Actin-like contractile protein in carbon tetrachloride-induced cirrhosis in the rat.

Cryostat sections of livers from rats treated with carbon tetrachloride (CCl4) for 12 weeks were examined by indirect immunofluorescence for reactivity with human serum containing smooth muscle antibody (SMA). Increased binding of SMA serum to hepatocytes was observed as early as the first week of CCl4 treatment and remained enhanced during the 12 weeks of study. No difference in staining intensity was observed between pre-cirrhotic liver parenchymal cells and hepatocytes in regenerative nodules of frankly cirrhotic livers. In addition, granulation tissue fibroblasts in cirrhotic livers showed strong reactivity with SMA serum. The specificity of the staining reaction for actin was established by its prevention on neutralization absorptions of the serum with homogenates of smooth muscle or extracts containing actin derived from smooth muscle. Circulating SMA was not demonstrated in the serum of rats at any phase of the study. The observations show that there is an increased expression of actin-like protein in regenerating hepatocytes and granulation tissue fibroblasts in cirrhotic livers.