[Changes in the activity of neutral and acidic isoforms of sphingomyelinase in hepatoma-22, regenerating and ischemic...

Activity of neutral and acidic sphingomyelinases (N- and A-SMases) were studied in regenerating liver after partial hepatectomy (during 48 hrs after operation), in ischemic liver during 15, 30 min and 1 and 2 hrs ischemia and during following reperfusion (from 5 min up to 2 hrs), in hepatoma- 22 after 15 days of transplantation and in liver of tumor bearing animals. It was shown that activity of N-SMase is increased in hepatoma-22 and in regenerating liver and it is decreased in ischemic liver. Following reperfusion of ischemic liver area activity of enzyme was found to have returned to baseline in dependence on time of ischemia and reperfusion. Activity of A-SMase is decreased in tumor, is not changed in regenerating liver and increased after long time of ischemia. It was supposed that N-SMase is involved in cell proliferation, but A-SMase is connected with cell damage.