The significance of serum mitochondrial aspartate aminotransferase activity in obstructive jaundice: experimental and clinical studies.

The serum level of mitochondrial aspartate aminotransferase was determined in experimental and clinical obstructive jaundice, using an immunoabsorbance method which allowed the differential determination of cytosolic and mitochondrial isozymes in the serum. In experimental obstructive jaundice using dogs, the serum mitochondrial aspartate aminotransferase value rapidly decreased to normal after biliary decompression following a period of biliary obstruction of within 3 weeks. On the other hand, when the period of jaundice was prolonged for 5 weeks, the activity of the enzyme after biliary drainage still continued to show high values, being 14.2 +/- 1.8 Karmen units at 4 weeks following biliary decompression. Determination of aspartate aminotransferase activity in tissue from such organs as the liver, heart, kidney, skeletal muscle and brain, as well as serum samples withdrawn from local veins, confirmed that high serum values of the enzyme in experimental obstructive jaundice were mostly attributable to hepatic impairment induced by biliary obstruction not by secondarily damaged tissues of other organs. Mitochondrial aspartate aminotransferase proved to be a more useful marker than other routine tests in icteric dogs. In 13 clinical patients with obstructive jaundice, decreasing rates of serum mitochondrial aspartate aminotransferase on the 7th and 14th postoperative days could be applied to evaluate the viability of the icteric liver. The decreasing rates were more advantageous than the preoperative activity itself in predicting the postoperative function of the liver. Thus, mitochondrial aspartate aminotransferase appears to serve as a useful marker for assessing the liver function in obstructive jaundice.