Sodium and potassium metabolism in the newt ( Triturus cristatus carnifex Laur.) : VI. Effects of cortisol, and cortisol and aldosterone injected simultaneously

Abstract

Female newts ( Triturus cristatus carnifex Laur.) have been injected with aldosterone, cortisol, and cortisol + aldosterone. Sham-treatment consisting of injections of distilled water was also performed. Sodium retention by, and potassium loss from the muscles were consistently observed after treatment with the hormones, confirming previous findings with aldosterone. Similar, though weaker effects, as with aldosterone, were also obtained with cortisol. When aldosterone and cortisol were simultaneously administered the effects were slightly enhanced. Under the experimental conditions used there seemed to be no antagonism between mineralo- and glucocorticoids with regard to the effect on muscle sodium and potassium content in Triturus. The results obtained were analyzed by means of discriminant analysis on the basis of three variables: (a) muscle water content; (b) muscle sodium, and (c) muscle potassium content, in reference to wet weight. The analysis demonstrated good discrimination between: (a) normal newts and newts injected with either aldosterone or cortisol, or with cortisol + aldosterone; (b) newts treated with these hormones and controls (i.e., newts injected with distilled water); (c) newts treated with the two hormones simultaneously and newts injected with either aldosterone or cortisol. Discriminant analysis of the results showed not only that sodium and potassium metabolism were affected by the hormones, but also that the variation in muscle sodium content was almost invariably the most discriminative parameter.