Zn2+ blocks the voltage activated calcium current of Aplysia neurons.
We have investigated the effect of Zn2+ on voltage-activated calcium currents of Aplysia neurons, using conventional two-electrode voltage-clamp techniques. The peak of these currents was reversibly reduced by Zn2+ (50% reduction at 3.75 mM; total block at 20 mM), while the current-voltage relation and the activation and inactivation curves were shifted to depolarized voltages. The effects of Zn2+ were concentration-dependent. The Hill coefficient was 1.62. The high concentrations required, the shift of the current-voltage relation and the effects on activation and inactivation are best explained by a charge-screening effect combined with a specific binding site for Zn2+ near the entrance of the channel.
Büsselberg
D
D
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany 12209-0509.
Evans
M L
ML
Rahmann
H
H
Carpenter
D O
DO
D000818:Animals; D001048:Aplysia; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002712:Chlorides / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015032:Zinc / Q000494:pharmacology*; D017967:Zinc Compounds
D015220:Calcium Channels; D002712:Chlorides; D017967:Zinc Compounds; C016837:zinc chloride; D015032:Zinc