Nebennieren undrenale Oxytocin-Wirkungen bei der Ratte

Summary

No significant improvement in water diuresis was obtained by the s. c. injection of 500–1000 mU/kg of a synthetic oxytocin preparation (Syntocinon) in adrenalectomized, salt-maintained rats given 18 ml of water per rat by stomach tube. In these animals oxytocin had, on the other hand, a strong natriuretic and chloruretic effect.

In intact rats the diuretic activity of oxytocin was more pronounced in thirsty than in hydrated animals. The diuretic, natriuretic, chloruretic and kaliuretic potency of oxytocin in thirsty rats was enhanced by a 3 day course of Cortisone (25 mg/kg · day s. c.). In Cortisone-treated, as opposed to untreated intact rats, oxytocin also increased the renal excretion of endogenous creatinine.

Adrenalectomy (with subsequent administration of 0.9 per cent NaCl solution as drinking fluid) suppressed the diuretic and natriuretic activity of oxytocin in thirsty rats. In adrenalectomized non-hydrated rats treated with Cortisone, oxytocin slightly increased the renal excretion of endogenous creatinine, but did neither enhance diuresis nor renal ecxretions of sodium, potassium or chloride.

The following conclusions are discussed: 1. The impairment of water diuresis in adrenalectomized rats does dot seem to be related to an increase in endogenous vasopressin activity, since it cannot be counteracted by oxytocin. 2. The diuretic activity of oxytocin may be in some way related to a stimulation of adrenocortical secretion of Cortisone-like corticosteroids.