Radiofrequency renal nerve denervation decreases blood pressure, sympathetic activity and renal norepinephrine content in spontaneously hypertensive rats (875.16)

Abstract

Radiofrequency renal denervation (RF‐RDN) decreases blood pressure (BP) in patients with drug‐resistant hypertension. This study investigated the effects of RF‐RDN on sympathetic activity and BP (Systolic, SBP; Diastolic, DBP) in SHR. Methods Nineteen‐week old male SHR were instrumented with telemetry probes for chronic measurement of BP and BP variability (BPV). After 1‐week, control BP was measured in rats for 3 days. The next day SHR (n=6/group) were anesthetized and randomly received either bilateral Sham‐RDN or RF‐RDN of the renal arteries (Biosense Webster Stockert 70 generator and RF‐probe). BP was then measured in SHR for 8 weeks. Results Following RF‐RDN, SBP/DBP was significantly decreased the day after (153±8/102±4 mmHg) and throughout the post‐RDN study (4‐week SBP/DBP, 173±7/120±5; 8‐weeks, 171±6/116±4 mmHg) compared to pre‐RDN control levels (SBP/DBP, 187±9/130±5 mmHg). RF‐RDN significantly decreased the low frequency component of BPV in SHR with the peak attenuation observed at 8 weeks (LF/HF 2.2±0.2 vs 0.9±0.2); this correlated with a blunting of the hypotensive response to i.p. chlorisondamine in RF‐RDN rats. Finally, at the end of week 8, kidney norepinephrine (NE) levels in RF‐RDN rats (left, 10±10; right, 0.0±0.0 ng/g kidney) were dramatically decreased compared with levels from sham SHR (left, 130±10; right, 110±10 ng/g kidney). Conclusions These data demonstrate that in hypertensive SHR, bilateral RF‐RDN of the renal arteries decreases BP in part by chronic inhibition of sympathetic neural pathways and a decrease in renal tissue NE levels.Grant Funding Source: Biosense Webster grant IIS‐175 to DRK and FS; NIH NIGMS P20 GM103514 to DK