NOREPINEPHRINE EFFLUX EVOKED BY POTASSIUM-CHLORIDE IN CAT SYMPATHETIC-NERVES - DUAL MECHANISM OF ACTION

Using a dialysis technique, prominent efflux of norepinephrine (NE) fr om cardiac sympathetic nerve endings was observed under local administ ration of potassium chloride (KCl, 100 mM). KCl induced NE efflux was suppressed by omega-conotoxin GVIA or desipramine but residual efflux of NE was still detectable. In the presence of omega-conotoxin GVIA, K Cl induced efflux of NE was augmented by pretreatment with reserpine, indicating that this efflux of NE was derived from axoplasma with neur otransporter. These data suggest that a KCl induced brisk increase in dialysate NE levels might occur as a consequence of exocytotic NE rele ase and carrier mediated outward NE transport from nerve endings. (C) 1998 Elsevier Science B.V. All rights reserved.