Direct effects of diltiazem, nifedipine and verapamil on peripheral sympathetic nerve function, cardiac impulse conduction and cardiovascular function in anesthetized dogs subjected to ganglionic blockade

European Journal of Pharmacology
J L Bergey, D R Much

Abstract

The Ca2+ entry blockers diltiazem, nifedipine and verapamil produced dose-dependent increases in atrioventricular conduction time (A-H interval), while decreasing heart rate and mean arterial pressure in anesthetized dogs previously subjected to ganglionic blockade to prevent hypotension-induced reflex changes in sympathetic tone. Nifedipine and verapamil, but not diltiazem, also reduced (P less than 0.05) the tachycardia produced by electrical stimulation of the cardioaccelerator nerve at doses which did not alter the heart rate response to direct beta-adrenoceptor stimulation by isoproterenol (0.1 microgram/kg i.v.). The lowest doses of nifedipine (0.03 mg/kg) and verapamil (0.3 mg/kg) that produced decreases in mean arterial blood pressure were the same as or greater than those which selectivity reduced the tachycardiac effects of low frequency (1 Hz, 25-35 V, 5 ms), but not high frequency (10 Hz, 25-35 V, 5 ms) cardiac nerve stimulation. These data suggest that threshold vasodilator doses of some Ca2+ blockers may selectively reduce low level (or basal) sympathetic neurotransmission and this additional pharmacologic action may contribute to the antihypertensive mechanism. The failure to inhibit the high frequency nerve resp...Continue Reading

References

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Citations

May 1, 1987·Clinical and Experimental Pharmacology & Physiology·J Staszewska-Woolley
May 1, 1988·Cardiovascular Drugs and Therapy·P R Lichtlen
May 10, 2003·American Journal of Physiology. Heart and Circulatory Physiology·J K Choate, R Feldman

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