Catheter-based radiorefrequency renal denervation lowers blood pressure in obese hypertensive dogs.
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.
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi; Department of Pathology, University of Mississippi Medical Center, Jackson, Mississippi;
Jeffrey R
JR
Henegar
St. Jude Medical, Irvine, California;
Yongxing
Y
Zhang
St. Jude Medical, Irvine, California;
Rita
R
De Rama
St. Jude Medical, Irvine, California;
Cary
C
Hata
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi; Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi.
Michael E
ME
Hall
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi; slucas@umc.edu.
John E
JE
Hall
D000818:Animals; D001794:Blood Pressure; D017115:Catheter Ablation / Q000379:methods*; D059305:Diet, High-Fat; D004195:Disease Models, Animal; D004285:Dogs; D005919:Glomerular Filtration Rate; D006973:Hypertension; D007668:Kidney / Q000294:innervation* / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D009765:Obesity; D013562:Sympathectomy / Q000379:methods*; D013564:Sympathetic Nervous System / Q000473:pathology*
D009638:Norepinephrine
blood pressure; glomerular filtration; hypertension; obesity; renal denervation.