A small-conductance charybdotoxin-sensitive, apamin-resistant Ca(2+)-activated K+ channel in aortic smooth muscle cells (A7r5 line and primary culture).
A small conductance K+ channel was identified in smooth muscle cells of the rat aortic cell line A7r5 and also in rat aortic smooth muscle cells in primary culture, using conventional single-channel recording techniques. The single-channel conductance shows no rectification, either in the range -70 to +40 mV under asymmetrical conditions (9.1 pS), or in the range -100 to +50 mV in symmetrical 150 mM K+ (37 pS). Channel activity is reversibly inhibited by extracellular application of charybdotoxin, with a concentration of 8 nM producing half-maximal inhibition. It is unaffected by apamin or scyllatoxin. Channel activity depends on the presence of free Ca2+ on the cytosolic face of the membrane, with an activation zone between 0.1 and 1 microM. This small-conductance, charybdotoxin-sensitive, Ca(2+)-regulated K+ channel is activated by vasoconstrictors such as vasopressin and endothelin.
Van Renterghem
C
C
Institut de Pharmacologie Moléculaire et Cellulaire, C.N.R.S., Valbonne, France.
Lazdunski
M
M
D000818:Animals; D001011:Aorta / Q000502:physiology; D001030:Apamin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D018999:Charybdotoxin; D004553:Electric Conductivity; D009132:Muscles / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D012604:Scorpion Venoms / Q000494:pharmacology*
D015221:Potassium Channels; D012604:Scorpion Venoms; D018999:Charybdotoxin; D001030:Apamin; D002118:Calcium