MODULATION OF ATP-SENSITIVE K-MUSCLE FIBERS( CHANNEL BY INSULIN IN RAT SKELETAL)

In the present study we evaluated the modulation of the sarcolemmal AT P sensitive K+ channel by insulin. The ''in vivo'' administration of i nsulin to the rats led to an hyperpolarization of the skeletal muscle fibers, This effect is antagonized by ''in vitro'' incubation of the m uscle with glybenclamide, an ATP sensitive K+ channel blocker. Patch c lamp experiments revealed that insulin enhanced the mean current of th e ATP sensitive K+ channel by a factor of 1.4. This effect is mediated by an increase of the channel open probability, while no change occur red in the single channel conductance nor in the channel density. In t he treated rats, the sensitivity of the channel to ATP and glybenclami de is abnormally reduced. Our results are consistent with an activatio n of the ATP sensitive K+ channel by insulin. This contributes to the hyperpolarization of the skeletal muscle fibers. (C) 1997 Academic Pre ss.