Yin D P, Sankary H N, Chong A S, Ma L L, Shen J, Foster P, Williams J W
Department of General Surgery, Rush-Presbyterian-St. Lukes Medical Center, Chicago, Illinois 60612, USA.
Transplantation. 1998 Jul 27;66(2):152-7. doi: 10.1097/00007890-199807270-00002.
Ischemic-preconditioning is a process whereby a brief ischemic episode confers a state of protection against subsequent long-term ischemia-reperfusion injury. Ischemic preconditioning has been studied in heart and liver ischemia-reperfusion injury; however, few studies have been performed in the model of preservation-reperfusion injury in liver transplantation. The current study was designed to evaluate the ability of ischemic preconditioning to protect liver grafts from long-term preservation-reperfusion injury.
Male Sprague Dawley rats were used as donors and recipients of orthotopic liver transplantation. Ischemic preconditioning was done by interruption of the portal vein and hepatic artery for 5, 10, and 20 min (5-10, 10-10, and 20-10 groups). Reflow was initiated by removal of the clamp for another 10 min in all groups. The liver was removed and placed in a bath with Euro-Collins solution for different preservation times. Tolerance of the transplanted liver to cold ischemia was determined by survival time and liver function tests. Rat tumor necrosis factor was analyzed by a bioassay. Nomega-Nitro-L-arginine methyl ester, L-arginine, or adenosine was administered to block or stimulate the synthesis of nitric oxide (NO) in the rats that received long-term-preserved liver grafts.
Twenty percent of syngeneic rats (n=10) that received a liver graft with a 16-hr cold ischemia time in Euro-Collins solution survived for more than 1 day and 10% survived for more than 5 days. In contrast, 87.5% of rats (n=8) that received a liver graft with ischemic preconditioning (10-10 group) and 16 hr of cold ischemia survived for more than 1 day and 75% for more than 5 days. Recipients of liver grafts with ischemic preconditioning had significantly reduced levels of serum aspartate transaminase and tumor necrosis factor-alpha, as well as increased bile flow, compared with recipients of liver grafts without ischemic preconditioning. Blockage of the NO pathway using Nomega-nitro-L-arginine methyl ester, a stereospecific competitive inhibitor of NO formation, attenuated the protective effect of ischemic preconditioning. Administration of one of two precursors of NO synthesis, L-arginine or adenosine, prolonged the survival of rats that received 16-hr-preserved liver grafts. In addition, L-arginine synergized with short-term ischemic pre conditioning (5-10 group) to increase the survival of rats that received a liver graft with a 16-hr cold ischemia time, and the survival rate was 83% after 5 days. Finally, prolonged ischemic preconditioning (> or = 20 min; 20-10 group) resulted in liver damage and loss of function.
The current results show that ischemic preconditioning protects the liver graft from subsequent long-term cold preservation-reperfusion injury in a rat liver transplantation model. The protective role of ischemic preconditioning may be mediated by the endogenous production of NO.
缺血预处理是一种过程，即短暂的缺血发作可赋予针对随后长期缺血再灌注损伤的保护状态。缺血预处理已在心脏和肝脏缺血再灌注损伤中得到研究；然而，在肝移植保存再灌注损伤模型中进行的研究较少。当前研究旨在评估缺血预处理保护肝移植免受长期保存再灌注损伤的能力。
雄性Sprague Dawley大鼠用作原位肝移植的供体和受体。通过阻断门静脉和肝动脉5、10和20分钟进行缺血预处理（5 - 10、10 - 10和20 - 10组）。所有组中通过移除夹子再灌注10分钟。取出肝脏并置于含有Euro - Collins溶液的浴中不同保存时间。通过存活时间和肝功能测试确定移植肝对冷缺血的耐受性。通过生物测定法分析大鼠肿瘤坏死因子。对接受长期保存肝移植的大鼠给予Nω-硝基-L-精氨酸甲酯、L-精氨酸或腺苷以阻断或刺激一氧化氮（NO）的合成。
在Euro - Collins溶液中接受冷缺血时间为16小时的肝移植的同基因大鼠（n = 10）中，20%存活超过1天，10%存活超过5天。相比之下，接受缺血预处理（10 - 10组）和16小时冷缺血的肝移植的大鼠中，87.5%（n = 8）存活超过1天，75%存活超过5天。与未进行缺血预处理的肝移植受体相比，进行缺血预处理的肝移植受体的血清天冬氨酸转氨酶和肿瘤坏死因子-α水平显著降低，胆汁流量增加。使用Nω-硝基-L-精氨酸甲酯（一种NO形成的立体特异性竞争性抑制剂）阻断NO途径减弱了缺血预处理的保护作用。给予两种NO合成前体之一L-精氨酸或腺苷可延长接受16小时保存肝移植的大鼠的存活时间。此外，L-精氨酸与短期缺血预处理（5 - 10组）协同作用可增加接受冷缺血时间为16小时的肝移植的大鼠的存活时间，5天后存活率为83%。最后，延长的缺血预处理（≥20分钟；20 - 10组）导致肝损伤和功能丧失。
当前结果表明，在大鼠肝移植模型中，缺血预处理可保护肝移植免受随后的长期冷保存再灌注损伤。缺血预处理 的保护作用可能由内源性NO产生介导。
