title: Catheter-Based Radiofrequency Renal Denervation: Location Effects on Renal Norepinephrine.
abstract: BACKGROUND
  Clinical studies indicate that blood pressure (BP)-lowering effects of radiofrequency (RF) renal denervation (RD) are sustained for up to 2 years, although a recent clinical trial failed to find a major effect compared to sham treatment. In most previous studies, the efficacy of RD has not been assessed. The current study determined whether RD in different regions of the renal artery causes different degrees of RD as assessed with renal norepinephrine (NE) levels.
  
  
  RESULTS
  Unilateral RD was performed on 14 pigs divided into 3 groups: RD near the ostium, in the main renal artery near the bifurcation, and in extrarenal branches of the renal artery. After 2 weeks post-RD, the pigs were euthanized, renal cortex tissue was collected for NE measurement, and renal arteries were prepared for histological analysis. Renal NE decreased by 12% with RD at the ostium, 45% with RD near the bifurcation in the main renal artery, and 74% when RD was performed in extrarenal artery branches. The number of renal nerves was greatest in extrarenal branches and in the main artery compared to the ostium and the average distance from the lumen was greatest for nerves at the ostium and least at the branches.
  
  
  CONCLUSIONS
  RF RD lowers renal NE more significantly when performed in branches of the renal artery closer to the kidney. Increased efficacy of RF RD in extrarenal arterial branches may be due to the greater number of nerves in close proximity to the artery lumen in the branches.
authors.affiliation: Department of Medical Pharmacology, University of Missouri, Columbia, Missouri, USA; henegarj@missouri.edu.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Henegar
authors.affiliation: Center for Innovation and Strategic Collaboration, St. Jude Medical, Inc., Irvine, California, USA;
authors.forename: Yongxing
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Center for Innovation and Strategic Collaboration, St. Jude Medical, Inc., Irvine, California, USA;
authors.forename: Cary
authors.initials: C
authors.lastname: Hata
authors.affiliation: Center for Innovation and Strategic Collaboration, St. Jude Medical, Inc., Irvine, California, USA;
authors.forename: Irvin
authors.initials: I
authors.lastname: Narciso
authors.affiliation: Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, USA; Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hall
authors.affiliation: Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, USA;
authors.forename: John E
authors.initials: JE
authors.lastname: Hall
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D015536:Down-Regulation; D007668:Kidney / Q000098:blood supply* / Q000378:metabolism*; D023421:Models, Animal; D009638:Norepinephrine / Q000378:metabolism*; D011859:Radiography; D012077:Renal Artery / Q000000981:diagnostic imaging / Q000294:innervation / Q000601:surgery*; D013552:Swine; D013562:Sympathectomy / Q000379:methods*; D013997:Time Factors
chemical_list: D009638:Norepinephrine
keywords: blood pressure; hypertension; norepinephrine; radiofrequency ablation; renal denervation; renal nerves.