Hg2+ increases the open probability of carbachol-activated Cl- channels in Aplysia neurons.
Carbachol and acetylcholine (ACh)-activated whole-cell chloride currents were recorded in identified neurons of Aplysia californica. Application of 0.1-10 microM HgCl2 potentiated the chloride response and reduced the rate of desensitization. To investigate the underlying mechanism we recorded single chloride channels in a cell-attached patch configuration. Recordings were performed successively on the same neuron with 1 microM carbachol and with 1 microM carbachol + 1 microM HgCl2, respectively. The slope conductance did not change significantly, but there was a manyfold increase in the open probability, Po. This may underlie the Hg(2+)-induced enhancement of carbachol- and ACh-evoked chloride currents in Aplysia neurons and may serve as a model for the neurotoxic effect of Hg2+ on the mammalian ACh receptor.
Fejtl
M
M
Wadsworth Center for Laboratories and Research, New York State Dept. of Health, Albany 12201-0509.
Györi
J
J
Carpenter
D O
DO
D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology*; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects* / Q000502:physiology; D004594:Electrophysiology; D008628:Mercury / Q000494:pharmacology*; D009474:Neurons / Q000378:metabolism*; D011336:Probability
D018118:Chloride Channels; D002217:Carbachol; D008628:Mercury