The NO/ET-1 system is involved in the protection of the hepatic ischemic preconditioning

Abstract

To study the relationship between the disturbance of nitric oxide/endothelin-1 (NO/ET-1) and the hepatic ischemia/reperfusion (I/R) injury as well as the regulation of the NO/ET-1 system by the hepatic ischemic preconditioning (IPC), the changes of the NO/ET-1 system and their relationship with the hepatic I/R injury were compared between the I/R group and the IPC+I/R group in a rat hepatic I/R model. 2 h after reperfusion, the liver tissues were examined for expressed inducible nitric oxide synthase (iNOS) mRNA by RT-PCR. In the acute phase of hepatic reperfusion, the ratio of NO/ET-1 was reduced, which was due to the significant reduction of NO₂⁻/NO₃⁻ (the metabolic product of NO) and significant elevation of ET-1 in the blood plasma. The content of ALT, AST, LDH and TNF-α in blood plasma, and level of MDA in liver tissue were increased but ATP in liver tissue was reduced, and the hepatic damage was deteriorated. The protection of the hepatic IPC was associated with the elevated ratio of NO/ET-1 caused by the elevation of NO₂⁻/NO₃⁻, and reduction of ET-1 as well. No iNOS mRNA was detected in the liver tissues. It was concluded that hepatic I/R injury was related to the disturbance of NO/ET-1. The protection of the hepatic IPC in the acute phase might be mediated by its regulation of NO/ET-1 system. The cNOS rather than the iNOS generated the NO in this scenario.

Keywords

liver / reperfusion injury / ischemic preconditioning / nitric oxide / endothelin-1

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