Clonidine and carotid baroreflex in essential hypertension

Giuseppe Mancia, Alberto Ferrari, Luisa Gregorini, Alberto Zanchetti

Research output: Contribution to journalArticlepeer-review

Abstract

Clonidine is believed to reduce blood pressure by a neural action and animal experiments suggest that this consists in potentiation of baroreflexes. In 16 patients with essential hypertension we studied the effects of alterations in carotid sinus baroreceptor activity (neck chamber technique) on arterial blood pressure (catheter measurements) and heart rate, before and after Intravenous administration of 150 μg and 300 μg of clonidine. The magnitude of the reflex responses was assessed by the slope of the linear regressions relating applied increase and decrease in tissue pressure at the carotid sinus (and therefore applied decrease and increase in carotid sinus transmural pressure) and resulting changes in mean arterial pressure and R-R interval. Clonidine caused a marked reduction in mean arterial pressure (-26 ± 3 mm Hg) and a slight but significant reduction in heart rate (- 5 ± 1 b/rain). There was no evidence for a potentiation of the baroreceptor influence on blood pressure, although a slight potentiation of the baroreceptor influence on heart rate was observed in few instances. We conclude that in man clonidine can exert a pronounced hypotensive effect without potentiating baroreceptor influence on blood pressure. Therefore this mechanism does not play a prominent role in the clinical antihypertensive action of the drug.

Original languageEnglish
Pages (from-to)362-370
Number of pages9
JournalHypertension
Volume1
Issue number4
Publication statusPublished - 1979

Keywords

  • Antihypertensive drug
  • Arterial baroreflexes
  • Blood pressure
  • Carotid baroreceptors
  • Clonidine
  • Cold pressure test
  • Essential hypertension
  • Isometric exercise
  • Sympathetic activity

ASJC Scopus subject areas

  • Internal Medicine

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