| Cold ischemia reperfusion injury in liver transplantation surgery is an important pathophysiological process, which affects the short-term and long-term survival rate of transplanted liver. Thus, taking measures to alleviate cold ischemia reperfusion injury on liver function make great sense in the liver transplantation. Most of anhepatic phase portal vein is interrupted during the operation of liver transplantation. It aggravates congestion of bowels, change of whole-body hemodynamics, dysfunction of intestinal mucosa barrier for ischemia and hypoxia and subsequently cause unbalance of inner circumstance which producing endotoxemia arising from the shift of endotoxin. When anhepatic phase portal vein is opening, congestive portal vein blood reflow to liver. It may activate the endotoxin signal pathways, produce a mount of inflammatory molecules as TNF- α , IL-6 leading to damage the donor liver. Studies demonstrate that the prolonged anhepatic phase increase death rate of rats that received orthotopic liver transplantation. The main reason may be a serial of pathophysiological changes in recipient rat caused by intestines congestion following the interruption of portal vein. Employing portocaval shunt method may reduce intestines congestion of animals, maintain viscus approximately physiological status, then endure longer anhepatic phase. The mechanisms of reperfusion injury might be different between single liver ischemia without portal vein congestion and that of portal vein congestion.A model of cold ischemia reperfusion injury of rat liver with portal-cervical bypass established in this experiment to compare different effect on rats function between the group of portal-cervical bypass and that of interruption of portal vein, which provides a reference for clinical operation manner to reduce cold ischemia reperfusion injury in liver transplantation.We inserted catheters manufactured in-house into external jugular vein and portal vein to make portal-cervical bypass, and into infrahepatic vena cava to make blood flow in infrahepatic vena cava reflow to heart via catheters.The low temperature preserved liverwas persistingly lavaged with 0~4°C Ringer's solution through portal vein, reperfusion preserved solution flowed out inner-set catheters via infrahepatic vena cava. After 150 minutes of reperfusion, the blood supply was resumed and the incision in the abdomen was suture off. Based on this animal model, the longest tolerance time was determined in anhepatic phase rat with interruption of portal vein. During the operation, portal vein was interrupted for different time from 35 min gradually decreased to 30 min and 25 min in different groups. Time that wherein all rats in groups were alive was designated as the longest tolerance time by observing these animals in one week. The survival rates in one week were 30% in 35 minutes' interruption of portal vein group, 70% in 30 minutes', 100% in 25 minutes' respectively. Also, the same survival rate in one week was 100% in complete portal vein bypass group. So, the longest tolerance time in anhepatic phase rats with interruption of portal vein might be 25 minutes.Furthermore, it was compared between anhepatic phase portal vein bypass and 25 min interruption of portal vein groups. Several indexes as liver morphology, physiological function, energy metabolism and cell apoptosis were analysed to determine whether the temporary portal vein bypass would play protective role in the cold ischemia reperfusion injury in rats liver. Experimental animals were divided into normal, interrupted and bypass three groups to observe the congestion degree of gastrointestines, spleen and recovery status. Rats were sacrificed in 11k 6h> 24h> 3d and 7d respectively after operation to examine liver function, pathological changes, ATP concentration, RCR (respiratory control ratio) of mitochondria, P/O (oxidative phosphorylation ratio), apoptosis of hepatic cells. Rats without obvious congestion of vein system could stand up in two hours after operation and liver color recover soon with renew blood supply in bypass group. Whereas, that with marked congestion of gastrointestines and spleen had poor spirit, longer recovery in portal vein interrupted group. The general status of the former was farther better that the later both in operation and post-operation. The mean values of serum level of ALT, AST reached the peak after one-hour operation in two groups of bypass and portal vein interrupted and came to decline gradually. However, it return to normal level in three days for the bypassed rats, it recovered in one week for the other. In addition, the ALT, AST level in the interrupted animals was significantly more than that of in the bypass one in the time-point of lh, 6h, 24h, 3d (p<0.05). Hepatic cellswith almost normal hepatic lobule structure appeared partial denaturalization and necrosis and inflammatory infiltration after lh, 6h operation in the bypass group. These pathological changes alleviate and recover after 24h and three days respectively. In contrast, hepatic cells with partially destroyed hepatic lobule structure appeared extensive denaturalization and necrosis after the same time of operation in the interrupted group. These more severe pathological changes alleviate and recover after 24h, 3d, and 7d respectively. The high ATP concentration, RCR and P/O at each corresponding time-point, and shorter recovery time in bypass group than that in interrupted group was found in mis experiment The amount of apoptotic hepatic cells showed a high level after 24h reperfusion in two groups, then gradually decline. The less apoptotic cells were determined in the bypass group than that of in the interrupted group in the same time-point After 7d reperfusion, there was not significant difference of apoptosis between these two groups.The current results show that the established animal model of cold ischemia reperfusion injury in rat liver with portal-cervical bypass is a simple, easy operated manner with shorter time of performance or intubatton, and good reproducibility, which may reduce the difficulty of blood vessel inosculation and simulate the whole process of liver transplantation. Twenty-five minutes may be the longest tolerance time in anhepatic phase rat with interruption of portal vein. Employing portocaval shunt method may reduce the congestion of gastrointestines and spleen, promote recovery of structure and function of rat liver after operation, improve energy metabolism and inhibit cell apoptosis after receiving cold ischemia reperfusion.
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