title: Epinephrine activates outward rectifying K channel in Madin-Darby canine kidney cells.
abstract: Patch-clamp recordings were used to study the epinephrine dependent activation of ion channels in the cell membrane of cultured subconfluent renal epithelial (MDCK) cells. The patch-current was dominated by two populations of K channels. The spontaneously active population of K channels shows an inward rectifying behavior. Addition of epinephrine to the cell exterior, after the patch-pipette had been sealed to the cell membrane, increased the open probability of the inward rectifying K channel and shifted the membrane potential in the hyperpolarizing direction. The epinephrine induced hyperpolarization occurs in the range of seconds and is caused by activation of outward-rectifying K channels. The outward-rectifying K channel could not be observed under control conditions. Epinephrine activated channels always appeared in clusters of four to nine channels. Both populations of K channels are modulated in their open probability by cytoplasmic free calcium and voltage.
mesh_terms: D000818:Animals; D002460:Cell Line; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology*; D007473:Ion Channels / Q000187:drug effects*; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D011188:Potassium; D004837:Epinephrine