ω-conotoxin GVIA, the N-type calcium channel inhibitor, is sympatholytic but not vagolytic: Consequences for hemodynamics and autonomic reflexes in conscious rabbits

Abstract

We investigated the effects of the N-type calcium channel blocking agent, ω-conotoxin GVIA, on the resting hemodynamics and on some autonomic reflexes in the conscious rabbit. ω-Conotoxin 3 and 10 μg/kg i.v. reduced mean arterial blood pressure by 16 ± 2 and 25 ± 3 mm Hg, respectively, over 30 min accompanied by a tachycardia. Renal vascular conductance (Doppler flow-meter) increased by 27.6 ± 3.7 and 38.6 ± 10.3% at 30 min after ω-conotoxin 3 and 10 μg/kg, respectively. Vasodilatation was also observed but to a lesser extent in the hindquarter and mesenteric vascular beds. The baroreceptor-heart rate reflex was evoked by a drug method (bolus injection of sodium nitroprusside and phenylephri..