Vagally mediated regulation of renal function in conscious primates

The effects of vagal denervation (VD) were examined on responses of Na+ and water excretion to acute volume expansion (18 ml/kg of 6% dextran in saline) in six conscious rhesus monkeys with chronic sinoaortic denervation (SAD). After SAD, volume expansion increased mean arterial pressure (from 95 +/- 6.6 to 119 +/- 7.5 mmHg), right atrial pressure (from 1.3 +/- 0.7 to 5.9 +/- 1.8 mmHg), urine flow (from 0.08 +/- 0.01 to 0.68 +/- 0.20 ml/min), and Na+ excretion (from 1.30 +/- 0.45 to 29.51 +/- 10.40 mueq/min). After VD, volume expansion increased mean arterial and right atrial pressures similarly, but induced significantly lower (P less than 0.05) increases in urine flow (from 0.05 +/- 0.01 to 0.19 +/- 0.03 ml/min) and Na+ excretion (from 0.87 +/- 0.27 to 11.50 +/- 6.13 mueq/min). Thus vagal mechanisms appear to play an important role in mediating excretion of Na+ and water in response to acute volume expansion in the conscious primate.