Effects of renal sympathetic nerve radiofrequency ablation on norepinephrine spillover rate and sympathetic nerve activity in dogs with hypertension

Objective 　To evaluate the validity and explore the mechanism of renal sympathetic denervation (RSD) in the treatment of dogs with hypertension reproduced by constriction of abdominal aorta. Methods 　The hypertension model was reproduced by constriction of abdominal aorta in 20 adult healthy dogs. These dogs were then randomly divided into the treatment group and control group (10 each). Renal sympathetic nerve radiofrequency ablation was done in treatment group 1 month after modeling. The foreleg blood pressure, sympathetic activity and norepinephrine overflow rate of dogs in two groups were detected before modeling, and 1, 2 and 3 months after modeling, and the trend of the change was also observed. Results 　One month after modeling, the systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP) were elevated significantly in control group (146.7±21.0, 89.0±12.7 and 108.3±14.9mmHg) compared with those before modeling (119.5±13.2, 76.5±7.8 and 90.9±8mmHg, P < 0.05). The renal sympathetic activity impulse and norepinephrine spillover rate were also enhanced significantly (P < 0.05). The renal sympathetic nerve activity obviously decreased in the treatment group after the operation, and then increased 2 months after the ablation. The norepinephrine spillover rate in treatment group increased significantly 1 month after modeling (P < 0.05), and decreased after ablation, and it lasted to the end of the experiment (P < 0.05). One and two months after ablation, the norepinephrine spillover rate was lower in treatment group than in control group (P < 0.05). Conclusion 　Renal sympathetic nerve radiofrequency ablation significantly inhibits the elevation of norepinephrine spillover rate and sympathetic nerve activity in dogs with hypertension.