Heart Rate Acceleration by Imipramine and by Noradrenaline after Imipramine; its Blockade by Dichloroisoproterenol (DCI)

Abstract

The actions of DCI (3-5 mg/kg i.v.) on the cardioacceler-ation produced by noradrenaline (1 mcg/kg i.v.) after imipramine (3 mg/kg i.v.) and on tachycardia produced by imipramine, were studied in 10 anesthetized, vagotomized dogs. The influence of imipramine on the isoproterenol tachycardia was also investigated. Confirming previous work, the tachycardia of noradrenaline is significantly increased (P< 0.001), although no significant changes (P>.05) were observed on the cardioacceleration produced by isoproterenol 1 [image]g/kg i.v. after imipramine. Heart rate acceleration provoked by both catecholamines is blocked or prevented by DCI. Imipramine sensibilizes the adrenergic cardioreceptors to adrenaline. DCI blocks and prevents cardioacceleration due to imipramine. Therefore it is concluded that tachycardia produced by imipramine could be of adrenergic nature.