Abstract
It remains unclear whether renal sympathetic nerve activity (RSNA) influences chronic regulation of renal sodium excretion. The present study was designed to examine the contribution of RSNA to long-term regulation of renal sodium excretion and sodium balance during changes in low, normal, and high sodium intake. Male Wistar rats were subjected either renal denervation (RD; n=9) or Sham surgery (n=17) and instrumented chronically with bipolar stainless steel electrodes for measurements of RSNA, electrocardiogram and electromyogram. The rats consumed very low-sodium pellet diet throughout and drank 4 different NaCl drinking solutions: 0 (low sodium), 50 (normal sodium), 154 (high sodium), and 308 (high sodium) mEq/L NaCl drinking solution. The experiment consisted of a 3 day control period (normal sodium), 3 days sodium unloading (low sodium)/loading (high sodium), and 3 days recovery period (normal sodium). During low sodium intake, cumulative sodium balance progressively decreased in both Sham and RS rats while the magnitude of decrease in the cumulative sodium balance in RD rats was greater than that in Sham rats. During high sodium intake, the magnitude of increase in the cumulative sodium balance in Sham rats was greater than that in RD rats. These data suggest that RSNA play a significant role in retaining sodium within the body during low sodium intake and also even during high sodium intake in rats. [J Physiol Sci. 2008;58 Suppl:S115]
