Recovery of ADH activity in the urine of goats under normal and stimulated conditions

Abstract

The hydrated goat was used for bioassays of antidiuretic hormone (ADH) activity recovered by resin column separation from the urine of other animals of the same species. A methodological innovation in the separation procedure was ethanol purification of the column before elution. In this manner substances which sometimes obscured the bioassays were eliminated without loss of ADH activity. With the bioassay method employed, it was possible to determine to the nearest 0.5 of a mU the ADH activity of unknown samples, provided they contained between 0-5 mU of ADH. When arginine vasopressin was infused intravenously into hydrated animals, slightly more than 10% of its antidiuretic activity was recovered in the urine. In the water replete goat the ADH activity found in the urine was of the order of 1 mU per hr urine secretion, indicating a neurohypophyseal ADH release of approximately 5 muU/kg min. After 48 h of dehydration in an environmental temperature of 20 degrees C the renal ADH excretion increased to about 8 mU/h, suggesting an 8-fold increase of ADH secretion over basic, water replete secretion of ADH. ADH secretion of the same high order was induced in hydrated animals by the infusion of angiotensin II together with hypertonic NaCl into the lateral cerebral ventricle.