ISSN:
1432-1041
Keywords:
nifedipine
;
prazosin
;
hypertension
;
alpha1-adrenergic blockade
;
calcium antagonism
;
vasodilatation
;
plasma noradrenaline
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
Summary The hypotensive effect of vasodilator monotherapy in hypertension is attenuated by a baroreceptor-mediated increase in the sympathetic release of noradrenaline. Nifedipine induces a rise in noradrenaline release, but it is not known to affect noradrenaline-induced vascular contraction of smooth muscle to a clinically significant degree. The haemodynamic and hormonal effects of a single sublingual dose of nifedipine 20 mg in 8 moderately hypertensive patients have been studied before and during postsynaptic alpha1-blockade with prazosin. The antihypertensive effect of nifedipine was significantly increased by prazosin pretreatment (fall in mean arterial pressure 60 min after nifedipine: −16.7% with and −8.5% without prazosin), despite similar increases in plasma noradrenaline. Prazosin alone caused no change in supine blood pressure for 2 h after an oral dose of 2 mg. The findings are in keeping with the hypothesis that prazosin blocks a compensatory reaction to vasodilatation caused by nifedipine.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00544078
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