Effect of subtotal pancreatectomy on the rate of liver regeneration: the role of hepatic stimulator substance.

The endogenous signals controlling liver regeneration are becoming rapidly defined. One of the key findings during liver regeneration following partial hepatectomy is the appearance of peripheral blood factors that stimulate DNA synthesis in the parenchymal cells. Hepatopoietin A, or hepatocyte growth factor, has been described as a complete mitogen for hepatocytes, one of its major tissue sources being the pancreas. The changes in the rate of DNA synthesis (incorporation of [3H] thymidine into DNA) in both subtotally pancreatectomized-partially hepatectomized (Group A) and partially hepatectomized (Group B) male rats were determined at different postoperation times. DNA synthesis in Group A was increased progressively, reaching a maximum at 40 hr after operation in contrast to the 24- and 32-hr peaks obtained in nonpancreatectomized rats (Group B). However, liver regeneration in Group A was significantly lower than in Group B. To evaluate the effects of hepatic stimulator substance (HSS) on liver regeneration, the time course of HSS biological activity during the liver regeneration process was determined in the livers of Group A rats. A concurrent change of HSS activity and rate of liver regeneration was observed. These results support the hypothesis that HSS biological activity may be delayed but not suppressed by subtotal pancreatectomy.