Renal nerves and postprandial renal excretion in the conscious monkey

Experiments were performed in conscious macaque monkeys to determine if the renal nerves are important in mediating postprandial increases in renal fluid-electrolyte excretion in this species. Monkeys were given a high-sodium meal via a nasogastric tube. Consecutive 10-min urine samples were taken during the 30-min time of meal administration and then 180 min postprandially. The experiment was performed both before and 10-14 days after each animal underwent renal denervation. Diuresis and natriuresis occurred under both renal-innervated and -denervated conditions. However, the amounts of urine and sodium excreted were less after renal denervation. For the total 210 min of measurements obtained after the meal was started, cumulative urine output was 95.0 ± 26.4 ml and sodium excretion 7.18 ± 1.74 meq in innervated kidneys vs. 56.7 ± 7.0 ml (a 40% decrease; P < 0.005) and 4.84 ± 0.99 meq (a 33% decrease; P < 0.01) after denervation. These results demonstrate that the renal nerves are important in the nonhuman primate for eliciting the postprandial changes in urinary excretion secondary to intake of a high-sodium meal.