Molecular Pharmacology, Vol 11, 361-368, Copyright © 1975 by the American Society for Pharmacology and Experimental Therapeutics

On the Similar Effects of Chemical Reduction and Electrical Stimulation in Walking Leg Nerve Bundles of the Spider Crab

¹ Department of Biochemistry and Pharmacology, Tufts University School of Medicine, Boston, Massachusetts 02111

Fluorescence techniques have been used to measure the binding of Mercurochrome to crustacean leg nerve bundles and reversal of binding by 2-mercaptoethanol. It was demonstrated that both parameters are increased by electrical stimulation of the nerve bundle. In this study it is shown that prior treatment of the nerve preparation with dithiothreitol or hydrazine sulfate increases the binding and the conduction-blocking activity of Mercurochrome to about the same extent as that induced by electrical stimulation. Following chemical reduction, electrical stimulation produces no further increase in binding or conduction block by the mercurial over and above the effect of reduction alone. Unlike electrical stimulation, however, reducing agents do not increase the release of bound Mercurochrome or reversal of the conduction block by 2-mercaptoethanol. The data are compatible with the possibility that electrolytic reduction of disulfides may be involved in a conformational change in membrane proteins during electrical excitation.