Denervated and intact kidney responses to saline load in awake and anesthetized dogs

The function of the innervated and denervated kidney was examined in clearance studies with unilaterally renal-denervated conscious and anesthetized dogs before and after saline loading. Barbiturate anesthesia distinctly depressed hemodynamics and excretory function of both kidneys and increased the difference between the denervated and innervated organ. In conscious moderately hydrated dogs the denervated kidney excreted slightly more sodium and water, while after saline loading higher excretion was observed on the innervated side. The denervated-to-innervated kidney ratios for UNaV, UNaV/100 ml GFR, and urine flow fell significantly from mean control values of 1.27, 1.27, and 1.20, respectively, to 0.80, 0.87, and 0.77 after extracellular volume expansion. Similar alterations of the ratios were observed in anesthetized dogs, but higher excretion of the denervated kidney persisted after saline loading. It is concluded that the greater natriuretic response of the intact kidney to saline infusion was due to inhibition of sodium-retaining action of renal efferent nerve activity by acute extracellular volume expansion.