A Research On Self-designed Hypothermic Solution's Effects On Liver Under Portal Vein Occlusion

Objectives:an animal model of portal vein inflow occlusion will be established by Bridging the superior mesenteric vein and the infrahepatic vena cava with blood vessel prosthesis so as to study the tolerance limit of portal vein occlusion. Then, based on this model, an observation of three groups safe duration limits (non-reperfusion, trans-portal vein perfusion with Ringers in vivo, and self-designed hypothermic solution) will be made to evaluate their effects on liver under portal vein occlusion. Finally, we prove that self-designed hypothermic solution through transportal vein is of good effect on the protection of the liver.Methods:Firstly, fourteen Bama swines are divided into group A in which the portal vein blood inflow is occluded for 120 minutes and group B in which the portal vein blood inflow is blocked for 150 minutes. The animal survival rate, the changes of liver function and histopathology are observed and analysized. After getting the tolerance limit of portal vein occlusion, Self-designed solution were perfused through the portalwein in the D group(n=7),or a similar volume and speed of Ringer's solution in control group(n=7). The 2 groups pigs'portal vein are all occlussed for 120 min.Blood and liver biopsies were sampled at 120 min ischemia, 120 min reperfusion and 1,3,5 days after operation assessed for transaminases, TNF-α, lighte microscopy and lectron microscopy.Results:1,All through the portal vein occlusion process, there is not any significant congestion, and the color of gut is normal. Therefore, the temporary porta-caval shunt is efficient.2,The animal survival rate of group A is significantly higher than that of group B (100% vs 57.1% , P < 0.05).3,For A and B groups, a rise of their ALT, AST, TBIL values can be observed, with the peak value appearing at 2 h after reperfusion. Then, all values decrease 3 days after reperfusion. And, there are more significant changes in the values of AST than that of ALT. The above changes in group A are higher than that of group B. 150 minutes after portal vein occlusion, there is great amount of hemorrhage in portal area in group B. Two hours after reflow phenomenon, we find further deteriorated lesions: its fat is degenerated. There is widely ballooning degeneration of hepatocyte, swelling endothelial cells, and congestion of sinus hepaticus. And in comparison with group B, liver tissues of group A suffer less damage under light microscope or electric microscope. Under the electric microscope, mitochondrion edema phenomenon and the expansion of endoplasmic reticulum of group B is more evident, and there are small nucleus(most concentrated nucleus), deposition of fibrous matrix, and other irreversible injury.5,The animal survival rate of group A, group C and group D are all 100%,without obvious difference.6,Liver founction comparison: for the value of ALT, there is significant differences between group A, C, C, based on the observation 2 hours after reperfusion, 1hour after the operation, and 3 hours after the operation(P<0.05). Group A is much higher than group D, group C is in between group A and D. For the value of AST 2 hours after reperfusion, the group A = 1229±275.1 IU/L, group C= 917±289.5 IU/L, group D=459.8±279.6 IU/L. Their values are quite different (P<0.05). Based on the observations 2 hours after reperfusion, and 1 hours after operation, we find the values of AST are no difference between group A and group C, the values of AST are quite different(group D, the self-designed hypothermic solution group, is lower than group C , the Ringer's solution group.) For the value of TBLL, based on the observations before the reperfusion and 3 days after the operation, we find that group A is quite different from group D because the self-designed hypothermic solution group is obviously lower than the group A.7,According to pathological scores and statistics analysis, 2 hours after reperfusion we find that group D(the self-designed solution group) has fewer inflammatory cell infiltration in portal vein areas in comparison with group A. Its hepatic sinusoid turns to be wider. There is no significant difference between the liver histopathology two hours after reperfusion and that before the occlusion (P>0.05). 5 hours after operation, pathological changes occurred, the liver functions of both group C and group D recover to the pre-occlusion level. The hepatic lobules are in their normal structure, without significant cellular edema or ballooning degeneration. There is no significant difference between the liver histopathology 5 hours after operation and that before the occlusion (P>0.05). However, for animals in group A, we can still see inflammatory cells and mild edemas in their livers. After operation, group A recover most slowly, and group D's rehabilitation process is better than that of group A and group C.8. The ultra-structures damages of group D (self-designed hypothermic solution group) is fewer than that of group A and group C. In group D, there were only mild mitochonodria and dilatation of endoplasmic reticulum. Their nuclear morphometry is almost normal.Conclusions:1. We have established a good animal model of portal vien occlusion with meso-caval bypass useing artificial blood vessel in Bama swines. The model can avoid mesenteric congestion ,so can reflect the degree and time cause change of damage during I/R of liver exactly while portal vein occlusion only.2. 120 minutes is the tolerance limit for the portal vein occlusion for Bama swine under conditions of meso-caval shunt.3. Self-designed solution can be perfused through portal vein in vivo safely. Self - designed solution can protect well the injury of worm I/R for portal vein occlusion only. It is better than Ringer'solution.