Effects And Mechanism Of Radiofrequency Ablation Of Renal Sympathetic Nerve On Renal Sympathetic Neurotransmitters Hypertensive Canine

Objectives:1. To observe levels of plasma norepinephrine (NE), and renal sympathetic neurotransmitter NE, neuropeptide Y(NPY) and catestatin (CST) in obesity-related hypertensive canine model, and the effects of radiofrequency ablation of renal sympathetic nerve(RDN) on blood pressure, the above-metioned neurotransmitters. And analysize the correlation between the neurotransmitters and blood pressure.2. To observe levels of renal angiotensin converting enzyme2(ACE2) angiotensin (1-7)(Ang1-7)-Mas axis, and the effects of RDN on this axis. Then analysize the correlation between the axis and blood pressure.3. Study the effects of NE on ACE2, Ang1-7and Mas expression in renal proximal tubular epithelial cells (HK-2).Methods:1.The obesity-related hypertensive canine model was built by high-fat diet and the surgery group was given the radiofrequency ablation of renal sympathetic nerve, renal arteriography only for sham surgery group, control group of the rest. Detecte the heart rate, weight, blood pressure, and plasma NE in0month, modeling after preoperative and postoperative6months.6months later, dogs were sacrificed after RDN; high performance liquid chromatography method was used for the determination the level of NE; PCR, Western Blot and immunohistochemical determination were applied to detect the mRNA and protein level of NPY, ACE2, Mas; ELISA for determination the CST and Ang (1-7) concentration. Then observe the difference of these indicators between the obesity-related hypertensive group and the control group, the surgery group and sham surgery group.2.Cultured HK-2cells, using the NE (10-8～10-4mol/L), set the buffer blank control interventions24hours, PCR and Western blot assay ACE2, Mas mRNA and protein expression, ELISA determination of the concentration of Ang(1-7). Compare the difference of these indicators between the intervention group and the control group.Results:1. The canine model of obesity-related hypertension SBP, DBP, MAP levels were significantly higher than those in the control group (P<0.05).6months after surgery, SBP, DBP and MAP levels of the surgery group were significantly lower than the sham surgery group (P<0.05).2. Canine obesity-related hypertension plasma NE levels were significantly higher with the control group (P<0.05).6months after surgery plasma and renal NE levels in the surgery group were significantly lower than the sham surgery group (P<0.05).3groups NPY, CST mRNA and protein expression did not differ (P>0.05). NE levels in plasma and kidney were positively correlated with SBP (P<0.05), while NPY, CST and SBP was no significantly correlation (P>0.05).3.6months after surgery, renal ACE2, Mas mRNA and protein, Ang (1-7) in the surgery group were significantly higher than the sham surgery group (P>0.05). Renal ACE2, Mas mRNA and protein, Ang (1-7) in sham surgery group were significantly lower than the control group (P<0.05). Renal ACE2, Ang (1-7) and Mas were negatively correlated with SBP (P<0.05).4. In HK-2cells, moderate and high concentrations of NE (10-6mol/L～10-4mol/L) reduced ACE2and Mas mRNA expression as a dose-dependent manner, and it reduced Ang (1-7) the expression as well (P<0.05); high concentrations of NE (10-4mol/L) inhibited ACE2and Mas protein level (P<0.05).Conclusions:1. Blood pressure, with plasma and NE increased significantly in obesity-related hypertension canine, while renal NPY, CST unchanged; RDN lowered blood pressure, plasma and renal NE, but has no effects on renal NPY and CST. NE was positively correlated with SBP.2. The renal ACE2, Ang (1-7) and Mas expression decreased significantly in obesity related-hypertension canine, and radiofrequency catheter ablation of renal sympathetic nerves increased ACE2-Ang (1-7)-Mas axis.3. High concentrations of NE lowered ACE2-Ang (1-7)-Mas axis level in HK-2cells.