Barbiturates increase the rate of voltage-dependent inactivation of the calcium current in snail neurones.
Effects of barbiturates (thiopentone, pentobarbitone, phenobarbitone and barbitone) on the calcium current (ICa) in identified Helix neurones were studied, using a conventional suction pipette technique. Barbiturates depressed the maximal peak amplitudes (MPA) of ICa in a dose-dependent manner without shifting the current-voltage relationships along the voltage axis. Barbiturates accelerated the decay phase of ICa at high concentrations (1 X 10(-4) to 3 X 10(-3) M), at which concentrations double-pulse experiments showed the increased rate of a voltage-dependent inactivation of ICa. It is concluded that the acceleration of the decay phase of ICa by barbiturates may be due to the increased rate of the voltage-dependent inactivation of ICa.
D000818:Animals; D001463:Barbiturates / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology*; D004558:Electric Stimulation; D006372:Helix, Snails; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*
D001463:Barbiturates; D007473:Ion Channels; D002118:Calcium