Neural control of renal excretory function during behavioral stress in conscious dogs

The renal and neural mechanisms underlying the excretory response to behavioral stress (aversive conditioning) were examined in 30 conscious dogs. Twenty-one dogs decreased urine flow more than 20% during stress, whereas 9 dogs showed less than a 10% decrease. In 11 of the 21 renal-reactive dogs, decreases in urine flow (42%) and sodium excretion (45%) were associated with unchanged glomerular filtration (-1.5%; GFR; inulin clearance) and effective renal blood flow (-4%; RBF; p-aminohippurate clearance). In the other 10 renal-reactive dogs, similar declines in urine flow (54%) and sodium excretion (52%) occurred with decreases in GFR (24%) and RBF (27%). Among all 30 dogs, greater increases in cardiovascular activity during stress were associated with greater decreases in renal excretion. Surgical renal denervation abolished the excretory response to stress in 4 of 5 dogs. These findings suggest that excretory responses in most dogs are mediated 1) primarily via increased tubular reabsorption rather than decreased GFR, 2) via central integration with cardiovascular responses, and 3) via the renal nerves.