Niederberger M, Ginès P, Martin P Y, St John J, Woytaszek P, Xu L, Tsai P, Nemenoff R A, Schrier R W
Department of Medicine, University of Colorado School of Medicine, Denver, USA.
Hepatology. 1998 Jan;27(1):42-7. doi: 10.1002/hep.510270108.
Indirect evidence suggests that the renal and vascular production of prostaglandins is increased in cirrhosis with ascites. However, the activity of the enzymes regulating the prostaglandin pathway has not been investigated in cirrhosis. The aim of the current study was to determine the activity of phospholipase A2 (PLA2), the key enzyme in the regulation of prostaglandin synthesis, in kidney and vascular tissue obtained from rats with carbon tetrachloride-induced cirrhosis and ascites (n = 9) and control rats (n = 6). PLA2 activity was assayed in vitro using [14C]arachidonyl-phosphatidylcholine (PC) and [14C]arachidonyl-phosphatidylethanolamine (PE) as substrates in the presence of Ca2+. Kidneys from cirrhotic rats had significantly higher PLA2 activity compared with control rats, with both PC and PE (35 +/- 5 and 40 +/- 6 vs. 21 +/- 2 and 26 +/- 3 pmol/mg/min, respectively; P < .05 for both). PLA2 activity was increased in the renal cortex as well as in the renal medulla. Fractionation of the kidney extracts by Mono-Q anion-exchange chromatography showed that the elution position of PLA2 activity corresponded to the cytosolic PLA2 isoform (cPLA2). Increased amounts of cPLA2 protein were found in kidney extracts immunoblotted with an anti-cPLA2 antibody However, reverse-transcriptase polymerase chain reaction (RT-PCR) analysis did not detect any difference in cPLA2 mRNA. PLA2 activity was also higher in aortic tissue from cirrhotic rats than in controls (PC 38 +/- 5 vs. 26 +/- 1 and PE 66 +/- 8 vs. 41 +/- 3 pmol/mg/min; P < .05 for both). Incubation of renal and aortic extracts from cirrhotic rats with anti-cPLA2 antibody reduced PLA2 activity by 64% and 88%, respectively. In conclusion, PLA2 activity is increased in kidneys and vascular tissue from cirrhotic rats with ascites. This can be accounted for by an induction of cPLA2, which would mediate, at least in part, the increased renal and vascular production of prostaglandins in cirrhosis.
间接证据表明，肝硬化腹水患者肾脏和血管中前列腺素的生成增加。然而，尚未对肝硬化患者中调节前列腺素途径的酶的活性进行研究。本研究的目的是测定从四氯化碳诱导的肝硬化腹水大鼠（n = 9）和对照大鼠（n = 6）获取的肾脏和血管组织中磷脂酶A2（PLA2）的活性，PLA2是调节前列腺素合成的关键酶。在Ca2+存在的情况下，使用[14C]花生四烯酰磷脂酰胆碱（PC）和[14C]花生四烯酰磷脂酰乙醇胺（PE）作为底物，体外测定PLA2活性。与对照大鼠相比，肝硬化大鼠的肾脏具有显著更高的PLA2活性，PC和PE均如此（分别为35±5和40±6对21±2和26±3 pmol/mg/min；两者P均<.05）。肾皮质和肾髓质中的PLA2活性均增加。通过Mono-Q阴离子交换色谱对肾脏提取物进行分级分离表明，PLA2活性的洗脱位置对应于胞质型PLA2同工型（cPLA2）。在用抗cPLA2抗体进行免疫印迹的肾脏提取物中发现cPLA2蛋白量增加。然而，逆转录酶聚合酶链反应（RT-PCR）分析未检测到cPLA2 mRNA有任何差异。肝硬化大鼠主动脉组织中的PLA2活性也高于对照组（PC 38±5对26±1，PE 66±8对41±3 pmol/mg/min；两者P均<.05）。用抗cPLA2抗体孵育肝硬化大鼠的肾脏和主动脉提取物分别使PLA2活性降低64%和88%。总之，肝硬化腹水大鼠的肾脏和血管组织中PLA2活性增加。这可以通过cPLA2的诱导来解释，cPLA2至少部分介导了肝硬化中肾脏和血管前列腺素生成的增加。
