Diazoxide Suppresses Hepatic Ischemia/Reperfusion Injury After Mouse Liver Transplantation by a BCL-2-Dependent Mechanism

Background: Ischemia-reperfusion injury (IRI) is responsible for primary liver dysfunction and failure after transplantation. The mitochondrial pathway appears to be involved in liver ischemia-reperfusion injury. Mitochondrial ATP-sensitive K (mitoKATP) channels play a central role in protecting the heart from injury in ischemic preconditioning. The selective mitoKATP channel agonist diazoxide potently reduced mitochondrial injury by preventing cytochrome c loss from the intermembrane space. Therefore, this study sought to determine whether diazoxide can attenuate ischemia-reperfusion injury induced by orthotopic liver transplantation (OLT) in mice. Furthermore, it was found that up-regulation of the Bcl-2 gene is a mechanism of diazoxide cytoprotection. Materials and Methods: Donors were treated with diazoxide, Bcl-2 siRNA, or diazoxide + Bcl-2 siRNA and vehicle 10 min or 24 h before liver harvesting. Liver grafts were then orthotopically transplanted into their corresponding recipients. Results: Liver injury, as judged by transaminase level and histologic examination, was significantly lower in the diazoxide group compared with vehicle controls. The percentage of apoptotic cells and the amount of cytochrome c in the cytosol 6 h after transplant were also markedly reduced in diazoxide-treated grafts compared with vehicle-treated controls. Diazoxide notably up-regulated expression of Bcl-2, while siRNA knockdown of Bcl-2 abolished the cytoprotective effects of diazoxide. Conclusions: Diazoxide attenuated graft injury after mouse liver transplantation. One mechanism of diazoxide protection involves the induction of Bcl-2, an anti-apoptotic protein. Diazoxide might be useful clinically in hepatic surgery and transplantation. [ABSTRACT FROM AUTHOR]