Calcium antagonists and neural control of circulation in essential hypertension

Giuseppe Mancia, Gianfranco Parati, Guido Grassi, Guido Pomidossi, Cristina Giannattasio, Roberto Casadei, Antonella Groppelli, Antonio Saino, Luisa Gregorini, Rodolfo Perondi, Alberto Zanchetti

Research output: Contribution to journalArticle

Abstract

Data from animals and from man suggest that calcium antagonists interfere with aadrenergic receptors and that this mechanism may be responsible for some of the vasodilation induced by these drugs. However, a-adrenergic receptors play a primary role in baroreceptor regulation of the cardiovascular system and blood pressure homeostasis, which might therefore be adversely affected by calcium antagonist treatment. We addressed this question in 14 essential hypertensives studied before treatment, 1 h after 20 mg oral nitrendipine and 5-7 days after daily administration of 20 mg oral nitrendipine. Blood pressure was measured by an intra-arterial catheter, heart rate by an electrocardiogram, cardiac output by thermodilution and forearm blood flow by venous occlusion plethysmography. Total peripheral and forearm vascular resistances were calculated by dividing mean blood pressure by blood flow values. Plasma norepinephrine was also measured (high performance liquid chromatography) in blood taken from the right atrium. Compared with the pretreatment values, acute nitrendipine administration caused a fall in resting blood pressure, an increase in the resting heart rate and cardiac output, and a fall in resting peripheral and forearm vascular resistance. The resting hypotension and vasodilation were also evident during the prolonged nitrendipine administration, which was, however, accompanied by much less resting cardiac stimulation than that observed in the acute condition. Baroreceptor control of the heart rate (vasoactive drug method) was similar before and after acute and prolonged nitrendipine treatment. This was also the case for carotid baroreceptor control of blood pressure (neck chamber technique) and for control of forearm vascular resistance as exerted by receptors in the cardiopulmonary region (lower-body negative- pressure and passive leg-raising techniques). The increases in blood pressure, cardiac output and total peripheral resistance induced by a cold pressor test and isometric exercise were also superimposable before and after the acute and more prolonged administration of nitrendipine. Even the cardiovascular adjustments to dynamic exercise (increase in blood pressure, heart rate and cardiac output, decrease in peripheral resistance) were superimposable before and after drug administration. These observations show that reflex control of circulation and blood pressure homeostasis are not adversely affected by acute and prolonged administration of nitrendipine at doses capable of exerting an antihypertensive effect. Although this does not exclude an a-blocking action by this drug, it indicates that any such action does not interfere with sympathetic cardiovascular control.

Original languageEnglish
Pages (from-to)S49-S55
JournalJournal of Hypertension
Volume5
Publication statusPublished - 1987

Keywords

  • Baroreflexes
  • Blood pressure
  • Cardiac output
  • Cardiopulmonary reflexes
  • Exercise
  • Hypertension
  • Nitrendipine
  • Peripheral circulation

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Internal Medicine
  • Endocrinology

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  • Cite this

    Mancia, G., Parati, G., Grassi, G., Pomidossi, G., Giannattasio, C., Casadei, R., Groppelli, A., Saino, A., Gregorini, L., Perondi, R., & Zanchetti, A. (1987). Calcium antagonists and neural control of circulation in essential hypertension. Journal of Hypertension, 5, S49-S55.