The Effect of Vasopressin and Aldosterone on the Distribution of Water, Sodium, and Potassium and on Work Performance in Old Rats

Abstract

The inability of old rats to perform work effectively is associated with a distortion in the transcellular distribution of sodium, potassium, and water in skeletal muscle. Basically, this is characterized by a marked gain in total sodium, a corresponding loss of potassium and a shift of water from cells to environment, all combining to reduce the transmembrane concentration gradients of both major cations. The administration of a modest amount of pitressin tannate in oil to old male rats during a four week period, especially when accompanied by a trace of aldosterone, improved work performance significantly. This improvement was associated with a partial reversal of the distorted pattern of ionic distribution in the old animals.