The Responses of Melanophores in Isolated Fish Scales

Abstract

Spaeth has shown that such preparations will respond to electrolytes as follows dispersion of pigment in Na, conc. in K. The persistence of the effect depends upon the anion, the order being C1-, Br-, NO3-, SCN- and Cl, Cl being the least toxic. The order of toxicity of cations was as follows: Na, Li, Cs and NIL, Rb. and K, Na being the least toxic. Adrenalin produces marked conc. of the pigment. Spaeth and Barbour have shown this to be reversed by previous treatment with ergot. Recent studies have shown that the response to some drugs and salts is dependent upon the integrity of the nerve endings. After complete degeneration of all nervous elements in the ''Tautog scale adrenalin still produces conc. but the alkaloids of ergot no longer reverse the response. Similarly KC1 which formerly produced conc. no longer does so in denervated scales. Atropine also prevents the conc. of melanophore pigment in the presence of KCl. These results seem to indicate that adrenalin produces conc. by acting directly upon the cell, that the reversal of the adrenalin effect by ergotoxine, however, depends upon the integrity of some receptive mechanism in the cell, that the KCl produced conc. by acting upon some point peripheral to the action of adrenalin, presumably at the nerve terminal. The Tautog melanophore disperses its pigment markedly on a sudden increase in light intensity. This is a transitory response and is followed by slow concentration. Ultra-violet radiation, as Spaeth showed, causes the opposite response, namely conc. The pulsations of isolated melanophores arc-described.