The occurrence of stable subconductance levels in Na(+)-activated K+ channels in excised membrane patches from guinea-pig ventricular myocytes.
Twelve short-lived subconductance levels have been recognized in potassium channels activated by intracellular Na+ (KNa channels) in membrane patches excised from guinea-pig ventricular myocytes. When stable recording was achieved over a prolonged period (> 30 min), sojourns of opening to one of two stable subconductance levels (approximately 30 and 70% of the main-state level) occurred spontaneously. These periods of activity showed similar kinetics (open and closed time distributions) to those of openings to the main-state conductance. Opening to transient sublevels was still detected during openings of the channel to the stable sublevels. These results suggest that the KNa channel has a complex oligomeric structure, in which twelve separate pores would seem to be functionally organized into either three or four domains that show a high degree of co-operativity in their gating.
Mistry
D K
DK
British Heart Foundation Research Group, Department of Physiology, School of Veterinary Science, Bristol, UK.
Tripathi
O
O
Chapman
R A
RA
D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D004553:Electric Conductivity; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology; D015640:Ion Channel Gating; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*; D012964:Sodium / Q000502:physiology*; D016276:Ventricular Function
D015221:Potassium Channels; D012964:Sodium