining patients had bilateral hyperplasia. The 6-hour integrated plasma concentration of aldosterone to plasma renin activity ratio was found to be a useful new outpatient diagnostic tool for evaluation of primary hyperaldosteronism.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Thirteen patients were entered into a protocol to assess the safety and efficacy of enalapril (MK 421), 5 to 20 mg b.i.d., and hydrochlorothiazide, 50 to 100 mg daily, for the treatment of renovascular hypertension. Specifically monitored were the effects of therapy on blood pressure and pulse, renal function, and the renln-angiotensin-aldosterone axis. Enalapril and hydrochlorothiazide therapy produced excellent control of blood pressure with no adverse side effects. After approximately 8 weeks of therapy, renal vascular resistance was decreased and no adverse effects on glomerular filtration rate or renal blood flow were noted, except in one patient with a functional unilateral stenotic kidney. Patients receiving enalapril and hydrochlorothiazide showed stimulation of plasma renin activity and suppression of plasma angiotensin II, although the initial degree of suppression was not sustained in all patients during prolonged therapy. Although plasma aldosterone concentration was initially suppressed, the degree of suppression was not sustained. Nine patients have been followed for an additional 6 months; none have experienced further progression of renal disease, as assessed by repeated measurements of glomenilar filtration and effective renal plasma flow. These results suggest that combined enalapril and hydrochlorothiazide therapy is safe and effective in the medical management of renovascular hypertension and that blood pressure control may be achieved in the absence of sustained interruption of the renin-angiotensin-aldosterone system.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Agonists of dopamine receptors can lower blood pressure by vasodilation through action on dopamine) receptors, inhibition of sympathetic nerve activity by action on dopamine2receptors, or actions in the central nervous system. Fenoldopam, a selective dopamine1agonist, piribedil, a selective dopamine2agonist, and dipropyl dopamine1a mixed dopamine1and dopamine2agonist, were injected intravenously in pentobarbital-anesthetized, spontaneously hypertensive rats (SHR). The mechanism for the antihypertensive effect was evaluated by administration of the selective dopamine1antagonist SCH 23390 and the selective dopamine2antagonist domperidone. While SCH 23390 only antagonized the hypotensive effects of fenoldopam, domperidone abolished the fall in blood pressure produced by dipropyl dopamine and piribedil but not by fenoldopam. Increments in heart rate and plasma norepinephrine levels accompanied the hypotensive effects of fenoldopam. The increase in heart rate was abolished by a dose of SCH 23390 sufficient to completely block the hypotensive effects and was significantly attenuated by the ganglionic blocking agent hexamethonium, which suggests that the increase in heart rate was due to a baroreceptor reflex. Fenoldopam does not cross the blood-brain barrier, which suggests that its hypotensive effect was mediated by peripheral dopamine1receptors. Since domperidone does not cross the blood-brain barrier and significantly antagonized the hypotensive and bradycardic effects of dipropyl dopamine and piribedil, these effects were mediated primarily by peripheral dopamine2receptors. These results indicate that SCH 23390 and domperidone are useful agents to identify the receptor subtype mediating the action of dopamine agonists in SHR.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To test the hypothesis that the hypotensive action of urapidil is in part related to a direct action on the brain, the central (intracerebroventricular) and peripheral (intravenous) effects of urapidil were studied and compared with those obtained with clonidine and prazosin. All studies were conducted in conscious, chronically instrumented stroke-prone spontaneously hypertensive rats (SHRSP). Efferent sympathetic nervous system activity was estimated by means of a Dipolar electrode implanted on the splanchnic nerve. Only clonidine, administered intracerebroventricularly and intravenously, decreased sympathetic nerve activity. Urapidil and prazosin either did not affect sympathetic nerve activity after central administration or increased it after peripheral administration at low and high doses, respectively. Centrally administered urapidil and prazosin lowered blood pressure but also blocked the response to intravenously administered phenylephrine; this result suggests a peripheral effect. Centrally administered urapidil decreased heart rate. Urapidil given either intracerebroventricularly or into the cisterna magna had no influence on baroreceptor responses. Intravenous infusions of urapidil and prazosin in sufficient doses to lower blood pressure in spontaneously hypertensive rats by 50 mm Hg completely blocked the actions of phenylephrine. These data suggest that in conscious SHRSP urapidil lowers blood pressure through peripheral blockade of α-adrenergic receptors rather than by means of central sympathetic suppression. In this regard urapidil resembles prazosin rather than clonidine; however, the effect of urapidil on heart rate is consistent with a central mode of action.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Atrial natriuretic factor lowers blood pressure in normotensive and hypertensive animal models. The present study examined the mechanism of the blood pressure-lowering effect in 10 normotensive dogs. Four awake dogs previously instrumented with electromagnetic flow probes for measurement of cardiac output and catheters for systemic hemodynamic and cardiac dynamic measurements were studied. After a 30-minute control period, a 3 Mg/kg bolus followed by 0.3 μg/min/kg of a 24-residue synthetic atrial natriuretic factor was infused for 30 minutes, followed by a 1-hour recovery period. Mean arterial pressure fell significantly during infusion (control, 125 ± 4; infusion, 108 ± 5; recovery, 125 ± 9 mm Hg;p< 0.05) and was accompanied by a slight but significant bradycardia (control, 144 ± 7; infusion, 134 ± 5; recovery, 145 ± 7 beats/min;p< 0.05). Significant reductions in cardiac output (control, 2.66 ± 0.60; infusion, 2.18 ± 0.60; recovery, 2.74 ± 0.60 L/min;p< 0.05), stroke volume (control, 18.4 ± 3.9; infusion, 16.0 ± 4.2; recovery, 19.0 ± 3.7 ml/beat;p< 0.05), and maximum increase in rate of change of left ventricular systolic pressure (control, 2475 ± 200; infusion, 2088 ± 216; recovery, 2487 ± 243 mm Hg/sec;p< 0.05) were also observed during infusion. No significant changes in total peripheral resistance or central venous pressure were noted, although the latter tended to fall during infusion. A similar pattern was observed in six pentobarbital-anesthetized dogs, except that infusion of atrial natriuretic factor did not induce bradycardia. These data indicate that mean arterial pressure is lowered in these models by a mechanism other than reduction in total peripheral resistance, namely a reduction in cardiac output.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The hypertensogenic effect of 18-oxocortisol, an aldosterone analogue possessing both mineralocorticoid and glucocorticoid properties, was studied at the same dosage but under different experimental conditions in two experiments. Under experimental conditions conducive to the development of mineralocorticoid hypertension (i.e., rats with a single kidney on a high NaCl intake), there was an extremely rapid onset of saline polydipsia and hypertension accompanied by cardiac and renal enlargement, marked thymic involution without adrenal atrophy, cardiovascular lesions, and hypokalemia. With the exception of the thymic changes, the same changes occurred in rats given the biologically equivalent dose of deoxycorticosterone acetate. Under circumstances favoring the development of glucocorticoid hypertension (i.e., intact rats on a normal sodium intake), the same dose had only a transient blood pressure-elevating effect, attaining prehypertensive levels at most, and caused neither chronic hypertension nor hypokalemia. The biologically equivalent glucocorticoid dosage of cortisol was similarly ineffective. Under these circumstances, both steroids caused thymus involution but only 18-oxocortisol caused kidney enlargement.

ISSN:0194-911X    

出版商:OVID    

年代:1986

数据来源: OVID