Abstract
Partial removal of the adult rat liver--a procedure that stimulates liver regeneration--causes arterial levels of insulin and thyroxin to fall and glucagon levels to rise. These changes are correlated with the quantity of liver tissue excised and not solely with nonspecific operative manipulations or with blood glucose levels. During regeneration (about 24 hr postoperatively), hepatic plasma membranes become partially resistant to binding glucagon; this change is specific because it is not detected in laparotomized controls and insulin binding is not significantly altered. It remains to be proven whether any one or more of these specific endocrine changes are casually related to the initiation of hepatic proliferation.