严重烫伤大鼠早期心肌抑制对肝肾肠损害的影响

Influence of myocardial inhibition on injury to liver, kidney and intestine at early stage in rat with severe scald

目的了解严重烫伤大鼠早期心肌抑制对肝、肾、肠损害及血流灌注的影响。方法将32只Wistar大鼠按随机数字表分为假伤组、普萘洛尔组、烫伤对照组和烫伤＋普萘洛尔组，每组8只。各组大鼠腹腔注射10g／L戊巴比妥钠（30mg／kg）麻醉后，假伤组、普萘洛尔组置于37℃水中18s致假伤，其余2组置于97℃水浴中18S，造成30％TBSAⅢ度烫伤。伤后30min按Parkland公式腹腔注射复方乳酸钠林格液（4mL·kg^-1·1％TBSA^-1）。普萘洛尔组、烫伤＋普萘洛尔组补液的同时静脉注射普萘洛尔0．75mg／kg。伤后6h以多道生理信号采集仪检测大鼠动脉收缩压（SBP）、动脉舒张压（DBP）、平均动脉压（MAP）以及左心室收缩压（LVSP）、左心室舒张末期压（LVEDP）、左心室压力最大上升／下降速率（±dp／dtmax）；以激光多普勒血流仪检测肝、肾、肠血流量；同时抽取大鼠静脉血检测血清心肌肌钙蛋白I（cTnI）、总胆汁酸（TBA）、β2-微球蛋白（β2-MG）浓度和二胺氧化酶（DAO）活性。结果普萘洛尔组除LVEDP外，SBP、DBP、MAP、LVSP、-dp／dtmax均低于假伤组（P〈0．05）。烫伤对照组与假伤组比较，心肌力学指标均下降（P〈0．05）。烫伤＋普萘洛尔组与烫伤对照组比较，各项心肌力学指标均明显下降（P〈0．05）。与假伤组比较，烫伤对照组肝、肾、肠血流量显著降低（P〈0．05）；与烫伤对照组比较，烫伤＋普萘洛尔组肝、肾、肠血流量降低（P〈0．05）。烫伤对照组血清cTnI、TBA、β2-MG和DAO值分别为（4．86±0．29）μg／L、（83．6±18．2）μmol／L、（2．75±0．19）mg／L、（1．45±0．09）×10^3U／L，均高于假伤组[（1．73±0．09）μg／L、（24．5±2．4）μmol／L、（1．15±0．18）mg／L、（0．87±0．13）×10^3U／L，P〈0．05]；与烫伤对照组比较，烫伤＋普萘洛尔组血清cTnI（5．95±0．42）μg／L、TBA（125．8±21．3）μmol／L、β2-MG（3．25±0．17）mg／L、DAO（1．83±0．13）×10^3U／L均明显升高（P〈0．05）。结论严重烫伤大鼠早期心肌抑制能加剧肝、肾、肠损害，提示“休克心”可能是严重烧伤后早期肝、肾、肠血流量减少和损害的启动因素之一。

Objective To investigate the influence of myocardial inhibition on injury to liver, kidney and intestine and blood perfusion at early stage in rat with severe burn. Methods Thirty-two healthy male Wistar rats were enrolled in the study and randomly divided into sham scald, propranolol, scald control and scald ＋ propranolol groups, with 8 rats in each group. After intraperitoneal injection of 10 g/L pentobarbital sodium for anesthesia, rats of the former two groups were sham scalded in a water bath of 37 ℃ for 18 s, while the latter two groups were inflicted with 30% TBSA full-thickness scald in a 97 ℃ water bath for 18 s. Rats were resuscitated with Ringer＇s lactate solution （4 mL .kg^-1.1%TBSA^-1 , i. p. ） following the Parkland formula 30 mins after the injury. At the same time, rats in propranolol and scald ＋ propranolol groups received propranolol 0.75 mg/kg intravenously. After 6 hours, parameters of myocardiac mechanics （SBP, DBP, MAP, LVSP, LVEDP, ± dp/dt max） were recorded by the multiple channel physiological signal collecting and processing system; blood flow of liver, kidney and intestine were detected with the laser doppler flowmetry; the serum contents of cTnI, TBA, beta2-MG and DAO were determined for reflecting injuries to the heart, liver, kidney and intestine, respectively. Results Myocardiac mechanics parameters, with the exception of LVEDP, were decreased in proprauolol group as compared with those in sham group （ P 〈0.05）. All＇myocardiae mechanics parameters in burn control group were lower than those in sham group and higher than those in burn ＋ propranolol group （ P 〈 0.05）. Blood flow of organs showed similar changes in above-mentioned 3 groups （ P 〈 0. 05 ）. Organ damages as shown in burn control group [ cTnI （4.86 ±0.29） μg/L, TBA （83.6 ±18.2）μmol/L, β2-MG （2.75 ±0. 19） mg/L, DAO （1.45±0.09） × 10^3 U/L] were more serious than those in sham control group [ cTnI （1.73 ± 0.09）μg/L, TBA （24.5 ± 2.4） μmol/L,β2-MG （1.15 ±0.18） mg/L, DAO （0.87 ±0.13） × 10^3U/L] , and less serious than those in scald ＋ propranolol group [ cTnI 5.95 ± 0.42 μg/L, TBA 125.8 ± 21.3 μmol/L, β2-MG 3.25 ±0. 17 mg/L, DAO （ 1.83±0.13 ） ×10^3 U/L ] （ P 〈 0.05 ）. Conclusions Propranolol can aggravate injury to the liver, kidney and intestine at early stage in rat with severe burn, suggesting that ＂ shock heart＂ may be one of initial factors in lowering blood flow to the organs, thus inducing injury to them.