Renal denervation and sodium balance in young spontaneously hypertensive rats

In 7-week-old male, spontaneously hypertensive rats (SHR) and matched normotensive control rats, Wistar Kyoto Rats (WKY), a bilateral renal denervation was performed. In two additional groups of rats a sham denervation was done (SHRS, WKYS). The animals were then kept in metabolic cages during a 10-day period during which sodium intake, urine volume, urinary sodium excretion, fecal sodium excretion, urinary aldosterone excretion and plasma renin activity were determined. Fractional urinary excretion of sodium was higher in the denervated SHR (p less than 0.1) and WKY (p less than 0.05) during the first 3 days after denervation, but during the following 3-day periods no difference between denervated and sham-operated groups was noted. The difference in fractional urinary excretion of sodium initially was due to a diminished urinary sodium excretion in the sham-operated groups since both SHRS and WKYS exhibited a significant increase between the first and the last 3-day period. Urine volume increased significantly in both SHR and WKY after denervation. Urinary aldosterone excretion on the 7th day after denervation was significantly lower in SHR compared to WKY, but there was no significant difference between the denervated and sham-operated groups. PRA was also significantly lower in SHR but no significant decrease was seen after denervation.