ACTION OF VERATRINE AND MEMBRANE STABILIZERS ON NERVES

¹ Ayerst, McKenna and Harrison Ltd., Montreal, Canada
² Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois

The interaction of veratrine and membrane stabilizers on nerve conduction was investigated on A fibers of intact and desheathed sciatic nerves of frogs and on A and C fibers of isolated tail nerve of rats, by measuring the threshold voltage of stimulation and the frequency at which the nerves could conduct.

A synergism between the blocking action of veratrine and membrane stabilizers on desheathed frog nerves occurred, provided membrane stabilizers were applied in a concentration which blocked nerve conduction within 20 to 30 minutes.

Low concentrations of membrane stabilizers (which by themselves did not block the conduction in 20 to 30 minutes) delayed the onset of veratrine block on desheathed frog nerves.

Low concentrations of membrane stabilizers (including Ca⁺⁺, Mg⁺⁺ and dibucaine) temporarily restored the conduction of the desheathed nerves blocked by veratrine (0.01 to 0.0001%). However, the threshold of excitation was higher and the frequency at which nerves could conduct was much lower than that of the normal nerves.

The quaternary benzyl derivatives of dibucaine and cocaine did not differ in their effects on desheathed nerves from dibucaine and cocaine.

No qualitative difference between nerves of frogs and nerves of mammals was found with respect to the interaction of veratrine and membrane stabilizers.