Evidence for a role of inhibition of sympathetic neurotransmission in the cardiovascular effects of intravenously administered verapamil.
The effects of intravenous administration of verapamil, nifedipine and diltiazem on sympathetic stimulation-induced increase in heart rate (HR) and blood pressure (BP) have been investigated in chloralose-anaesthetized and artificially-ventilated cats. Verapamil (300 micrograms kg(-1) i.v.) produced a significant inhibition of sympathetically-induced tachycardia and pressor responses. The same dose of verapamil did not significantly alter adrenaline (2 micrograms kg(-1) i.v.) induced increase in HR and BP. In contrast, neither the sympathetically-induced nor the adrenaline-induced pressor and tachycardiac responses were significantly affected by nifedipine or diltiazem. These results demonstrate that peripherally administered verapamil but not nifedipine and diltiazem can inhibit cardiovascular sympathetic neurotransmission and this can possibly contribute to its effects on HR and BP.
Gurtu
S
S
Department of Pharmacology, King George's Medical College, Lucknow, India.
Mukerjee
D
D
Shukla
S
S
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002415:Cats; D004110:Diltiazem / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006321:Heart / Q000187:drug effects / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects; D007275:Injections, Intravenous; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*; D013610:Tachycardia / Q000139:chemically induced*; D014700:Verapamil / Q000494:pharmacology*
D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine; D004837:Epinephrine