EFFECT OF HYPOPHYSECTOMY ON THE FUNCTION OF THE KIDNEY OF THE EURYHALINE TELEOST, FUNDULUS KANSAE

Abstract

The effect of hypo-physectomy of F. kansae (Cyprinodontidae) was studied in fresh water and following transfer to sea water. Urine flow, glomerular filtration rate, urine and serum osmotic pressure, Na and K concentration and percent water were measured. Hypophysectomy resulted in reduced urine flow, elevated urinary electrolytes and osmotic pressure, and a drop in serum electrolytes and osmotic pressure in fresh water. Hypophysectomized fish were slower in shutting-off urine flow following transfer to sea water and did not produce blood-hypertonic urine. Pre-adaptation to saline increased the ability of hypophysectomized animals to respond to an osmotic challenge, but they did not respond as well as their controls.