title: On the mechanism of the anti-hypertensive effect of Ca++-blockers.
abstract: Cardiovascular effects induced by nifedipine and verapamil were examined in normo- and hypertensive animals to investigate the role of Ca++ -antagonists in antihypertensive therapy. Intra-arterial administration of nifedipine or of verapamil to anesthetized dogs by the intracerebroventricular (icv, 1 and 10 micrograms/kg in 1 min), or intravertebral (0.1 and 1 mg/kg in 5 sec) or intra common carotid artery (0.1 and 1 mg/kg in 5 sec) produced hypotension and sinus bradycardia and slightly reduced the pressor response induced by carotid occlusion. The latter effect was also reduced when the drugs were infiltrated into the walls of carotid sinuses (0.1 ml/sinus of a 1% solution). The antihypertensive effect of nifedipine and verapamil depends on their Ca++ antagonist and vasodilator properties. However, our study suggests CNS vasomotor involvement also.
mesh_terms: D000758:Anesthesia; D000818:Animals; D000959:Antihypertensive Agents; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000188:drug therapy; D006977:Hypertension, Renal / Q000188:drug therapy; D007276:Injections, Intraventricular; D009543:Nifedipine / Q000494:pharmacology; D051381:Rats; D014628:Vagotomy; D014700:Verapamil / Q000494:pharmacology
chemical_list: D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D014700:Verapamil; D009543:Nifedipine