Influence of oxytocin and vasopressin on sodium-retaining activity of aldosterone in the rat

¹ Laboratorio de Fisiologia, Universidad Catolica de Chile, Santiago, Chile

Changes in water, sodium and potassium excretion were studied after injection of oxytocin, vasopressin and aldosterone. Normally hydrated and overloaded rats were used. Oxytocin, 2.5, 5.0 and 10.0 mu increased sodium and potassium output. The sodium retaining activity of 0.5 and 1.0 µg of aldosterone was abolished when used in combination with 2.5 and 5.0 mu oxytocin. The antidiuretic effect of 0.5–5.0 mu vasopressin was accompanied by an increase in sodium excretion; change in potassium excretion occurred only in the 2nd hour after the injection. Suitable doses of vasopressin were also able to counteract the effect of aldosterone on sodium retention.