Variations in mucosal water and sodium transfer associated with the rat oestrous cycle

1. Mucosal water and sodium transfer were measured in everted sacs of rat jejunum.2. Mucosal water transfer was higher at pro-oestrus and oestrus than at metoestrus and dioestrus.3. Injection of 10 mug aldosterone I.P. 28 hr before the experiment produced a stimulation of mucosal water and sodium transfer in sacs prepared from rats at dioestrus but not in sacs from rats at oestrus.4. A significant increase in mucosal water and sodium transfer was observed when sacs from dioestrous rats were incubated with angiotensin at a concentration of 10(-9) g/ml. No effect was obtained in sacs from oestrous rats.5. Treatment of adrenalectomized-ovariectomized rats with oestradiol caused a stimulation of mucosal water transfer 28 hr after injection.6. It is suggested that the actions of ovarian steroids on water and electrolyte metabolism might be due to increased activity of both the adrenal cortex and the renin-angiotensin system.