Investigating the role of angiotensin II in thirst: interactions between arterial pressure and the control of drinking.

Several lines of evidence suggest that angiotensin II plays a physiological role in the control of thirst. Establishing that, however, has been surprisingly difficult, given our current knowledge about the renin-angiotensin systems in the circulation and the brain and the variety of techniques available to measure and manipulate them. A major problem is that stimulating or blocking the renin-angiotensin system affects several physiological variables simultaneously. Since several of these variables also influence the controls of water intake directly or indirectly, the interpretation of the effect on drinking becomes more difficult. To illustrate the problem and recent developments, this paper describes some of the interactions between the effects of angiotensin II on arterial pressure and thirst, and it shows how they have contributed to the controversy over the physiological role of the peptide.