Rogers Hollis, Zibari Gazi B, Roberts Jenifer, Turnage Richard, Lefer David J
Department of Surgery, Louisiana State University Health Sciences Center, Shreveport, 71130, USA.
Clin Transplant. 2004;18 Suppl 12:7-11. doi: 10.1111/j.1399-0012.2004.00210.
Liver ischaemia-reperfusion (I/R) occurs during resuscitation from haemorrhagic shock, hepatic transplantation and anatomic resection of the liver. This injury is associated with hepatocellular enzyme release and hepatocyte necrosis. The impact of chronic illnesses such as diabetes mellitus (DM) on hepatic I/R is unknown. This study determines the effect of DM on liver I/R using a murine model of type II DM in which the leptin receptor is defective. Preliminary studies suggest that animal models of DM have impaired endothelial nitric oxide (NO) release. Other studies suggest that NO attenuates hepatic I/R in phenotypically normal animals. We postulated that DM exacerbates hepatic I/R and that exogenous NO administration will attenuate hepatocellular injury.
Non-diabetic and diabetic (db/db) mice were anaesthetized and underwent laparotomy with the placement of a microvascular clip on the hepatic artery and portal vein supplying the medial and left lateral lobes of the liver rendering about 70% of the liver ischaemic. Hepatic ischaemia was maintained for 45 min after which time the clip was removed and the liver segments reperfused. The abdomen was closed and the animals maintained for 5 h of reperfusion. Hepatic injury was then assessed by measuring serum alanine and aspartate transaminases (ALT, AST) spectrophotometrically. Sections of liver reperfused for 24 h were stained with haematoxylin and eosin and the percentage of hepatocyte necrosis evaluated using morphometric techniques. Other animals undergoing hepatic I/R received the NO donor (DETA 100 micro g/kg, i.v. 5 min prior to reperfusion). Time-matched, sham-operated animals served as controls. The data are expressed as mean +/- SEM and analysed by ANOVA.
Serum AST and ALT levels were significantly higher in db/db animals vs. non-diabetics, even in the absence of hepatic I/R (P < 0.01). Serum AST and ALT levels in db/db mice undergoing hepatic I/R were nearly five times greater than that of non-diabetic animals (P < 0.01). Histologic examination of the livers of the diabetic animals undergoing I/R demonstrated significantly greater hepatocellular necrosis (zone III; 30-40%) when compared with non-diabetic animals sustaining the same injury (zone III; 3-10%). The NO donor DETA totally prevented the increase in serum ALT and AST release associated with I/R in both the diabetic and non-diabetic mice when compared with animals not receiving this agent (P < 0.01).
This is the first study suggesting that DM exacerbates hepatic I/R and that NO donors will prevent this hepatocellular injury in the diabetic. Sixteen million Americans have DM. Understanding the effect of this chronic illness on the inflammatory response to injury is essential to improving clinical outcomes in these medically compromised patients.
肝脏缺血再灌注（I/R）发生于失血性休克复苏、肝移植及肝脏解剖性切除过程中。这种损伤与肝细胞酶释放及肝细胞坏死相关。糖尿病（DM）等慢性疾病对肝脏I/R的影响尚不清楚。本研究利用瘦素受体缺陷的II型糖尿病小鼠模型，确定DM对肝脏I/R的影响。初步研究表明，DM动物模型的内皮一氧化氮（NO）释放受损。其他研究表明，NO可减轻表型正常动物的肝脏I/R。我们推测，DM会加剧肝脏I/R，而外源性给予NO可减轻肝细胞损伤。
将非糖尿病和糖尿病（db/db）小鼠麻醉后行剖腹术，在供应肝脏中叶和左外叶的肝动脉和门静脉上放置微血管夹，使约70%的肝脏缺血。肝脏缺血维持45分钟后移除夹子，肝段再灌注。关闭腹腔，动物维持再灌注5小时。然后通过分光光度法测量血清丙氨酸和天冬氨酸转氨酶（ALT、AST）来评估肝损伤。对再灌注24小时的肝脏切片进行苏木精和伊红染色，并用形态计量学技术评估肝细胞坏死百分比。其他接受肝脏I/R的动物在再灌注前5分钟静脉注射NO供体（DETA 100μg/kg）。时间匹配的假手术动物作为对照。数据以平均值±标准误表示，并通过方差分析进行分析。
即使在没有肝脏I/R的情况下，db/db动物的血清AST和ALT水平也显著高于非糖尿病动物（P<0.01）。接受肝脏I/R的db/db小鼠的血清AST和ALT水平几乎是非糖尿病动物的五倍（P<0.01）。对接受I/R的糖尿病动物肝脏的组织学检查显示，与遭受相同损伤的非糖尿病动物（III区；3-10%）相比，肝细胞坏死显著增加（III区；30-40%）。与未接受该药物的动物相比，NO供体DETA完全阻止了糖尿病和非糖尿病小鼠中与I/R相关的血清ALT和AST释放增加（P<0.01）。
这是第一项表明DM会加剧肝脏I/R且NO供体可预防糖尿病患者肝细胞损伤的研究。1600万美国人患有DM。了解这种慢性疾病对损伤炎症反应的影响对于改善这些医学上存在问题的患者的临床结局至关重要。
