[ ABSTRACT] AIM: To evaluate the guiding effect of high-frequency stimulation ( HFS) on renal denervation ( RDN) , and to compare the similarities and differences of blood pressure changes at the time of electrical stimulation and radiofrequency ablation .METHODS:A total of 6 Kunming dogs were included in this study .Renal artery abnormalities were excluded by angiography .High-frequency stimulation and radiofrequency ablation were performed at the same sites from distal to proximal segments of the renal artery .Invasive blood pressure ( BP) was recorded during the whole proce-dure.The change of the blood pressure was analyzed .HE and Masson staining was adopted to detect the structural changes in the wall of the renal artery and surrounding tissues .The immumohistochemical staining for tyrosine hydroxylase ( TH) was used to observe the renal nerve damage after ablation .RESULTS: Electrical stimulation and radiofrequency ablation were delivered in a total of 50 sites.The BP increasing response was induced at 34%sites (n=17), while the rest sites (66%, n=33) had no response.Compared with the baseline , HFS caused the increases in systolic BP of (0.34 ±3.38), (0.41 ±3.04), (10.47 ±5.73), (13.27 ±3.63), (10.17 ±1.87) and (0.78 ±1.87) mmHg in 6 serial 20 s time segments during 120 s of HFS at positive BP response sites .Similarly, the increases in systolic BP by (-0.88 ±3.44) , (-1.64 ±3.47), (13.17 ±3.12), (12.82 ±3.21), (9.50 ±2.68) and ( -6.09 ±2.21) mmHg were observed dur-ing 120 s of ablation procedure at the same sites in 6 serial 20 s time segments .At non-responding sites , HFS and ablation failed to cause a significant increase in systolic BP .The mean area of nerves in the response sites was ( 0.51 ±0.28 ) mm2, whereas that in non-response sites was (0.09 ±0.06) mm2(P<0.01).The average absorbance values of TH in re-nal nerves at ablation and non-ablation sites were 0.031 ±0.015 and 0.085 ±0.018 ( P <0.01 ) , respectively . CONCLUSION:Renal sympathetic nerves can be effectively mapped by HFS .Radiofrequency ablation guided by HFS is valid to injure sympathetic nerves around renal artery .

AIM:To investigate the effect of renal denervation ( RDN) by radiofrequency catheter ablation on the expression of aquaporins ( AQP) in dog kidneys .METHODS:Adult Chinese Kunming dogs ( n=12 ) were randomly divided into RDN group and control group (6 for each group).The dogs in RDN group underwent bilateral RDN using ra-diofrequency catheter ablation , and radiofrequency catheter was positioned in bilateral renal artery without ablation in con -trol group.The levels of norepinephrine (NE) and AQP1~3 in the renal tissues were detected 1 month after RDN, and blood pressure (BP) measurements were performed at baseline and 1 month after RDN.RESULTS: The level of NE in RDN group was significantly lower than that in control group (P<0.01).The expression of AQP1~3 in the renal cortex and medulla was lower in RDN group than that in control group .RDN also caused a substantial BP reduction (P<0.05). CONCLUSION:RDN substantially decreases the tissue levels of NE and AQP in dog kidneys , and also decreases BP sig-nificantly , which might be involved in the mechanism of BP reduction by RDN .Renal sympathetic nerve plays an excitatory role in the regulation of AQP in the kidney.

Objective To investigate the target blood pressure level of restrictive fluid resuscitation in patients with traumatic hemorrhagic shock. Methods Sixty patients with traumatic hemorrhagic shock admitted to the First Affiliated Hospital of Bengbu Medical College from January 2016 to December 2018 were enrolled. All patients were resuscitated with sodium acetate ringer solution after admission. According to the difference of mean arterial pressure (MAP) target, the patients were divided into low MAP (60 mmHg ≤ MAP < 65 mmHg, 1 mmHg = 0.133 kPa), middle MAP (65 mmHg ≤ MAP < 70 mmHg) and high MAP (70 mmHg ≤ MAP < 75 mmHg) groups by random number table using the admission order with 20 patients in each group. Those who failed to reach the target MAP after 30-minute resuscitation were excluded and supplementary cases were deferred. The restrictive fluid resuscitation phase was divided into three phases: before fluid resuscitation, liquid resuscitation for 30 minutes and 60 minutes. The most suitable resuscitation blood pressure level was further speculated by monitoring the inflammatory markers and hemodynamics in different periods in each group of patients. Pearson correlation analysis was used to detect the correlation of variables. Results Before fluid resuscitation, there was no significant difference in hemodynamics or expressions of serum cytokines among the three groups. Three groups of patients were resuscitated for 30 minutes to achieve the target blood pressure level and maintain 30 minutes. With the prolongation of fluid resuscitation time, the central venous pressure (CVP), cardiac output (CO) and cardiac index (CI) were increased slowly in the three groups, and reached a steady state at about 30 minutes after resuscitation, especially in the high MAP group and the middle MAP group. The expressions of serum inflammatory factors in the three groups were gradually increased with the prolongation of fluid resuscitation time. Compared with the low MAP group and the high MAP group, after 30 minutes of resuscitation the middle MAP group was superior to the other two groups in inhibiting the expressions of pro-inflammatory factors tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and promoting anti-inflammatory factors IL-10 [TNF-α mRNA (2-ΔΔCt):0.21±0.13 vs. 0.69±0.34, 0.57±0.35; IL-6 mRNA (2-ΔΔCt): 0.35±0.31 vs. 0.72±0.39, 0.59±0.42; IL-10 mRNA (2-ΔΔCt): 1.25±0.81 vs. 0.61±0.46, 0.82±0.53; all P < 0.05], but there was no significant difference in promoting the expression of IL-4 mRNA among three groups. At 60 minutes of resuscitation, compared with the low MAP group and the high MAP group, the middle MAP group could significantly inhibit the expressions of TNF-α, IL-6 and promote IL-10 [TNF-α mRNA (2-ΔΔCt): 0.72±0.35 vs. 1.05±0.54, 1.03±0.49; IL-6 mRNA (2-ΔΔCt): 0.57±0.50 vs. 1.27±0.72, 1.01±0.64; IL-10 mRNA (2-ΔΔCt): 1.41±0.90 vs. 0.81±0.48, 0.94±0.61; all P < 0.05]. Compared with the high MAP group, the middle MAP group had significant differences in promoting the expression of IL-4 mRNA (2-ΔΔCt: 1.32±0.62 vs. 0.91±0.60, P < 0.05). There was no significant difference in serum cytokine expressions at different time points of resuscitation between the low MAP group and the high MAP group (all P > 0.05). Correlation analysis showed that there was a strong linear correlation between MAP and mRNA expressions of TNF-α, IL-6, IL-10 in the middle MAP group (r value was 0.766, 0.719, 0.692, respectively, all P < 0.01), but had no correlation with IL-4 (r = 0.361, P = 0.059). Fitting linear regression analysis showed an increase in 1 mmHg per MAP, the expression of TNF-α mRNA increased by 0.027 [95% confidence interval (95%CI) = 0.023-0.031, P < 0.001], IL-6 mRNA increased by 0.021 (95%CI = 0.017-0.024, P < 0.001), and IL-10 mRNA increased by 0.049 (95%CI = 0.041-0.058, P < 0.001). Conclusions When patients with traumatic hemorrhagic shock received restrict fluid resuscitation at MAP of 65-70 mmHg, the effect of reducing systemic inflammatory response and improving hemodynamics is better than the target MAP at 60-65 mmHg or 70-75 mmHg. It is suggested that 65-70 mmHg may be an ideal target MAP level for restrictive fluid resuscitation.