SINGLE-CHANNEL ACTIVITY-INDUCED IN MITOPLASTS BY ALKALINE PH

Exposure of patch-clamped mitoplasts to alkaline pH induces a reversib le conductance increase (Antonenko, Yu. N., Kinnally, K.W. and Tedesch i, H. (1991) J. Membr. Biol. 124, 151-158) which is due to an increase in open probability of a channel activity of 15 pS and larger transit ions. The present study defines in more detail some of the characteris tics of the channel activity involved in this conductance increase. Th e results suggest the presence of two channels one slightly cation-sel ective of approx. 15 pS (referred to here as alkaline-induced cation-s elective activity, ACA) and another slightly anion selective of approx . 45 pS (referred to as alkaline-induced anion-selective activity, AAA ). The possible implication of these results in relation to other chan nels and the permeability transitions reported by others using mitocho ndrial suspensions is discussed.