Denervated and intact kidney responses to exercise in the dog

In conscious female dogs exercise-induced changes in the function of the innervated and denervated kidney were studied by clearance techniques. The animals were prepared for experiments by chronic unilateral renal denervation and surgical division of the urinary bladder to enable separate urine collection from each kidney. A 20-min run on a treadmill at a speed of 2.6 m/s significantly decreased urine flow, osmolar clearance, sodium excretion, as well as clearances of exogenous creatinine and p-aminohippurate in the denervated kidney only. In dogs running at 3.6 m/s renal hemodynamics decreased significantly and similarly for both kidneys, whereas the fall in renal excretion was virtually limited to the denervated kidney. As glomerular filtration rate (GFR) was falling during exercise, sodium excretion per 100 ml GFR tended to increase in the innervated kidney, in contrast to an expected slight fall on the denervated side. This indicated a defect of tubular sodium reabsorption of the innervated kidney. On the whole, the data do not support an important mediatory role of renal nerves in the mechanism of renal function changes during exercise.