THE EFFECT OF ADRENOCORTICAL STEROIDS ON THE TISSUE ELECTROLYTE COMPOSITION OF THE FRESH-WATER RAINBOW TROUT (SALMO GAIRDNERI)

Abstract

SUMMARY: The effects were studied of cortisol, corticosterone and aldosterone on the concentrations of sodium and potassium in muscle and blood plasma and on water content of muscle in the fresh-water rainbow trout (Salmo gairdneri). These steroids appeared to cause a loss in plasma sodium throughout the 96 hr. experimental period. An initial rise in muscle sodium was observed during the first 24 hr. after commencement of the treatments. The subsequent decline in muscle sodium was interrupted by a transient rise followed by a continuing decline. The effect of these hormones on the potassium concentrations in plasma was variable, although there was a significant rise in the potassium concentration in muscle during the period of decline in sodium concentration. The significance of these results in relation to the possible enhanced adrenocortical activity of the trout during adaptation to a marine environment is discussed.