CHANNEL ACTIVATORS REGULATE ATP-SENSITIVE POTASSIUM CHANNEL (KIR6.1) EXPRESSION IN CHICK CARDIOMYOCYTES

ATP-sensitive potassium channels (K-ATP) are widely expressed and yet little is known about the mechanisms regulating their expression. Here we report that expression of chick heart Kir6.1 is regulated by chann el activators. Activation of K-ATP with either ATP depletion or pinaci dil, up-regulated Kir6.1 mRNA 1.8- to 2.4-fold in cultured ventricular myocytes as measured by competitive PCR. Pinacidil treatment also inc reased Kir6.1 protein as detected using an antibody to Kir6.1. Glibenc lamide, a K-ATP inhibitor, completely blocked the pinacidil-induced in crease in Kir6.1 levels. It appears that Kir6.1 is up-regulated by an unknown signal transduction pathway initiated by K-ATP opening. (C) 19 97 Federation of European Biochemical Societies.