title: Activation of calcium-sensitive potassium channels in L6 skeletal myocytes by arginine vasopressin requires extracellular calcium.
abstract: The effects of extracellular application of arginine vasopressin (AVP) upon membrane currents in L6 skeletal myocytes was investigated using the whole-cell configuration of the patch-clamp technique. At 0 mV AVP produced large amplitude, transient outward currents that reversed when the clamping potential was changed to -100 mV (negative to EK). The effects of alterations in the extracellular K+ concentration upon the current reversal potential suggested that the current elicited by AVP was carried mainly by K+ ions. Intracellular dialysis with 10 microM inositol 1,4,5-trisphosphate (InsP3) elicited similar currents but only in 6/14 cells. Inclusion of 5 mg ml-1 heparin in the intracellular solutions was ineffective at inhibiting the current responses to AVP. The AVP-induced current was totally abolished when the intracellular EGTA concentration was increased from 0.05 mM to 10 mM or Ca2+ was removed from the extracellular perfusing solution. These results suggest that AVP produces activation of a Ca(2+)-sensitive K+ conductance in L6 skeletal myocytes by a process dependent upon extracellular Ca2+ and not intracellular Ca2+ release.
authors.affiliation: Pharmaceutical Sciences Institute, Aston University, Aston Triangle, Birmingham, UK.
authors.forename: M
authors.initials: M
authors.lastname: Gosling
authors.forename: J W
authors.initials: JW
authors.lastname: Smith
authors.forename: D R
authors.initials: DR
authors.lastname: Poyner
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D005110:Extracellular Space / Q000502:physiology; D008564:Membrane Potentials; D009132:Muscles / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats
chemical_list: D002614:Chelating Agents; D015221:Potassium Channels; D001127:Arginine Vasopressin; D004533:Egtazic Acid; D002118:Calcium