BIOPHYSICAL AND PHARMACOLOGICAL PROPERTIES OF LARGE-CONDUCTANCE CA2-ACTIVATED K+ CHANNELS IN N1E-115 CELLS()

The large conductance Ca2+-activated K+ channels in differentiated mou se neuroblastoma N1E-115 cells have been studied using patch-clamp sin gle-channel current recording in excised membrane patches. These chann els displayed a unitary conductance of 200 pS under symmetrical K+ con centrations. Effects of blockade by TEA(+), Cs+ and Ba2+ were differen t and argued for distinct action mechanisms. The open probability of t hese channels increased with increasing internal calcium and membrane potential. Maximum sensitivity of these channels ranged over physiolog ical variations of internal calcium at membrane potentials close to ze ro, suggesting a physiological role for these channels in regulating t he membrane potential and Ca2+ influx through voltage-dependent Ca2+ c hannels. (C) 1994 Academic Press, Inc.