Chemical Blockade of the Sympathetic Nervous System in Essential Hypertension

Moser, Marvin

doi:10.1001/archinte.1952.00240050022002

Cited by 13 publications

(1 citation statement)

References 26 publications

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“…Criteria for selection, baseline investigations and patient characteristics were as described previously. 1 All subjects gave written, informed consent. The study was approved by the Human Research Review Committee, University of Texas Health Science Center at Dallas.…”

Section: Methodsmentioning

confidence: 99%

Hemodynamic and neuroendocrine responses to acute and chronic alpha-adrenergic blockade with prazosin and phenoxybenzamine.

Mulvihill-Wilson¹,

Gaffney²,

Pettinger³

et al. 1983

Circulation

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SUMMARY We investigated the relevance of the selective a1-adrenergic receptor blockade produced by prazosin to its blood pressure-lowering efficacy in man. The hemodynamic and neuroendocrine responses to the acute and chronic oral administration of prazosin and phenoxybenzamine were compared in a randomized, double-blind, placebo-controlled, crossover study of 11 patients with essential hypertension. These responses were also evaluated during lower body negative pressure and dynamic bicycle exercise, which produce potent but diversified activation of the sympathetic nervous system. In the acute studies, arterial blood pressure decreased to similar levels with prazosin or phenoxybenzamine; however, hemodynamic and neuroendocrine responses differed both before and during sympathetic nervous system activation. Prazosin lowered arterial blood pressure by reducing total peripheral resistance (p < 0.05). In contrast, phenoxybenzamine produced a modest reduction in cardiac output (8%, p < 0.05) with little change in total peripheral resistance, forearm vascular resistance or forearm blood flow. Additionally, plasma norepinephrine concentration and heart rate rose to significantly higher levels with prazosin (p < 0.02) than with phenoxybenzamine, a difference that was most evident with lower body negative pressure or dynamic exercise. Baroreceptor control of arterial pressure homeostasis was preserved with both agents, except during marked degrees of cardiovascular stress. With chronic therapy, the circulatory responses adapted to the a-adrenergic antagonists, and both drugs produced similar hemodynamic and neuroendocrine profiles. The differences with acute administration may be the result of a more rapid onset of action and a more marked degree of a-adrenergic blockade with prazosin than with phenoxybenzamine therapy, rather than to any difference in their a1-and a2-adrenergic receptor blocking properties. Moreover, the findings of the present study suggest that the prejunctional a2-receptor, autoinhibitory to sympathetic neuronal norepinephrine release, is of no functional significance in patients with essential hypertension. SINCE their introduction in the 1950s,1-3 a-adrenergic antagonists have fallen into disrepute as therapeutic agents for the treatment of essential hypertension because of intolerable side effects such as tachycardia, postural hypotension and impotence and because of their weak antihypertensive effects.4 Prazosin, a recently developed a-adrenergic antagonist,5 6 is an effective antihypertensive agent that chronically produces little change in heart rate, cardiac output and renin release.7' 8 The absence of reflexogenic effects with this agent may be explained by the finding in animal studies that prazosin blocks only a,-adrenergic receptors, which mediate vasoconstriction, and not a2-adrenergic receptors, which control stimulus-induced norepinephrine release from sympathetic nerve terminals.9-" Thus, with prazosin, it has been postulated that prejunctional a2-adrenergic receptors remain functiona...

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Section: Methodsmentioning

confidence: 99%

Hemodynamic and neuroendocrine responses to acute and chronic alpha-adrenergic blockade with prazosin and phenoxybenzamine.

Mulvihill-Wilson¹,

Gaffney²,

Pettinger³

et al. 1983

Circulation

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Cardiovascular Diseases

Schaaf¹

1954

AMA Arch Intern Med

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It has been hypothesized that Helicobacter pylori (Hp) infection may contribute to reduced stature, risk of hypertension or obesity. The aim was to evaluate body indices in Hp positive and negative persons. A total of 2436 subjects (4-100 years old) were tested for Hp status by 13 C-urea breath test. Data on height and weight were collected for 84%, and blood pressure for 80% of the study subjects. The prevalence of Hp infection was 41.6%. The odds ratio for a 10-year increase in age was 1.21 (95% CI 1.17-1.25, p-value <0.001). Statistically significant negative association of Hp positivity with body height was most pronounced in the younger age groups, while a positive association of Hp positivity with body mass index was only seen in those aged 15+ years. There was a negative effect of Hp positivity on systolic and diastolic blood pressure in subjects below 25 and a relatively strong positive effect on blood pressure in subjects over 65 years. Residual confounding by social characteristics as a possible explanation for the associations of Hp positivity with height and blood pressure cannot be excluded. Unmeasured factors related to social and family environment may cause the apparent association between Hp positivity and children's growth and blood pressure.

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Use of "Dibenzyline" as a Vasodilator in Patients With Severe Digital Ischemia

Friend¹

1954

Arch Intern Med

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Chemical Blockade of the Sympathetic Nervous System in Essential Hypertension

Cited by 13 publications

References 26 publications

Hemodynamic and neuroendocrine responses to acute and chronic alpha-adrenergic blockade with prazosin and phenoxybenzamine.

Hemodynamic and neuroendocrine responses to acute and chronic alpha-adrenergic blockade with prazosin and phenoxybenzamine.

Cardiovascular Diseases

Use of "Dibenzyline" as a Vasodilator in Patients With Severe Digital Ischemia

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