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 μeq/min). After VD, volume expansion increased mean arterial and right atrial pressures similarly, but induced significantly lower (P<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 μeq/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.