Cardiovascular afferent signals and drinking in response to hypotension indogs

Arterial hypotension stimulates increases in plasma arginine vasopressin (A VP), plasma renin activity (PRA), and water intake in conscious dogs. We ha ve previously reported that increasing left atrial but not right atrial pre ssure completely blocks the increase in plasma AVP and PRA induced by hypot ension. The goal of the present study was to examine the effect of increasi ng right or left atrial pressure on water intake induced by arterial hypote nsion. Dogs were prepared with occluding cuffs on the thoracic inferior ven a cava, the pulmonary artery, and the ascending aorta. We reduced mean arte rial pressure (MAP) 25% below control by either inferior vena cava constric tion (IVCC), pulmonary artery constriction (PAC), or ascending aorta constr iction (AAC) and measured water intake over a 2-h period. Cumulative water intake during IVCC (n = 6) and PAC (n = 6) was 7.8 +/- 2.0 and 6.7 +/- 2.6 ml/kg, respectively. There was no difference between either the latency or the volume consumed between the two treatments. In contrast, none of the do gs drank during hypotension induced by AAC (n = 5). Because the degree of a rterial baroreceptor unloading was the same in each treatment by design, we conclude that stimulation of left atrial receptors inhibits drinking in re sponse to arterial hypotension but that stimulation of right atrial recepto rs has no effect on the response in dogs.