P C Kuo1, K Y Abe. 1. Department of Surgery, Stanford University Medical Center, California, USA.
Abstract
BACKGROUND & AIMS: Nitric oxide modifies free radical-mediated cell processes in multiple in vivo and in vitro systems. The aim of this study was to determine the role of hepatocyte production of NO in oxidative injury. METHODS: Rat hepatocytes in primary culture were incubated with 1,2,3-benzenetriol, a source of superoxide. Interleukin (IL) 1 was added to induce NO synthesis. Injury was determined by aspartate aminotransferase (AST), malondialdehyde (MDA), and glutathione (GSH) levels. RESULTS: Benzenetriol-induced injury increased AST and MDA levels and decreased GSH levels in control and IL-1-treated cells. Inhibition of NO synthesis in IL-1-treated cells significantly increased AST and MDA production while enhancing GSH depletion. In the presence of superoxide dismutase or S-nitroso-albumin, an exogenous source of NO, injury was decreased or abolished. NO production was significantly increased with oxidative stress. In benzenetriol-induced injury in IL-1-stimulated hepatocytes, reverse-transcription polymerase chain reaction showed significantly increased levels of inducible NO synthase messenger RNA, whereas immunoblot analysis showed similarly increased levels of inducible NO synthase protein. CONCLUSIONS: In this rat hepatocyte model of IL-1/benzenetriol-mediated injury, NO, derived from endogenous synthesis or an exogenous donor, is protective. Oxidative stress may have a role in the transcriptional control of NO synthesis.
BACKGROUND & AIMS:Nitric oxide modifies free radical-mediated cell processes in multiple in vivo and in vitro systems. The aim of this study was to determine the role of hepatocyte production of NO in oxidative injury. METHODS:Rat hepatocytes in primary culture were incubated with 1,2,3-benzenetriol, a source of superoxide. Interleukin (IL) 1 was added to induce NO synthesis. Injury was determined by aspartate aminotransferase (AST), malondialdehyde (MDA), and glutathione (GSH) levels. RESULTS:Benzenetriol-induced injury increased AST and MDA levels and decreased GSH levels in control and IL-1-treated cells. Inhibition of NO synthesis in IL-1-treated cells significantly increased AST and MDA production while enhancing GSH depletion. In the presence of superoxide dismutase or S-nitroso-albumin, an exogenous source of NO, injury was decreased or abolished. NO production was significantly increased with oxidative stress. In benzenetriol-induced injury in IL-1-stimulated hepatocytes, reverse-transcription polymerase chain reaction showed significantly increased levels of inducible NO synthase messenger RNA, whereas immunoblot analysis showed similarly increased levels of inducible NO synthase protein. CONCLUSIONS: In this rat hepatocyte model of IL-1/benzenetriol-mediated injury, NO, derived from endogenous synthesis or an exogenous donor, is protective. Oxidative stress may have a role in the transcriptional control of NO synthesis.