[Studies of the induction of diuresis increase and water intoxication induced diuresis inhibition by oxytocin and vasopressin in lactating cattle].

Intravenous injection of 20 International Units (IU) of oxytocin in the form of synthetic oxytocin or neurohypophyseal extract preparations to dehydrated cows that had already undergone twelve hours of water withdrawal did not produce antidiuresis but rather rise of diuresis accompanied by saluretic effects. Increase in diuresis occurred also in hyperhydrated cows, following water application, provided that oxytocin or vasopressin preparations had caused antidiuresis and saluresis and, consequently, changed urine composition to osmotic pressures beyond the limit values between 650 and 750 mosmol/kg. Rehydration of cow may be associated with retardation of diuresis by four hours or more. If oxytocin or vasopressin are given in the phase of such rehydration, the period between water application and the onset of water diuresis may be defined as "blocked water diuresis". Continuous infusion of 0.34 or 0.8 IU of oxytocin per minute up to 3.5 hours did not cause water intoxication in hyperhydrated cows, though blood plasma values for osmotic pressure had dropped to 244 mosmol/kg, while Na+ concentration had gone down to 116 mmol/l.