Induction of two K+ currents by complement component C5a in mouse macrophages

Abstract

Puff application of complement component C5a (5 · 10-8 M) onto peritoneal macrophages from thioglycollate-stimulated mice induced two kinds of outward current at a holding potential of -68 mV, a slowly-rising sustained outward current and a spike-like transient outward current. Quinidine (2 · 10-4 M) and tetraethylammonium (10-2 M) partially suppressed both types of outward current. Charybdotoxin (2 · 10-6 M) markedly suppresed the spike-like outward current. Reversal potentials in bath solutions of different external K+ concentrations were dependent only on K+ concentrations. The transient current was not suppressed in Ca2+-free EGTA-containing solution, but was completely abolished in BAPTA-containing solution. One kind of single channel responding to C5a, which has a single-channel conductance of 29 pS, was recorded from cell-attached patches. These results suggest that C5a activates a Ca2+-dependent and another type of K+ current. © 1992.