Effects of the nitric oxide synthase inhibitor N omega nitro-L-arginine methyl ester on electrical activity and ion channels of mouse pancreatic B cells.

The effects of the nitric oxide (NO) synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) were studied on electrical activity, K+ATP currents and voltage-dependent K+ and Ca2+ channel currents in mouse pancreatic B cells. In the presence of 15 mM glucose, L-NAME (> 5 mM) depolarized the B cell membrane and electrical activity became continuous. The depolarization caused by L-NAME was not reversed by the addition of a membrane permeant cyclic GMP analogue. L-NAME inhibited the whole-cell K+ATP current reversibly by reducing the single channel current conductance and open probability. The results are consistent with the assumption that L-NAME depolarizes the B cell membrane by a direct action on the K+ATP channel. L-NAME also influenced the whole-cell current through voltage-dependent K+ and Ca2+ channels.