Sodium and potassium metabolism in the newt ( Triturus cristatus carnifex Laur.) : VIII. Effects of injections of sodium and potassium chloride and distilled water

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Female newts ( Triturus cristatus carnifex Laur.). have been injected with distilled water, or solutions of sodium chloride and potassium chloride. Sham-injection (skin puncture) was also performed. The results were as follows: (1) The treatments did not produce any effect on the water content of muscles (except in the skin-punctured newts); (2) injections of distilled water and sodium chloride increased the sodium content of muscles; (3) the sham-injections produced a decrease in muscle sodium content; (4) the sham-injections and loading with distilled water increased muscle potassium; (5) potassium chloride injections caused a decrease in muscle potassium content; (6) all the treatments (particularly sodium loading) increased sodium excretion into the surrounding water; and (7) potassium excretion increased in water- and potassium-loaded newts. The results obtained were analyzed by means of the discriminant analysis on the basis of five variables: muscle water content; muscle sodium content and potassium content, both in reference to wet weight; sodium loss; and potassium loss into the surrounding water. There was good discrimination between: normal newts and sham-injected ones; intact newts and water-, sodium-, and potassium-loaded animals; sham-injected newts and animals loaded with either distilled water or sodium or potassium chloride; and water-loaded newts and sodium- or potassium-loaded animals. The discriminant analysis made it possible to distinguish between effects due to stress from skin puncture and effects produced by the vehicle or effects produced by the salts injected, and to arrive at the following conclusions: (a) in Triturus cristatus carnifex Laur. skin puncture inhibits interrenal function; (b) administration of distilled water causes sodium retention by muscle, probably due to increased release of hormone(s) with effects similar to those of aldosterone; (c) sodium loading enhanced sodium excretion; (d) potassium loading caused potassium loss from muscles by an unknown mechanism.