Effects of prazosin on autonomic control of circulation in essential hypertension

Giuseppe Mancia, Alberto Ferrari, Luisa Gregorini, Maria Carla Ferrari, Carlo Bianchini, Laura Terzoli, Gastone Leonetti, Alberto Zanchetti

Research output: Contribution to journalArticlepeer-review

Abstract

Prazosin, an antihypertensive agent that reduces blood pressure (BP) mainly through a blockade of alpha-adrenergic receptors, may, in theory, affect sympathetic control of circulation to an extent that impairs circulatory homeostasis. This possibility was studied in subjects with essential hypertension by examining the cardiovascular effects of several stimuli that induce a powerful and diversified activation of the sympathetic noradrenergic activity (dynamic and isometric exercise, cold exposure) and of stimuli that exert a powerful inhibitory influence upon the sympathetic nervous system (carotid baroreceptor reflex). Before and after 15 days of continuous administration of prazosin (2-5 nig), 3 times a day, measurements were made of BP (intraarterial catheter), heart rate, cardiac output (tbermodilution), and peripheral resistance. Prazosin reduced mean arterial pressure (10%) and peripheral resistance (9%) at rest, and it did not affect heart rate and cardiac output. Neurally mediated changes in arterial pressure, cardiac output, and peripheral resistance during dynamic or isometric exercise and cold exposure were unaffected by the drug; also unaffected were the cardiovascular responses to increase and decrease in carotid baroreceptor activity obtained by varying carotid transmural pressure through a variable neck pressure chamber device. Thus, the hypotensive and vasodilating effect of prazosin in essential hypertension is not accompanied by an impaired response to neural excitation influences upon the cardiovascular system. Also, the inhibitory influences originating from the carotid baroreflex are unchanged. These data indicate that circulatory homeostasis is largely preserved during administration of prazosin at clinically effective doses.

Original languageEnglish
Pages (from-to)700-707
Number of pages8
JournalHypertension
Volume2
Issue number5
Publication statusPublished - 1980

Keywords

  • Alpha-adrenergic.blockade
  • Carotid baroreflex
  • Circulatory homeostasis
  • Noradrenergic activity
  • Prazosin
  • Sympathetic nervous system

ASJC Scopus subject areas

  • Internal Medicine

Fingerprint Dive into the research topics of 'Effects of prazosin on autonomic control of circulation in essential hypertension'. Together they form a unique fingerprint.

Cite this