Suppression by calmodulin of glutamate-induced potassium current in identified snail neurons

Using the voltage-clamp technique combined with pressure injection, we examined the inhibitory action of glutamate (Glu) in identified snail neurons. Calimidazolium and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), calmodulin inhibitors, enhanced a slow outward current (Glu) current induced by Glu in a dose-dependent manner. This Glu current was suppressed by intracellular injection of calmodulin. However, no significant change in the Glu current was observed when either CaCl2 or EGTA was intracellularly applied. These results suggest a novel calmodulin-mediated process, through which Glu induces an outward current.