Investigation of the mechanism underlying the antihypertensive effect of catheter-based radiofrequency renal sympathetic denervation in hypertensive dogs.

The present study aimed to assess the antihypertensive efficacy and safety of catheter-based radiofrequency renal sympathetic denervation (RSD) in hypertensive dogs. Furthermore, the study investigated the possible antihypertensive mechanism of radiofrequency RSD through measuring the postoperative serum concentrations of angiotensin II (AngII), nicotinamide adenine dinucleotide phosphate oxidase (NADPH-ox), malondialdehyde (MDA), nitric oxide (NO) and endothelial NO synthase (eNOS). A total of 12 beagles were randomly divided into the surgery (n=6) and the sham-surgery groups (n=6). The hypertension model was established using a high-fat diet. The surgery group received catheter-based radiofrequency RSD, while the sham-surgery group only received renal arteriography. Blood pressure was measured prior to the surgery and 3 days, 1 and 2 weeks, and 1, 2 and 3 months after the surgery. The serum concentrations of AngII, NADPH-ox, MDA, NO and eNOS were measured prior to the surgery and 1 week, and 1 and 3 months after the surgery. Following the establishment of the model, the systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) of the surgery and the sham-surgery groups were all significantly increased above the baseline (P<0.05), but there was no significant difference between the two groups. SAP, DAP and MAP in the surgery group at 1 and 3 months after the surgery were significantly decreased compared to the levels measured prior to the surgery and those in the sham-surgery group (P<0.05). Three months after the surgery, the serum creatinine level was normal and renal arteriography did not show renal artery stenosis. Compared to those measured prior to the surgery, the concentrations of serum AngII, NADPH-ox and MDA in the surgery group at 1 week, and 1 and 3 months after the surgery were decreased, while the concentrations of serum NO and eNOS were increased (P<0.05). The above indicators measured at the same time points demonstrated statistically significant differences between the surgery and the sham-surgery groups (P<0.05). In conclusion, catheter-based radiofrequency RSD may inhibit the renin-angiotensin system and the oxidative stress response, as well as improve vascular endothelial function, thus significantly reducing blood pressure through the reduction of sympathetic activity in hypertensive dogs.