BACKGROUNDRenal sympathetic nerves are involved in the reflective activation of the sympathetic nervous system in circulatory control. Catheter-based renal denervation (RDN) ameliorated treatment-resistant hypertension safely, but 10%-20% of treated patients are nonresponders to radiofrequency denervation. The purpose of this study was to investigate the safety and efficiency of cryoablation for sympathetic denervation in a swine model and to explore a new way of RDN.

METHODSSeven swines randomly assigned to two groups: Renal cryoablation (CR) group and control group. The control group underwent renal angiogram only. The CR group underwent renal angiogram plus bilateral renal cryoablation. Renal angiograms via femoral were performed before denervation, after denervation and prior to the sacrifice to access the diameter of renal arterial and the pressure of aorta abdominalis. Euthanasia of the swine was performed on 28-day to access norepinephrine (NE) changes of the renal cortex and the changes of renal nerves.

RESULTSCryoablation did not induce severe complications at any time point. There was no significant change in diameter of renal artery. CR reduced systolic blood pressure (BP) from 145.50 ± 9.95 mmHg at baseline to 119.00 ± 14.09 mmHg. There was a slight but insignificant decrease in diastolic BP. The main nerve changes at 28-day consisted of necrosis with perineurial fibrosis at the site of CR exposure in conjunction with the nerve vacuolation. Compared with the control group, renal tissue NE of CR group decreased by 89.85%.

CONCLUSIONSPercutaneous catheter-based cryoablation of the renal artery is safe. CR could effectively reduce NE storing in the renal cortex, and the efficiency could be maintained 28-day at least.

Animals ; Cryosurgery ; methods ; Female ; Kidney ; innervation ; Male ; Swine ; Sympathectomy ; methods ; Treatment Outcome

The present study was aimed to investigate the roles of renal sympathetic nerve and oxidative stress in the development of foot shock-induced hypertension. Ninety rats were divided into 6 groups (the number of each group was 15): control group, foot shock group, denervation of renal sympathetic nerve group, denervation of renal sympathetic nerve + foot shock group, Tempol treatment + foot shock group, denervation of renal sympathetic nerve + Tempol treatment + foot shock group. Rats were received electrical foot shock for 14 days (2-4 mA, 75 V, shocks of 50-100 ms every 30 s, for 4 h each session through an electrified grid floor every day). Renal sympathetic ablation was used to remove bilateral renal sympathetic nerve in rats (rats were allowed to recover for one week before the beginning of the foot shock procedure). The antioxidant Tempol was injected intraperitoneally at 1 h before foot shock. Systolic blood pressure was measured at 1 h after foot shock on day 0, 3, 7, 10 and 14. Contents of thiobarbituric acid reactive substance (TBARS), renin, angiotensin II (AngII) and glutathione peroxidase (GSH-Px) in plasma were measured by ELISA after 14-day foot shock. The results showed that systolic blood pressure of foot shock group was significantly increased (P < 0.05) compared with that of control group from day 7 to day 14 of foot shock. Denervation of renal sympathetic nerve and/or Tempol treatment significantly reduced the increase of systolic blood pressure induced by foot shock. Levels of TBARS, renin and AngII in plasma were increased significantly in foot shock group compared with that of control group (P < 0.05). Plasma GSH-Px concentration was decreased in foot shock group rats compared with that of control group (P < 0.05). Denervation of renal sympathetic nerve and/or tempol treatment significantly reduced the increase in TBARS, renin, AngII levels induced by foot shock in comparison with that of foot shock group (P < 0.05), but had no effects on the reduction of GSH-Px concentration. The results suggest that renal sympathetic nerve may play an important role in the development of foot shock-induced hypertension, and renal sympathetic nerve may influence oxidative stress and directly or indirectly activate renin-angiotensin-aldosterone system, so the foot shock-induced high blood pressure may be maintained and hypertension may therefore be produced.
Animals ; Antioxidants ; pharmacology ; Blood Pressure ; Cyclic N-Oxides ; pharmacology ; Denervation ; Electric Stimulation ; Hypertension ; physiopathology ; Kidney ; innervation ; Oxidative Stress ; Rats ; Renin-Angiotensin System ; Spin Labels ; Sympathetic Nervous System ; physiology

OBJECTIVETo review the advances in studies on renal denervation.

DATA SOURCESReferences concerning renal denervation and resistant hypertension cited in this review were collected from PubMed published in English and those of renal denervation devices from official websites of device manufacturers up to January 2014.

STUDY SELECTIONArticles with keywords "renal denervation" and "resistant hypertension" were selected.

RESULTSRenal and systemic sympathetic overactivity plays an important role in pathology of hypertension as well as other diseases characterized by sympathetic overactivity. Renal denervation is a new, catheter based procedure to reduce renal and systemic sympathetic overactivity by disruption of renal sympathetic efferent and afferent nerves through radiofrequency or ultrasound energy delivered to the endoluminal surface of both renal arteries. Although several studies have shown the efficacy and safety of renal denervation in the treatment of resistant hypertension and the potential benefit of the procedure in other diseases, Symplicity HTN 3 study, the most rigorous clinical trial of renal denervation to date, failed to meet its primary endpoint. The procedure also has other limitations such as the lack of long term, efficacy and safety data and the lack of the predictors for the blood pressure lowering response and nonresponse to the procedure. An overview of current renal denervation devices holding Conformité Européenne mark is also included in this review.

CONCLUSIONSRenal denervation is a promising therapeutic approach in the management of resistant hypertension and other diseases characterized by sympathetic overactivity. In its early stage of clinical application, the efficacy of the procedure is still controversial. Large scale, blind, randomized, controlled clinical trials are still necessary to address the limitations of the procedure.

Blood Pressure ; physiology ; Denervation ; methods ; Humans ; Hypertension ; Kidney ; innervation ; Neurosurgical Procedures ; Sympathetic Nervous System ; metabolism

Denervation ; methods ; Humans ; Hypertension ; surgery ; Kidney ; innervation ; Sympathetic Nervous System ; surgery

OBJECTIVETo investigate whether brain reactive oxygen species mediate sympathoexcitation and arterial pressure elevation in DOCA-salt hypertensive rats.

METHODSDOCA-salt hypertensive model was established in male SD rats by subcutaneous injection of DOCA after uninephrectomy and drinking 1% NaCl solution for 4 weeks. The baseline mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded in the rats under mild anesthesia, and MAP changes following intravenous hexamethonium injection were observed. The responses of MAP, HR and RSNA to intracerebroventricular administration of tempol (20 µmol/L in 10 µl) were evaluated; plasma NE level was measured with ELISA, and ROS level and NAD(P)H oxidase activity in the hypothalamus were detected using chemiluminescence assay.

RESULTSMAP and plasma NE levels were significantly increased in DOCA-salt rats as compared with those in the control group (P<0.01). In DOCA-salt hypertensive rats, intravenous hexamethonium injection induced a blood pressure reduction 240% of that in control rats, and significantly increased the levels of superoxide anion and NAD(P)H oxidase activity in the hypothalamus. Intracerebroventricular microinjection of tempol also resulted in more significant changes of MAP, HR and RSNA in DOCA-salt rats than in the control group (P<0.01).

CONCLUSIONSympathoexcitation due to increased NAD(P)H oxidase-derived ROS levels in the hypothalamus may mediate arterial pressure elevation in DOCA-salt hypertensive rats.

Animals ; Antioxidants ; Arterial Pressure ; Blood Pressure ; Brain ; metabolism ; Cyclic N-Oxides ; pharmacology ; Desoxycorticosterone ; Desoxycorticosterone Acetate ; Disease Models, Animal ; Heart Rate ; Hypertension ; Kidney ; innervation ; Male ; NADPH Oxidases ; metabolism ; Rats ; Rats, Sprague-Dawley ; Reactive Oxygen Species ; metabolism ; Sodium Chloride ; Spin Labels ; Superoxides ; metabolism ; Sympathetic Nervous System

OBJECTIVE: To observe the changes of blood pressure and S-100B, neuron specific enolase (NSE) protein in hypertensive dogs with high fat diet after catheter-based renal sympathetic denervation. METHODS: Twelve Beagles were divided into an interventional group (n=6) and a sham-operation group (n=6). After baseline measurements, the Beagles were fed with lard oil for 3 months. After 3 months, the interventional group had renal sympathetic denervation by percutaneous catheter based radiofrequency ablation and the control group had renal angiography. The blood pressure, plasma S-100B, and NSE before the operation and 3 days, 1 week, 2 weeks, 1 month, 2 months and 3 months after the operation were measured. RESULTS: The dogs had significantly higher levels of systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MBP) compared to its baselines (P<0.05). The SBP, DBP and MBP in the interventional group were significantly lower than those in the control group 1 month and 3 months after the operation (P<0.05). Three months after the operation, renal angiography in all dogs revealed no sign of renal artery stenosis. Plasma S-100B and NSE expression in the interventional group were higher than those in the control group 3 days, 1 week and 2 weeks after the operation (P<0.05). CONCLUSION Renal sympathetic denervation can significantly reduce the SBP, DBP and MBP in hypertensive dogs. The plasma S-100B and NSE may be used as indicators for assessment of renal nerve injury after renal sympathetic denervation.
Animals ; Blood Pressure ; Catheter Ablation ; Dogs ; Hypertension ; metabolism ; Kidney ; innervation ; surgery ; Phosphopyruvate Hydratase ; metabolism ; S100 Calcium Binding Protein beta Subunit ; metabolism ; Sympathectomy

Adult ; Humans ; Hypertension ; surgery ; Kidney ; innervation ; Kidney Failure, Chronic ; surgery ; Male ; Sympathectomy ; methods

Adult ; Denervation ; methods ; Humans ; Kidney ; innervation ; Male ; Tachycardia, Ventricular ; surgery

Catheter Ablation ; methods ; Humans ; Hypertension, Renal ; surgery ; Kidney ; innervation ; surgery ; Sympathectomy

OBJECTIVE: To investigate the impact of renal denervation on the blood pressure, plasma renalase content and expression of renalase and tyrosine hydroxylase (TH) in the idney of spontaneous hypertensive (SH) rats and to explore the role of renal denervation in lowering the blood pressure. METHODS: SH rats were randomly assigned into a baseline group, a surgery (renal denervation) group, a sham group and a control group (n=48). WKY rats matched in age (n=12) served as a baseline control group. All rats were housed until 12 weeks old. Then, the rats in the baseline group and the WKY group were sacrificed whose blood and kidney were collected for examination. In the renal denervation group, the sham group and the control group, the blood pressure was monitored continuously. One week and 6 weeks after the renal denervation, 6 rats in each group were sacrificed whose blood and kidney were collected. ELISA was employed to measure the plasma renalase and Western blot assay done to detect the expression of TH and renalase in the kidney. RESULTS: Compared with WKY rats, blood pressure significantly increased and TH protein expression markedly elevated (P<0.05) in SH rats in the baseline group, but plasma renalase content and protein expression of renalase in the kidney dramatically reduced (P<0.05). One week after the surgery, the mean arterial pressure and TH protein expression in the surgery group were lowered compared with the baseline group and dramatically reduced compared with the sham group and the control group (P<0.05). In the surgery group, the renalase level was markedly increased compared with the baseline group, the sham group, and the control group (P<0.05). Six weeks after the renal denervation, the mean arterial pressure and TH level in the surgery group were significantly increased but the renalase content and expression markedly reduced compared with those 1 week, but there were no marked differences among the surgery group, the sham group, and the control group (P>0.05). No pronounced differences in the above variables were found between the sham group and the control group at any time point (P>0.05). CONCLUSION Renal denervation can lower the blood pressure, which may attribute to the suppression of sympathetic nerves, increase in plasma renalase content and renalase expression in the kidney.
Animals ; Blood Pressure ; physiology ; Hypertension ; surgery ; Kidney ; enzymology ; innervation ; Male ; Monoamine Oxidase ; blood ; metabolism ; Rats ; Rats, Inbred SHR ; Sympathectomy ; methods ; Sympathetic Nervous System ; physiopathology ; Tyrosine 3-Monooxygenase ; metabolism