Levels of hepatic stimulator substance in liver regenerating process of partially hepatectomized rats pretreated with a single dose of carbon tetrachloride

Liver regeneration after injury with carbon tetrachloride (CCl4) followed b y partial hepatectomy is a complex model involving toxicological, inflammat ory, and necrotic processes. In the present study, the time-course of hepat ic regenerative process was investigated in relation to hepatic stimulator substance (HSS) activity, administration of a single dose of CCl4 and parti al (70%) hepatectomy in male rats. To evaluate liver injury events, the lev els of serum aspartic aminotransferase (AST), alanine aminotransferase (ALT ), and alkaline phosphatase (ALP) were measured. Hepatic DNA synthesis reac hed a maximum at 36 hr after hepatectomy in contrast to the reported 24-hr and 32-hr peaks observed in nontreated hepatectomized rats. On the other ha nd, HSS activity appeared to peak at 28, 40, and 44 hr after hepatectomy in CCl4-treated rats, and it was quite a lot lower at 24, 32, 36, 48, and 60 hr. The hypothesis that HSS promotes liver regeneration but it does not ini tiate it, as other factors have been found to do, is discussed.