Inhibition by SKF 525A and quinacrine of endogenous glibenclamide-sensitive K+ channels in follicle-enclosed Xenopus oocytes.

Effects of local anesthetics-related drugs, SKF 525A (proadifen, a cytochrome P450 inhibitor) and quinacrine (a phospholipase A2 inhibitor) on glibenclamide-sensitive K+ currents were investigated using native Xenopus oocytes. SKF 525A and quinacrine suppressed cromakalim-induced/glibenclamide-sensitive K+ currents with IC50 values of 9.8 microM and 4.4 microM, respectively. Inhibitors of either cytochrome P450 or phospholipase A2, which are structurally unrelated to local anesthetics, however, did not affect the K+ currents. Similar results were obtained for Y-26763-induced/glibenclamide-sensitive K+ currents. SKF 525A and quinacrine block the glibenclamide-sensitive K+ currents by a mechanism irrelevant to the inhibition of cytochrome P450 or phospholipase A2 in oocytes.