Studies on Bradycardiac Effect of Methoxamine in Rabbits

Chung, Sung Su; Ha, In Ho

Abstract

The bradycardiac and presor to intravenous and intraventricular methoxamine were examined in urethane-anesthetized rabbits 1) Intravenous methoxamine produced bradycardiac pressor responses. Atropine (2 mg/kg, i,v.) weakened but not abloished the bradycardiac effect. 2) The bradycardiac effect elicited by intravenous methoxamine was not affected by int-ravenous prazosin, rehimbiine, guanethidine and propranolol, butt was attenuated by intra venous chlorisondamine reserpine. 3) The pressor effect elioited by intravenous methoxamine was weakened by prazosin, but was scarcely affected, rather potentiated, by intraTenous yohimblne, guanethidine, chlorisondamine, propranolol and resperpine. 4) Intraventricular methoxamine produced pressor and bradycardiac responses. 5) The bradycardiac effect elicited by intraventricular methoxamine was net affected by intravenous atropine, prasosin and yohimbine. This was attenuated by intravenous guane- thidine, chlorisondamine, propranolol and reserpine, and by intraventricular atropine prazosin and propranolol, respectively. 6) The pressor effect elicited by intraventricular methoxamine was attenuated by intra- ventricular and intravenous prazosin. This was not affected by intravenous atropine, gua-nethidine, chlorisondamine, propranolol, reserpine and yohimbine, and by intraventricular atropine, prasosin and Propranolol, respectivelr. 7) From these results it was inferred that bradycardiac effect elicited by methoxamine was not an action through the mediation of aleph 1-adrenoceptors but was a result from non-specific actions on some brain receptors.

Studies on Bradycardiac Effect of Methoxamine in Rabbits

Abstract

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