[Kidney renin-angiotensin system and water intake]

The authors make a review and critical evaluation of the accumulated experimental material for clarifying the question: whether drinking is physiological process due to exogenously administered angiotensin II (A-II) or to endogenous stimulation of the rena renin-angiotensin system (RAS). There is a parallel between water intake and plasma renin activity (PRA) in states like hypovolemia, hemorrhagia, hypotension, sodium loss, etc. They find sensitivity of some cerebral structures without blood-brain barrier to physiological concentations of A-II. Water intake is increased after venous administration of angiotensin-II within physiological concentrations. It is shown at the same time that central blockade of A-II does not inhibit drinking after water abstention. The authors discover that some effects, leading to an increased water intake, are not due to RAS. Nephrectomy does not alter circadian thythm of drinking of water. They discuss contradiction in experimental data and make an inference that renal RAS could not be considered as a single and sufficient factor for regulation of water intake.