title: Blood pressure and heart rate response to apomorphine in urethane anesthetized rats.
abstract: The mechanisms involved in the hypotensive effect of apomorphine were studied in urethane anesthetized rats. The intravenous injection of apomorphine (0.01-0.75 mg/kg) produced a dose dependent fall in mean blood pressure. At the higher doses used (0.5-0.75 mg/kg) a marked bradycardia accompanied the hypotensive effect. These cardiovascular effects were prevented by pretreating the animals with pimozide (0.01-0.1 mg/kg). Low doses of haloperidol (0.03-0.3 mg/kg) did not antagonize the hypotensive action of apomorphine. Higher doses of haloperidol (1-3 mg/kg) reduced markedly the mean blood pressure. Atropine (1 mg/kg) partially antagonized the decrease in mean blood pressure induced by apomorphine and prevented completely the bradycardia. Hexamethonium (10 mg/kg) reduced the mean blood pressure and when apomorphine was administered, a residual hypotensive effect and no bradycardia was observed. It is concluded that the cardiovascular actions of apomorphine are central in origin and mainly due to the stimulation of a dopamine receptor. A probable peripheral effect could not be discarded.
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006220:Haloperidol / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects*; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D010868:Pimozide / Q000494:pharmacology; D051381:Rats
chemical_list: D006584:Hexamethonium Compounds; D010868:Pimozide; D001285:Atropine; D006220:Haloperidol; D001058:Apomorphine