IN-SITU ANALYSIS OF ISCHAEMIA REPERFUSION INJURY IN RAT-LIVER STUDIEDIN 3 DIFFERENT MODELS/

Animal models of liver ischaemia and reperfusion are frequently used t o study the consequences on liver cells of transient oxygen deprivatio n. In 3 different rat models we studied ischaemia/reperfusion effects on liver cell membrane integrity, cytoplasmic enzyme proteins and enzy me activities by in situ histochemical techniques. In vivo ischaemia, as well as no-flow hypoxia, or N-2-induced hypoxia in isolated perfuse d livers, reduced the activity of 5'-nucleotidase, a sensitive marker for plasma membrane damage in hepatocytes. As little as 2 minutes of r eoxygenation in each model resulted in leakage of soluble enzymes from parenchymal and non-parenchymal liver cells, as shown by decreased pr otein level and activity of cytoplasmic enzymes. Whereas a multifocal decrease was observed after in vivo reperfusion, a decrease was found in all periportal and midzonal cells after blood-free reoxygenation. A s judged by alkaline phosphatase activity and immunohistochemistry, an influx of inflammatory cells was not found in the in vivo model. Our findings indicate that reoxygenation itself, rather than restoration o f flow, accounts for the loss of soluble enzymes from liver cells afte r a period of hypoxia. In situ detection of enzyme protein and activit y proved useful for the examination of very early ischaemia/reperfusio n effects on rat liver cells.