MUTUAL EFFECT OF ELECTROGENIC IONOPHORES VALINOMYCIN AND CLCCP MAY RESULT IN A NONELECTROGENIC K+ H+ EXCHANGE ON BILAYER-LIPID MEMBRANES/

The method of pH shift measuring by means of pH microelectrode was app lied for measurements of hydrogen ion fluxes across a planar bilayer l ipid membrane (BLM) in the presence of potassium ion ionophore valinom ycin and protonophore carbonylcyanide m-chlorophenylhydrazone (CCCP) u nder conditions of voltage clamp. It was shown that at a clamped BLM v oltage, CCCP-induced H+ flux increased significantly after addition of valinomycin and depended on the potassium ion concentration. The volt age dependence of the flux was determined in the range of +/-150 mV un der the conditions of both symmetrical KCl and KCl gradient. Surprisin gly, at the clamped zero voltage on BLM, a significant hydrogen ion fl ux was observed in the presence of KCl gradient and both valinomycin a nd CCCP. This was interpreted as an induction of nonelectrogenic K+/H exchange in the presence of valinomycin and CCCP presumably through t he formation of electrically neutral complexes of these two ionophores and K+ (H+) ions: valinomycin-K+-CCCP- and possibly valinomycin-CCCP- -H+.