Deaciuc I V, Spitzer J A
Department of Physiology, Louisiana State University Medical Center, New Orleans 70112.
Am J Physiol. 1989 Nov;257(5 Pt 2):R1232-40. doi: 10.1152/ajpregu.1989.257.5.R1232.
The purpose of this study was to investigate possible alterations induced by sepsis and endotoxicosis in the late phase of Ca2+-dependent signaling in rat liver. Hepatocytes isolated from septic or chronically endotoxin (ET)-treated rats were labeled with [32P]H3PO4 and stimulated with various agents. Proteins were resolved by one-dimensional polyacrylamide gel electrophoresis and autoradiographed. Vasopressin (VP)- and phenylephrine (PE)-induced responses were attenuated in both septic and ET-treated rats for cytosolic and membrane proteins compared with their respective controls. Glucagon and 12-O-myristate phorbol-13-acetate (TPA) affected only the phosphorylation of membrane proteins. Glucagon-induced changes in the phosphorylation of membrane proteins were affected by both sepsis and endotoxicosis, whereas TPA-stimulated phosphorylation was lowered only in endotoxicosis. Response to the Ca2+ ionophore A23187 was depressed in septic rats for cytosolic proteins. The phosphorylation of two cytosolic proteins, i.e., 93 and 61 kDa (previously identified as glycogen phosphorylase and pyruvate kinase, respectively), in response to VP, PE, and A23187 was severely impaired by endotoxicosis and sepsis. TPA did not affect the phosphorylation state of these two proteins. The results show that sepsis and endotoxicosis produce perturbations of the phosphorylation step in Ca2+ transmembrane signaling. Such changes can explain alterations of glycogenolysis and gluconeogenesis associated with sepsis and endotoxicosis.
本研究的目的是调查败血症和内毒素血症在大鼠肝脏中Ca2+依赖性信号传导后期所引起的可能变化。从败血症大鼠或长期接受内毒素（ET）处理的大鼠中分离出的肝细胞用[32P]H3PO4标记，并用各种试剂刺激。蛋白质通过一维聚丙烯酰胺凝胶电泳分离并进行放射自显影。与各自的对照组相比，败血症大鼠和ET处理的大鼠中，血管加压素（VP）和去氧肾上腺素（PE）诱导的细胞溶质和膜蛋白反应均减弱。胰高血糖素和12-O-十四烷酰佛波醇-13-乙酸酯（TPA）仅影响膜蛋白的磷酸化。败血症和内毒素血症均影响胰高血糖素诱导的膜蛋白磷酸化变化，而TPA刺激的磷酸化仅在内毒素血症中降低。败血症大鼠中，细胞溶质蛋白对Ca2+离子载体A23187的反应减弱。内毒素血症和败血症严重损害了两种细胞溶质蛋白（即93 kDa和61 kDa，以前分别鉴定为糖原磷酸化酶和丙酮酸激酶）对VP、PE和A23187的磷酸化反应。TPA不影响这两种蛋白的磷酸化状态。结果表明，败血症和内毒素血症会导致Ca2+跨膜信号传导中磷酸化步骤的紊乱。这些变化可以解释与败血症和内毒素血症相关的糖原分解和糖异生的改变。
