Department of Physiology, College of Medicine, Nanchang University, Nanchang, China.
J Surg Res. 2012 Dec;178(2):1015-21. doi: 10.1016/j.jss.2012.07.061. Epub 2012 Aug 14.
Extensive experimental and clinical studies have shown that ischemic preconditioning (IP) can produce protective effects during hepatic ischemia reperfusion (I/R) injury. Our recent studies indicate that rat liver I/R injury is related to an abnormal increase in leukotriene (LT) C4 production. However, the mechanisms underlying IP actions on LTC4 generation during hepatic I/R injury remain to be explored.
We randomly divided adult male Sprague-Dawley rats into sham (control), I/R, and IP groups (n = 6). We subjected rat liver to 60 min partial hepatic ischemia followed by 5 h reperfusion with saline administered intravenously. We detected protein expression of LTC4 synthase (LTC4S) with Western blot, and measured LTC4 synthesis enzymes' activities and content by reverse-phase high-performance liquid chromatography. We assessed tissue injury using serum aspartate aminotransferase and aspartate aminotransferase activities and histologic changes. We examined liver tissue glutathione levels by a biochemical method.
Ischemic preconditioning markedly decreased LTC4 content, reduced LTC4S protein expressions, and inhibited LTC4 synthesis enzymes' activities in rat liver compared with the I/R group (P < 0.05). We also observed a decline in serum alanine aminotransferase and aspartate aminotransferase activities (P < 0.05), together with hepatic tissue glutathione elevation (P < 0.05) in the IP groups. Positive expression of LTC4S on hepatocytes and sinusoidal endothelial cells in the IP group was significantly lower than that in the I/R group.
These findings demonstrate that reduced LTC4 production by IP treatment during hepatic I/R injury could partially result from the down-regulation of LTC4S protein expression and the depression of LTC4 synthesis enzyme activity. They suggest that the beneficial effects of IP may be involved in repression of LTC4 generation during hepatic I/R injury.
大量的实验和临床研究表明，缺血预处理（IP）可以在肝缺血再灌注（I/R）损伤中产生保护作用。我们最近的研究表明，大鼠肝 I/R 损伤与白三烯（LT）C4 产生的异常增加有关。然而，IP 对肝 I/R 损伤期间 LTC4 生成的作用机制仍有待探讨。
我们将成年雄性 Sprague-Dawley 大鼠随机分为假手术（对照）、I/R 和 IP 组（n = 6）。我们对大鼠肝脏进行 60 分钟部分肝缺血，然后静脉注射生理盐水进行 5 小时再灌注。我们用 Western blot 检测 LTC4 合酶（LTC4S）的蛋白表达，并通过反相高效液相色谱法测量 LTC4 合成酶的活性和含量。我们通过血清天冬氨酸氨基转移酶和天冬氨酸氨基转移酶活性以及组织学变化来评估组织损伤。我们通过生化方法检测肝组织谷胱甘肽水平。
与 I/R 组相比，IP 组大鼠肝组织中 LTC4 含量明显降低，LTC4S 蛋白表达降低，LTC4 合成酶活性受到抑制（P < 0.05）。我们还观察到 IP 组血清丙氨酸氨基转移酶和天冬氨酸氨基转移酶活性下降（P < 0.05），肝组织谷胱甘肽水平升高（P < 0.05）。IP 组肝细胞和窦内皮细胞上 LTC4S 的阳性表达明显低于 I/R 组。
这些发现表明，在肝 I/R 损伤期间，IP 治疗减少 LTC4 的产生可能部分是由于 LTC4S 蛋白表达下调和 LTC4 合成酶活性抑制所致。这表明 IP 的有益作用可能涉及在肝 I/R 损伤期间抑制 LTC4 的产生。
