Aortic baroreceptor deafferentation diminishes saline-induced drinking in rats

The effect of bilateral surgical deafferentation of the baroreceptors in the aortic arch and carotid sinus on experimentally induced water intake was investigated in rats. Drinking was induced by subcutaneous administration of one of the following agents: hypertonic saline, polyethylene glycol, isoproterenol and angiotensin II, or by 18 h of water deprivation. Hypertonic saline-induced drinking was significantly attenuated after bilateral denervation of either the aortic arch plus the carotid sinus or the aortic arch alone. However, this diminished response disappeared when hypertonic saline was given in subsequent tests. The initial drinking deficit following hypertonic saline was independent of the time elapsed since the animals had undergone surgery. All other thirst challenges tested resulted in water intake that was not statistically different from sham-operated control groups. It is concluded that aortic baroreceptor deafferentation initially results in a diminished drinking response following hypertonic saline, possibly due to interruption of afferent information originating in osmosensitive areas in the aortic arch. A role of arterial baroreceptors in the regulation of non-osmotically induced water intake is not supported by the present data.