A useful framework is proposed for unifying the synthesis of
plasma proteins and their degradation by, or release from, liver cells of intact and partially hepatectomized rats, in which synthesis and release of acute-phase
plasma proteins occur in synchrony with the internalization and catabolism of plasma and extracellular
proteins. The catabolism of
proteins and other hepato-intracellular
glycoproteins during
sepsis or
trauma is essential to provide constituent
amino acids and
carbohydrates for the synthesis of acute-phase
plasma proteins. Increases in the plasma levels of
acute-phase response proteins in
sham-operated rats reached a maximum between 1 and 2 d after mock surgery, and had returned virtually to control levels within 6 d. By contrast,
acute-phase proteins in the plasma of partially hepatectomized rats were decreased by 10-20% of their initial values after 24 h. A maximum
acute-phase response on d 7 after the operation was characterized by an increase of 181, 445, and 19% for alpha-1-acid
glycoprotein,
hepatoglobin, and
hemopexin, whereas other
acute-phase proteins remained below control levels, for example, by 11, 25, and 38% for
albumin,
transferrin, and
prealbumin, respectively. This delayed response suggests that the nascent liver cells had inherited the capacity of the parent cells to respond to inflammatory signal and had synthesized acute-phase
plasma proteins. Accordingly, a time frame for the application of toxin to nascent hepatocytes is suggested. An increased activity (300 +/- 50%) for both bound and free
neuraminidase in remnant liver tissue 19 h post partial
hepatectomy suggested that hepatic regenerating factor(s) were produced in liver tissue via the hepatic bound and/or free
neuraminidase-mediated desialylation of humoral substrates. By contrast, circulating levels of lysosomal
enzymes alpha-fucosidase and beta-N-acetyl-D-
glucosaminidase were increased marginally after 24 h but had returned nearly to control levels after 7 d, suggesting that lysosomal
acid hydrolases do not play a major role in regenerative
DNA synthesis, mitosis, or in the synthesis of acute-phase
plasma proteins.