Use-dependent effects of 4-aminopyridine on transient outward current in dog ventricular muscle.
The use-dependent features of 4-aminopyridine-induced block of the transient outward current were investigated under voltage clamp conditions in dog ventricular myocardial bundles. The block depended strongly on the pattern of voltage clamp pulses. Its level (settled in rested membranes) became deeper at early time during depolarization. In contrast, prolonged depolarization (above 50 to 100 ms) produced relief of block. Our results suggest that the block strongly depends on the state of the channel gating system.
Simurda
J
J
Department of Biophysics, Research Institute of Medical Engineering, Brno-Bohunice, Czechoslovakia.
Simurdová
M
M
Christé
G
G
D015761:4-Aminopyridine / Q000494:pharmacology*; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D003035:Cobalt / Q000494:pharmacology; D004285:Dogs; D004553:Electric Conductivity; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006352:Heart Ventricles / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D016276:Ventricular Function
D015220:Calcium Channels; D007473:Ion Channels; D015221:Potassium Channels; D003035:Cobalt; D015761:4-Aminopyridine