The Research of Renal Denervation by Catheter Ablation on Neurogenic Hypertension of Dogs
|School||Tianjin Medical University|
|Keywords||Hypertension Kidney Renal Sympathetic Denervation nerve fibersACE2|
Objective: The hypertension models were made to study the mechanism which the Renal Sympathetic Denervation had the effects of the hypertension. To assess the validity and safety of the treatment; to investigate the effects of this treatment on kidney; to evaluate the change of the neuroendocrine indicators after this treatment; to explore the change of endothelial function after this treatment; to assess the relation among Renal Sympathetic Denervation, angiotension converting enzyme2(ACE2) and renal nerve fibers.Methods:1、Twenty-four mongrel dogs were studied as intervention groups (n=10), modeling groups (n=8) and control groups (n=6).The intervention group was made the neurogenic hypertension model, and the modeling group was only made the neurogenic hypertension model, which is used for detecting the change of angiotensin Ⅱ (Ang Ⅱ) and ACE2. The intervention group and control group received Renal Sympathetic Denervation(RSD).2、Dogs in the model group were anesthetized by administration of3%sodium pentobarbital (produced by Sigma company) and Sumianxin (produced by Military Medical Institute of Changchun) at dosage levels of30mg/kg and0.1ml/kg, respectively. Then, the dogs were placed in the supine position and the skin of the neck was disinfected using povidone. An incision was made in the neck to expose the left vagus nerve and the cervical carotid artery, and a1-2-mm-long5-0chromic catgut suture was placed around the vagus nerve. After demyelination, the vagus nerve was compressed with a carotid pulse; this model imitated the intracranial pathological environment (vascular compression of the intracranial vagus nerve without myelin). To avoid infections, intramuscular injections of gentamicin were administered for3days.3. After successfully inducing hypertension in the model group, renal denervation by using catheter ablation was performed for both the model group and control group. Dogs were anesthetized using3%sodium pentobarbital (30mg/kg) and Sumianxin (0.1ml/kg) and fixed on the operating table in the supine position. Then, the right femoral artery and the back skin was disinfected and connected to the radiofrequency ablation apparatus (IBI-1500T, produced by the IBI Company of United States); the upper limit temperature of the radiofrequency ablation instrument was fixed at60℃. After disinfecting the adjacent operation area, an8F guiding wire was inserted into the punctured right femoral artery through the guiding sheath, and the blood pressure before operation was determined. Renal angiography was performed to determine the location of the renal artery; the ablation electrode (8F ablation catheter tip, electrode length of4mm) was placed at the location of the artery; We applied discrete, radiofrequency ablations lasting up to2min each and of10watts or less to obtain up to six ablations separated both longitudinally and rotationally within each renal artery, and each dog had simultaneous bilateral renal artery denervation, the blood pressure was monitored after the process.4. We measured the blood pressure of the dogs by using an invasive blood pressure monitor (produced by Philips Company); to maintain the accuracy and stability of the experiment, an indwelling sheath was inserted in the femoral artery and connected to the blood pressure transducer (produced by Beijing Institute of Aerospace Biomedical Engineering) with the invasive blood pressure monitor. Blood pressure values were obtained at2weeks,4weeks, and10weeks after the procedure. After monitoring, the puncture point was pressed with the hand to arrest bleeding, and intramuscular injections of gentamicin were administered for3days to avoid infections.5. Blood samples were taken before and after the ablation; after centrifugation, serum samples were obtained, and to1ml of each sample,20μl of the inhibitor PMSF (containing Na2EDTA,8-hydroxyquinoline, and2-mercapto-propanol) were added. Angiotensin II concentration was detected by radioimmunoassay, and renin activity and aldosterone concentration were detected by enzyme-linked immunosorbent assay. The detection ET-1and CGRP was used by method of radiation immune method.6. The changes of angiotensin converting enzyme2:the white blood cells and tissue were taken of total dogs, form which ACE2genes were extracted. And then we observed the changes of ACE2through the RT-PCR.7. The opening blood vessels of the renal artery were removed before RSD in the modeling group and after RSD in the intervention group. The vessels were immersed in formalin and embedded in paraffin, then detected the changes of the numbers of nerve fibers in the different stages of the dogs by the sliver staining.Results:1、Blood pressure decreased significantly in both the control group and blank group after renal denervation at2weekss、4weeks、10weeks(p<0.05), while the Creatinine did not show any changes (p>0.05) 2、In intervention group, ET-1、CGRP had changed significantly(p<0.01) after remolding, compared with baseline level, and the level of ET-1、CGRP changed significantly after catheter-based renal denervation (p<0.05).3、The level of renal nerve fiber decreased compared with baseline level after catheter-based renal denervation.4、The level of ACE2was increased significantly after catheter-based renal denervation.Conelusion:1、Blood pressure decreased significantly in both the control group and blank group after renal denervation, and did not show any harmful effects of kindy.2、In intervention group, the endothelial function have improved to some degree after renal denervation, while the function of RAAS system decreased.3、The level of renal nerve fiber decreased compared with baseline level after renal denervation.4. The level of ACE2was increased significantly after renal denervation.