DOUBLE-GATING MECHANISM AND DIVERSITY OF AN ADENOSINE-TRIPHOSPHATE (ATP)-SENSITIVE K+ CHANNEL IN NEURONS ACUTELY DISSOCIATED FROM RAT NEOCORTEX

Classically, ion channels are classified into 2 groups: chemical-sensi tive (ligand-gated) and voltage-sensitive channels. Single ATP-sensiti ve K+(K-ATP) channel currents were recorded in acutely dissociated rat neocortical neurons using patch clamp technique. A type of K-ATP chan nel has been found to be gated not only by intracellular ATP, but also by membrane potential ( V-m), and proved to be a novel mechanism unde rlying the gating of ion channels, namely bi-gating mechanism. The res ults also show that the K-ATP channels possess heterogeneity and diver sity. These types of K-ATP channels have been identified in 40.12% of all patches, which are different in activation-threshold and voltage-s ensitivity. The present experiment studied the type-3 K-ATP channel wi th a unitary conductance of about 80 pS in detail ( n = 15). Taking ac count of all the available data, a variety of K-ATP channels are sugge sted to exist in body, and one type of them is bi-gated by both chemic al substances and membrane potentials. This property oi the K-ATP chan nels may be related to their pathophysiological function.