The Action of Ephedrine on Melanophores.

Abstract

Nadler 1 found that in the squid, Loligo pealii, ephedrine injected subcutaneously, produced a local blanching which was considered as due to an inhibition of the smooth muscle of the chromatophore system and a generalized reddish coloration ascribed to a stimulation of the central nervous system. These experiments have been repeated on several other kinds of fish, namely Cyprinus rubrofuscus, Mylopharyngodon aethiops, Cyprinus abbreviatus and Ophiocephalus argus and they all responded by a generalized paleness. Examination of the scales showed that all the melanophores were contracted. One fish remained in such state for 36 hours. It appears therefore that, in the fresh water fish studied, ephedrine does not exert a double action, or both the peripheral and the central actions bring about a similar change, namely contraction of the black pigment cells. Experiments with adrenalin appear to substantiate the latter view, since this drug caused only a local blanching and no generalized paleness of the scales.

The generalized contraction of the melanophores caused by ephedrine has been found to be true also in the frog, Rana nigromaculata. Injection into the dorsal lymph sac of 20 mg. per kilo caused the skin of the frog to remain pale for 6 hours.

Other observations on small, salt water fish, Trigentiger bifasciatus and Microcanthus serrus, with a few drops of ephedrine solution added to the surrounding sea water showed in a minute or even less a generalized blanching and the melanophores began to contract. The contraction gradually became more marked and in 15 to 20 minutes most of the black pigment cells contracted to their minimal sizes. This contraction of the melanophores usually lasted from one half hour to 2 hours, after the fish had been transferred to ordinary sea water, depending upon the time of the previous immersion in the ephedrine-sea water.