AJP - Gastrointestinal and Liver Physiology, Vol 249, Issue 6 679-G684, Copyright © 1985 by American Physiological Society
Cholesterol metabolism in regenerating liver of the rat
F. J. Field, S. N. Mathur and D. R. LaBrecque
The regenerating rat liver was used as a model to investigate the necessity
for new cholesterol synthesis prior to the onset of cell division. Plasma
cholesterol levels in partially hepatectomized rats were significantly
decreased 24 and 48 h after surgery compared with levels in sham-operated
animals. Hepatic cholesteryl ester content was also significantly increased
in livers from partially hepatectomized animals, but the hepatic content of
unesterified cholesterol was not affected. Hepatic triglyceride content was
significantly increased within 6 h after surgery in the regenerating liver.
The triglyceride levels reached a peak at 24 h, and by 72 h they had
decreased back to levels that were no different from control. In the
regenerating liver, microsomal 3-hydroxy-3-methylglutaryl CoA (HMG-CoA)
reductase activity was increased 12 h after surgery. The activity of this
enzyme remained significantly elevated throughout the 72-h period after
surgery. In contrast, 12 h after partial hepatectomy the rate of hepatic
cholesterol synthesis was significantly lower than that observed in livers
from sham-operated rats. An increase in the rate of cholesterol synthesis
was not observed until 48 h after partial hepatectomy, some 32 h after the
start of DNA synthesis. Microsomal acyl-CoA:cholesterol acyltransferase
activity was unchanged except for a 28% decrease at 72 h after partial
hepatectomy. The data suggest that new cholesterol synthesis is not a
requirement prior to the initiation of DNA synthesis in the regenerating
rat liver.(ABSTRACT TRUNCATED AT 250 WORDS)
