The effect of the renin-angiotensin system on mucosal water and sodium transfer in everted sacs of rat jejunum.

1. Mucosal water and sodium transfer were measured in everted sacs of rat jejunum.2. Rats maintained on a high sodium diet did not show consistently reduced mucosal water transfer and aldosterone also failed to stimulate transfer unless the control untreated values were low.3. Adrenalectomy produced little reduction in mucosal water transfer and aldosterone was without effect on water transfer in sacs from adrenalectomized rats.4. Vasopressin had no effect on mucosal transfer.5. Levels of water transfer were not reduced after hypophysectomy nor did aldosterone injection increase transfer.6. Mucosal water transfer in sacs from adrenalectomized-nephrectomized rats was low and was significantly increased by aldosterone injection or by injection of crude kidney extract.7. A significant increased mucosal water and sodium transfer was observed when sacs from adrenalectomized-nephrectomized rats were incubated with angiotensin at a concentration of 10(-10)g/ml.8. It is suggested that the renin-angiotensin system may be involved in the maintenance of sodium homoeostasis by a direct action on sodium transporting mechanisms.