Role of renal nerves in onset and maintenance of spontaneous hypertension

Renal denervation has been reported to delay development of hypertension in Okamoto spontaneously hypertensive rats (SHR) but to have no effect on the final hypertensive state. However, functional reinnervation begins to occur about 1 mo after renal denervation. The arterial pressure of SHR undergoing repeated bilateral renal denervations at the age of 4, 7, 10, 13, and 16 wk was compared with that in sham-operated SHR. In addition, the effect of successive renal denervations at 4, 7, and 10 wk of age in Wistar-Kyoto (WKY) control rats was determined. Both indirect measurement of pressure by the tail-cuff technique and mean arterial pressure (MAP) measurement indicated that renal denervation prevents full expression of hypertension in SHR. MAP in 19-wk-old renal-denervation SHR averaged 159 +/- 5.1 mmHg (SE) vs. 178 +/-0 4.2 mmHg in sham-operated SHR. Renal denervation had no effect on arterial pressure of WKY rats. Renal norepinephrine content in the renal-denervated WKY rats and SHR was less than 20% of that in the sham-operated groups. Successive bilateral renal denervations every 3 wk blocks 30-40% of the expected progressive elevation of arterial pressure in aging SHR.