Expression of ATP-sensitive Potassium Channel and Sulfonylurea Receptor in Neonate and Adult Rat Tissues

Expression of ATP-sensitive Potassium Channel and Sulfonylurea Receptor in Neonate and Adult Rat Tissues

<P> The ATP-sensitive potassium (K<SUB>ATP</SUB>) channel is a member of inward rectifier potassium channel (Kir) that is inhibited by intracellular ATP and functions in close relation to sulfonylurea receptors (SUR). Although the molecular mechanism and physiological function of K<SUB>ATP</SUB> channels are well understood, the expression pattern during development or treatment with the channel modulators such as glybenclamide is little known. In this work, we determined mRNA levels of a K<SUB>ATP</SUB> channel (Kir6.2) and a sulfonylurea receptor (SUR2) in rat tissues by RNase protection assay. Levels of Kir6.2 and SUR2 mRNA in the rat brain and skeletal muscle were higher in adult (90∼120 days) than in neonate (2∼8 days), whereas those in the heart were not much different between neonate (2∼8 days) and adult (90∼120 days). In addition, none of K<SUB>ATP</SUB> channel modulators (opener, pinacidil and nicorandil; blocker, glybenclamide) affected the Kir6.2 mRNA levels in the heart, brain and skeletal muscle. The results indicate that the expression of Kir and SUR genes can vary age-dependently, but the expression of Kir is not dependent on the long-term treatment of channel modulators. The effect of the channel modulators on mRNA level of SUR is remained to be studied further.