中文摘要：

目的研究抗氧化剂对热打击过程中人脐动脉血管平滑肌细胞（HUASMCs）收缩反应的影响。方法将HUASMCs分为对照组、热打击组（HS组）和热打击前超氧化物歧化酶（SOD）预处理组（SOD＋HS组）,每组分别用低浓度NE（0.05mg/L）及常规浓度NE（1.0mg/L）刺激。各组细胞于41℃恒温水箱中分别培养0.5、1、1.5、2h后添加NE刺激,采用细胞表面积收缩比（%）反映细胞对NE的反应性。结果与对照组比较,无论是给予低浓度或常规浓度NE刺激,HS组细胞热打击1h时对于NE的反应性均明显增高,2h时对于NE的反应性则明显降低（P〈0.05或P〈0.01）;SOD＋HS组细胞对NE的反应性在热打击至2h后均出现明显下降（P〈0.05或P〈0.01）。对照组及HS组细胞对不同浓度NE刺激的反应性差异无统计学意义（P〉0.05）,SOD＋HS组细胞在热打击过程中对常规浓度NE的反应性明显高于对低剂量NE的反应性（P〈0.05或P〈0.01）。无论给予常规浓度或低浓度NE刺激,SOD＋HS组细胞对NE的反应性均低于HS组（P〈0.05或P〈0.01）。结论热打击过程中,HUASMCs对NE的反应性呈时相性变化。抗氧化剂在中暑早期可能可以纠正HUASMCs对NE的过反应现象,但在热打击中后期,抗氧化剂并不能改善其反应性的下降。

英文摘要：

Objective To study the change of the contractile response of human umbilical artery smooth muscle cells （HUASMCs） during the heat stress, and explore the effect of the antioxidant on the changes. Methods HUASMCs were randomly divided into control group, heat stress group, antioxidant preprocessing group. Cells were stimulated by norepinephrine （NE） at a low concentration （0.05mg/L） and at a normal concentration （1.0mg/L） and cultured in the thermostatic water bath （41℃） for 0.5, 1, 1.5 or 2h, respectively. After stimulated by NE, proportion of the cell surface area contraction was measured to reflect the contractile response of each group. Results Compared with control group, regardless of the NE concentration： in heat stress group, contractile response at 1h increased significantly （P〈0.05）, while at 2h, it was reduced significantly （P〈0.05 or 0.01）. In the antioxidant preprocessing group, the contractile response was reduced significantly from heat stress to 2h after heat stress （P〈0.05 or 0.01）. There was no statistically significant difference in contractile response between different NE concentrations in the control group and heat stress group （P〉0.05）, but in the antioxidant preprocessing group, the contractile response was more significant to the normal NE concentration than to the low NE concentration （P〈0.05 or 0.01）. Regardless of the NE concentration, the contractile response was lower in the antioxidant preprocessing group than in the heat stress group. Conclusions In the course of heat stress, the contractile response of HUASMCs presents as time-related change. The usage of antioxidant may correct the over-response of HUASMCs to NE in the early heat stress stage, but cannot correct the reduction of the contractile response in the middle and advanced stage.