EFFECT OF PROLACTIN AND ACTH ON SERUM AND URINE SODIUM LEVELS OF FUNDULUS KANSAE

A single injection of 20 mU of ovine prolactin into hypophysectomized Fundulus kansae increased urine flow but did not affect renal loss of sodium. Prolactin injected into intact killifish did not affect urine flow, but did reduce renal sodium loss slightly. ACTH, under the condition used, did not affect either urine flow or renal sodium loss. It did cause an elevation of serum sodium levels of control, but not hypophysectomized aniamls held in fresh water. Prolactin, but not ACTH, caused a marked elevation of the serum sodium levels of both hypophysectomized and intact killifish held in 0.4 [image]_ saline. It is concluded that the primary action of prolactin, at least in the case of F. kansae is on water metabolism.