A Calcium-Activated Potassium Channel in Growth Plate Chondrocytes: Regulation by Protein Kinase A

• Published in: Biochemical and biophysical research communications Vol. 201; no. 2; pp. 776 - 781
• Main Authors: Long, K.J., Walsh, K.B.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.1994
• Subjects: Adenosine Triphosphate - pharmacology; Animals; Barium - pharmacology; Calcium - physiology; Cells, Cultured; Chickens; Cyclic AMP-Dependent Protein Kinases - metabolism; Dithiothreitol - pharmacology; Ion Channel Gating - drug effects; Ion Channel Gating - physiology; Kinetics; Membrane Potentials; Potassium Channel Blockers; Potassium Channels - drug effects; Potassium Channels - physiology; Probability; Tetraethylammonium; Tetraethylammonium Compounds - pharmacology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1994.1768

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 Ca 2+ with half maximal activation of the channel occurring with 3 μM Ca 2+. The channel was blocked by internal application of tetraethylammonium (IC 50 = 45 mM) and 1 mM Ba 2+. 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.