ELECTROCHEMICAL DETECTION OF K-EVOKED QUANTAL SECRETORY EVENTS FROM ISOLATED RAT TYPE-I CAROTID-BODY CELLS()

Using amperometric techniques, electrochemical events associated with vesicular transmitter release were recorded from isolated rat type I c arotid body cells when exposed to a solution containing 50 mM K+. Even ts were enhanced in amplitude by preloading cells with the catecholami ne precursor, L-beta-3,4-dihydroxyphenylalanine (L-DOPA). K+-evoked se cretion was abolished by the non-selective Ca2+ channel blocker Cd2+ ( 100 mu M) and markedly reduced by the L-type Ca2+ channel blocker nife dipine (5 mu M). Our results indicate that secretion from isolated rat type I cells can be monitored electrochemically and we demonstrate a major role for L-type Ca2+ channels in mediating K+-evoked secretion.