Role of renal nerves in compensatory adaptation to chronic reductions in sodium intake.

The aim of this study was to investigate the importance of the renal nerves in adaptation to chronic reductions in sodium intake. Conscious dogs with unilateral (n = 7) or bilateral (n = 4) renal denervation were studied. In dogs studied before and after bilateral denervation, there were no differences in urine volume (UO), Na excretion (UNaV), or fractional reabsorption of Li (FR Li, an index of proximal tubular Na reabsorption) between innervated and denervated kidneys on either normal (80 meq/day) or low Na intake (5 meq/day, 15 days). Plasma renin activity (PRA) was attenuated following denervation on both normal (0.39 +/- 0.06 vs. 0.18 +/- 0.01 ng angiotensin I X ml-1 X h-1) and low Na intake (1.00 +/- 0.06 vs. 0.59 +/- 0.01). In unilaterally denervated dogs the left kidney was denervated and the bladder was split, allowing continuous urine collection from separate innervated and denervated kidneys in the same dog. There was no difference in UO between innervated and denervated kidneys on normal (80 meq/day) or low (7 meq/day, 9 days) Na intake. UNaV averaged 33.6 +/- 1.3 and 37.6 +/- 2.1 meq/day in innervated and denervated kidneys, respectively, on normal Na intake and 3.5 +/- 0.5 and 4.0 +/- 0.4 meq/day in innervated and denervated kidneys on low Na intake. FR Li was not different in denervated compared with innervated kidneys during normal or low sodium intake. Norepinephrine content was reduced by 99 +/- 1% in denervated kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)