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Aim: To study the effects of hypoxia, hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 (MMP-2) in hepatic stellate cells (HSC)., Methods: The expressions of MMP-2, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and membrane type matrix metalloproteinase-1 (MT1-MMP) in cultured rat HSC were detected by immunocytochemistry (ICC) and in situ hybridization (ISH). The contents of MMP-2 and TIMP-2 in culture supernatant were detected with ELISA and the activity of MMP-2 in supernatant was revealed by zymography., Results: In the situation of hypoxia for 12h, the expression of MMP-2 protein was enhanced (hypoxia group positive indexes: 5.7 +/- 2.0, n=10; control: 3.2 +/- 1.0, n = 7; P<0.05), while TIMP-2 protein was decreased in HSC (hypoxia group positive indexes: 2.5 +/- 0.7, n = 10; control: 3.6 +/- 1.0, n = 7; P < 0.05), and the activity (total A) of MMP-2 in supernatant declined obviously (hypoxia group: 7.334 +/- 1.922, n = 9; control: 17.277 +/- 7.424, n = 11; P < 0.01). Compared the varied duration of hypoxia, the changes of expressions including mRNA and protein level as well as activity of MMP-2 were most notable in 6h group. The highest value(A(hypoxia)-A(control)) of the protein and the most intense signal of mRNA were in the period of hypoxia for 6h, along with the lowest activity of MMP-2. In the situation of hyperoxia for 12h, the contents (A(450)) of MMP-2 and TIMP-2 in supernatant were both higher than those in the control, especially the TIMP-2 (hyperoxia group: 0.0499 +/- 0.0144, n = 16; control: 0.0219 +/- 0.0098, n = 14; P < 0.01), and so was the activity of MMP-2 (hyperoxia group: 5.252 +/- 0.771, n = 14; control: 4.304 +/- 1.083, n = 12; P < 0.05), and the expression of MT1-MMP was increased., Conclusion: HSC is sensitive to the oxygen, hypoxia enhances the expression of MMP-2 and the effect is more marked at the early stage; hyperoxia mainly raises the activity of MMP-2.

Background: Hepatic ischemia-reperfusion (I/R) is accompanied by liver weight gain and ascites formation. This could be caused by an increase in sinusoidal pressure, a determinant of hepatic transvascular fluid movement. We determined the role of sinusoidal pressure, assessed by triple vascular occlusion pressure (P(to)), in the I/R injury in isolated rat livers perfused with leukocyte-free diluted blood bivascularly via the portal vein and hepatic artery., Materials and Methods: Ischemia was induced at room temperature by occlusion of either the inflow lines of the hepatic artery and portal vein (the open outflow group, n = 10) or both the inflow and the outflow (hepatic venous) lines (the closed outflow group, n = 10) for 1 h, followed by 1-h reperfusion in a recirculating manner., Results: Liver weight in both groups increased biphasically after reperfusion; the initial peak occurred at 3 min and the second peak at 60 min. Immediately after reperfusion, P(to) peaked, followed by a gradual decline. The initial weight increase in groups combined was significantly and positively correlated with an increase in P(to) (r = 0.716, P = 0.0002), but the second peak was independent of P(to). Liver injury, assessed by perfusate levels of hepatic enzymes and reduced bile flow rate, was observed at 60 min after reperfusion in both groups., Conclusions: These findings suggest that increased sinusoidal pressure contributes to only the early liver weight gain after reperfusion in isolated perfused rat livers. The late weight gain may be presumably due to liver injury., (Copyright 2000 Academic Press.)