EFFECTS OF LOCAL-ANESTHETICS AND RELATED DRUGS ON ENDOGENOUS GLIBENCLAMIDE-SENSITIVE K-OOCYTES( CHANNELS IN XENOPUS)

Effects of local anesthetics and structurally related drugs on the gli benclamide-sensitive K+ currents evoked by Y-26763 (a K+ channel opene r) were investigated in native Xenopus oocytes. The K+ current induced by Y-26763 (100 muM) was reversibly suppressed by all six local anest hetics tested in a concentration-dependent manner with the rank order of potencies (IC50 in muM): bupivacaine (67) > dibucaine (136) > tetra caine (845) > lidocaine (1710) = mepivacaine (1945) > procaine (3112). (+)-Propranolol and mexiletine also suppressed Y-26763-induced K+ cur rents with IC50 values of 115 muM and 789 muM, respectively. These res ults suggest that a suppressive action on glibenclamide-sensitive K+ c hannels is the common property of local anesthetics.