Role of right atrial receptors in the control of drinking in the rat.

Balloons were implanted at the junction of the superior vena cava and right atrium of the rat. Inflation of the balloon stretched the vein-atrial junction but did not cause a change in either arterial or central venous blood pressure. Inflating the balloon attenuated spontaneous night-time water intake and the drinking responses to 24 h water deprivation and subcutaneous (s.c.) isoprenaline (10 micrograms/kg body wt.). Water intake after I.P. hyperoncotic colloid (polyethylene glycol 20 M) was virtually abolished when the balloon was inflated immediately before giving access to water (4 h after injection). Inflating the balloon had no effect on drinking following I.V. hypertonic saline (5 ml 2M-NaCl/kg body wt.). These results support the hypothesis that volume receptors on the right side of the heart are involved in controlling water intake.