EFFECTS OF THE INTRACEREBROVENTRICULAR ADMINISTRATION OF KETAMINE ON CENTROGENIC ARRHYTHMIAS IN ANESTHETIZED RATS

In urethane anesthetized rats the icv (lateral cerebral ventricle) adm inistration of ketamine, at the highest utilized doses, induced bradyp nea and sinus bradycardia in spontaneously breathing rats. Moreover, i t partially antagonized the arrhythmogenic activities of sodium glutam ate and sodium aspartate, as well as desipramine and ouabain. From the se results, we conclude that ketamine had an inhibitory effect on the centrogenic arrhythmias not only acting at the level of NMDA subtype r eceptor, but also at beta(1) adrenergic central receptors. Moreover at high doses, ketamine can also induce centrogenic arrhythmias in spont aneously breathing rats.