Electrochemical detection of K+-evoked quantal secretory events from isolated rat type I carotid body cells

Abstract

Using amperometric techniques, electrochemical events associated with vesicular transmitter release were recorded from isolated rat type I carotid body cells when exposed to a solution containing 50 mM K+. Events were enhanced in amplitude by preloading cells with the catecholamine precursor, L-β-3,4-dihydroxyphenylalanine (L-DOPA). K+-evoked secretion was abolished by the non-selective Ca2+ channel blocker Cd2+ (100 μM) and markedly reduced by the L-type Ca2+ channel blocker nifedipine (5 μM). 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.