Radiofrequency renal nerve ablation decreases blood pressure in SHR accompanied by increased urinary sodium excretion (857.4)

Abstract

We have shown that radiofrequency catheter ablation of the renal arteries (RF‐RDN) decreases blood pressure (BP) in spontaneously hypertensive rats (SHR). Here, we studied the effects of RF‐RDN on changes in water and sodium excretion and urinary angiotensinogen levels in SHR with established hypertension. Methods Nineteen‐week old male SHR were instrumented with telemetry probes for measurement of BP. After 1‐week, control BP was measured. The next day SHR randomly received either bilateral Sham‐RDN (n=5) or RF‐RDN (n=6) of the renal arteries (Biosense Webster Stockert 70 generator and RF‐probe). BP (Systolic, SBP; Diastolic, DBP) was then measured for 2 weeks. Rats were then placed in metabolic cages for collection of urine and measurement of 24‐hr water and sodium balance. Results BP was significantly decreased in RF‐RDN SHR (2 weeks; ΔSBP, ‐12±5; ΔDBP, ‐9±4 mmHg) as compared to sham SHR (2 weeks; ΔSBP, ‐2±2; ΔDBP, 2±2 mmHg). RF‐RDN SHR increased urinary sodium excretion (RF‐RDN, 0.33±0.02; Sham, 0.25±0.03 mEq/day) and food intake (RF‐RDN 21±1; Sham 17±1 g/day). However, there were no significant differences between groups in 24‐hr daily water (RF‐RDN, 21±1; Sham, 19±2 ml) or sodium balance (RF‐RDN, 0.59±0.04; Sham, 0.48±0.06 mEq), or urinary angiotensinogen, protein and creatinine excretion rates. At the end of week 2, kidney norepinephrine levels in RF‐RDN rats (left, 0±0; right, 10±10 ng/g kidney) were markedly 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 produces an increase in urinary sodium excretion, which may potentially contribute to the concurrent decrease in BP.Grant Funding Source: Biosense Webster IIS‐175 to DRK & FS; P30 GM103337 to LGN; P20 GM103514 to DRK