Abstract
BACKGROUND: Obesity-induced hypertension appears to be due, in part, to increased renal sympathetic activity. Catheter-based renal denervation (RD) has been reported to lower arterial blood pressure (BP) in humans with resistant hypertension, many of whom are obese. This study was performed to assess the impact of radiofrequency-induced RD on renal function, BP, renal norepinephrine (NE), and histology of nerves along the renal artery in obese, hypertensive dogs, an experimental model that closely mimics cardiorenal and metabolic changes in obese hypertensive humans. METHODS: After control measurements of cardiovascular and renal function were obtained in obese dogs fed a high-fat diet, bilateral RD was performed using the St. Jude Medical EnligHTN RD system. After RD, BP was measured continuously for 8 weeks, and glomerular filtration rate (GFR) was measured biweekly for 6 weeks. At the end of the study, renal arteries were collected for histological analysis, and kidneys were obtained for NE measurement. RESULTS: Eight weeks after RD, systolic BP fell from 157 ± 5 mm Hg pre-RD to 133 ± 3 mm Hg (P < 0.01), and mean arterial pressure decreased by 9 mm Hg compared with pre-RD (P < 0.01). There were no significant changes in GFR. Renal nerve injury was most prevalent 0.28-3.5mm from the renal artery lumen. RD caused injury in 46% of the renal nerves observed and reduced renal tissue NE by 42% (P < 0.01). CONCLUSIONS: Catheter-based RD with the St. Jude Medical EnligHTN system lowers BP in obese dogs without significantly compromising renal function.