AJP - Cell Physiology, Vol 265, Issue 3 C674-C679, Copyright © 1993 by American Physiological Society
Ca-dependent action of cocaine on K current in freshly dissociated dorsal root ganglia from rats
J. Grossie
Department of Physiology, Ohio State University College of Medicine, Columbus 43210-1218.
The actions of cocaine on K currents were analyzed in enzymatically
dissociated neurons from adult rat dorsal root ganglia. The whole cell
voltage clamp configuration was used to determine that in the presence of
Ca cocaine inhibited a K conductance that was activated from a holding
potential of -55 mV. The cocaine concentration that decreased K currents
half-maximally was 18 microM. At a concentration of 40 microM, cocaine had
no significant effect on K current remaining in the absence of external Ca,
whereas at 80 microM a significant 17% depression of this current was
observed. Large transient K currents occurring with depolarizations from
-90 mV were also resistant to 40 microM cocaine, suggesting that cocaine
specifically inhibits a Ca-dependent K current. Ca currents elicited from a
holding potential of -55 mV were largely unaltered by 40 microM cocaine.
The data suggest that cocaine may be a useful tool for experimental
blockage of Ca-dependent K currents and also provide additional insight
into the overall actions and toxicity of the drug.
