Modulatory effects of ketamine on catecholamine efflux from in vivo cardiac sympathetic nerve endings in cats

With the use of the microdialysis technique, we examined the modulatory effect of ketamine on catecholamine efflux from in vivo cardiac sympathetic nerve endings. A dialysis probe was implanted in the left ventricular myocardium, and dialysate norepinephrine (NE) levels in anesthetized cats were measured with liquid chromatogram-electrical detection. A 60-min occlusion of the left anterior descending coronary artery caused increases in dialysate NE levels. Through the dialysis probe, locally applied ketamine (10 mM) augmented the dialysate NE responses to coronary occlusion in the presence and absence of desipramine (membrane NE transport blocker). Thus, the ketamine-induced NE increment is not mediated through the neuronal NE transporter. The sympathomimetic action of ketamine may augment the NE efflux evoked by myocardial ischemia. (C) 2002 Published by Elsevier Science Ireland Ltd.