A calcium-activated potassium channel in growth plate chondrocytes: regulation by protein kinase A.
Single channel K+ currents were recorded from inside-out patches of membrane obtained from cultured chicken growth plate chondrocytes. With a symmetrical 140 mM concentration of K+ across the cell membrane, a large conductance (211 pS), outward-rectifying, K+ channel was identified. Opening of this channel was dependent on the presence of internal Ca2+ with half maximal activation of the channel occurring with 3 microM Ca2+. The channel was blocked by internal application of tetraethylammonium (IC50 = 45 mM) and 1 mM Ba2+. Application of the catalytic subunit of protein kinase A to the cytosolic membrane resulted in over a three-fold increase in the open probability for the channel. Thus, growth plate chondrocytes contain a large-conductance, Ca(2+)-activated K+ channel which can be up-regulated during stimulation of protein kinase A.
Long
K J
KJ
Department of Pharmacology, University of South Carolina, School of Medicine, Columbia 29208.
Walsh
K B
KB
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D002645:Chickens; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D008564:Membrane Potentials; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011336:Probability; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D001464:Barium; D019789:Tetraethylammonium; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium; D004229:Dithiothreitol