谷氨酰胺诱导热休克蛋白70表达对LPS休克大鼠血管反应性的影响

目的： 观察注射谷氨酰胺（Gln）诱导热休克蛋白（HSP）表达对LPS休克大鼠血管反应性的影响。方法： 健康雄性SD大鼠，随机分成对照组(n=8);LPS休克组（LPS 10 mg·kg-1 iv,n=8）;Gln 治疗组(LPS注射前1 h Gln 0.75 g·kg-1 iv,n=8)。注射LPS 6 h后静注去氧肾上腺素（PE,0.5-2.5 μg·kg-1）,观察各组大鼠平均动脉压的增加百分比。注射LPS后90 min、360 min测定血清TNF-α、IL-6和血浆MDA含量。体内实验结束后，取大鼠胸主动脉环做离体张力实验，建立PE的剂量-反应曲线并计算Emax、EC50值。检测心脏、主动脉HSP70的表达。结果： LPS休克组动物平均动脉压的平均增长率较对照组降低51.4%（P<0.05），Gln组平均动脉压对PE的反应较LPS休克组提高17.5%(P<0.05)。LPS休克组胸主动脉环对PE收缩反应的Emax和EC50显著低于对照组（P<0.05），而在Gln组的血管反应性显著高于LPS休克组(P<0.05)。Gln组心脏、主动脉HSP70的表达量显著高于LPS休克组（P<0.05），而TNF-α、IL-6及MDA水平均显著低于LPS休克组（P<0.05）。结论: 谷氨酰胺通过诱导HSP70的表达，减少炎性介质生成和抑制体内过氧化物产生，提高LPS休克血管低反应性，可能有助于休克病人的治疗。

Effect of heat shock protein 70 expression induced by glutamine on vascular hyporeactivity in rats caused by LPS

AIM: To observe the effect of heat shock protein 70(HSP70) expression induced by glutamine on Escherichia coli lipopolysaccharides(LPS)-induced vascular hyporeactivity in rats.METHODS: Twenty four healthy male Sprague-Dawley rats were randomly divided into: the control group (n=8);LPS shock group (n=8);glutamine(Gln) treated group (Gln 0.75 g·kg-1 iv,n=8).6 h after LPS shock,phenylephrine (PE,0.5-2.5 μg·kg-1 ) was applied intravenously to all groups and the percentage increase in mean arterial pressure(MAP) was detected,respectively.The concentration-response curves of aorta rings were obtained by cumulative addition of phenylephrine (PE),and PE Emax,EC50 were calculated.The blood concentration of malondialdehyde (MDA),TNF-α and IL-6 were assayed in all groups 30 min and 360 min after LPS shock,respectively.The expressions of HSP70 from heart and aorta were also assayed after 6 h LPS shock.RESULTS: The MAP level induced by PE significantly decreased by 51.4% in LPS shock group compared with the control (P<0.05).However,PE induced MAP level increased by 17.5% in Gln group compared with LPS shock group (P<0.05).Emax and EC50 to PE were significant reduced in LPS shock group compared with control group (P<0.05),but significantly improved in Gln group (P<0.05).The expressions of HSP70 from heart and aorta were much higher in Gln group than those in LPS shock group (P<0.05).The blood concentrations of TNF-α,IL-6 and MDA were much lower in Gln group than those in LPS shock group.CONCLUSION: Glutamine effectively improves α-adrenergic receptor-mediated vascular reactivity through inducing the expression of HSP 70,reducing inflammatory cytokine release and peroxide biosynthesis in LPS shock.These results suggest that glutamine have potential beneficial therapeutic effect for septic shock patients.