Molecular and pharmacological studies of human vascular-type ATP-sensitive K+ channels regarding the channel kinetics

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Potassium channels which are inhibited by intracellular ATP (ATP_i) were first identified in ventricular myocytes, referring to as ATP-sensitive K^+ channels (i.e. K_<ATP> channels). Subsequently, K^+ channels with similar characteristics have been demonstrated in many other tissues (pancreatic β-cells, skeletal muscle, central neurones, smooth muscle). Approximately one decade ago, K_<ATP> channels were cloned and were found to be composed of at least two subunits : an inwardly-rectifying K^+ channel six family (Kir6.x) which forms the ion conducting pore and a modulatory sulphonylurea receptor (SUR) that accounts for several pharmacological properties. Various types of native K_<ATP> channels have been identified in a number of visceral and vascular smooth muscles in single-channel recordings. However, little attention has been paid to the molecular properties of the subunits in K_<ATP> channels and it is important to determine the relative expression of K_<ATP> channel components which give rise to native K_<ATP> channels in smooth muscle. The aim of this study was to investigate molecular properties of K_<ATP> channels with a main interest in the molecular basis of native K_<ATP> channels and to discuss their possible linkage with physiological functions in smooth muscle. We have prepared the original article which will be submitted to some journal soon.