Mammoto T, Kamibayashi T, Hayashi Y, Takada K, Yamatodani A, Yoshiya I
Department of Anesthesiology, Osaka University, Faculty of Medicine, Osaka, Japan.
J Cardiovasc Pharmacol. 1995;26 Suppl 2:S40-3.
Stimulation of central alpha 2-adrenoceptors has been known to prevent epinephrine-induced arrhythmias in halothane-anesthetized dogs. Because recent studies suggested that several physiological processes that were traditionally attributed to activation of alpha 2-adrenoceptors, such as hypotensive action, are mediated through imidazoline receptors (IRs), it may be likely that IRs are involved in the antiarrhythmic action. We investigated the hypotensive effect of rilmenidine, a selective IR agonist (1, 3, and 10 micrograms/kg i.v.), and the antiarrhythmic effects of the drug on epinephrine-induced arrhythmias during halothane anesthesia in dogs. Although the hypotensive effect of rilmenidine was not remarkable in the dose range we tested, rilmenidine increased the arrhythmogenic threshold for epinephrine in a dose-dependent manner during halothane anesthesia, achieving statistical significance at 10 micrograms/kg, the highest dose we examined. These results suggest that rilmenidine prevents epinephrine-induced arrhythmias during halothane anesthesia and that this effect is more potent than its hypotensive action.
