Calcium channels in planar lipid bilayers: insights into mechanisms of ion permeation and gating.
Electrophysiological recordings were used to analyze single calcium channels in planar lipid bilayers after membranes from bovine cardiac sarcolemmal vesicles had been incorporated into the bilayer. In these cell-free conditions, channels in the bilayer showed unitary barium or calcium conductances, gating kinetics, and pharmacological responses that were similar to dihydropyridine-sensitive calcium channels in intact cells. The open channel current varied in a nonlinear manner with voltage under asymmetric (that is, physiological) ionic conditions. However, with identical solutions on both sides of the bilayer, the current-voltage relation was linear. In matched experiments, calcium channels from skeletal muscle T-tubules differed significantly from cardiac calcium channels in their conductance properties and gating kinetics.
Rosenberg
R L
RL
Hess
P
P
Reeves
J P
JP
Smilowitz
H
H
Tsien
R W
RW
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002417:Cattle; D004553:Electric Conductivity; D006321:Heart / Q000502:physiology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D008051:Lipid Bilayers; D009539:Nicotinic Acids / Q000494:pharmacology; D009543:Nifedipine / Q000031:analogs & derivatives / Q000494:pharmacology; D009553:Nimodipine; D011188:Potassium / Q000502:physiology; D012508:Sarcolemma; D012964:Sodium / Q000502:physiology
D007473:Ion Channels; D008051:Lipid Bilayers; D009539:Nicotinic Acids; D009553:Nimodipine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D012964:Sodium; D009543:Nifedipine; D011188:Potassium; D002118:Calcium