Journal of Lipid Research, Vol 19, 489-494, Copyright © 1978 by Lipid Research, Inc.
Rapid increase in hepatic HMG CoA reductase activity and in vivo cholesterol synthesis after Triton WR 1339 injection
S Goldfarb
Triton WR 1339, injected intravenously into rats, caused a 12% decrease in
hepatic cholesterol within 30 minutes and a 34% decrease after 2 hours. An
early and progressive increase in plasma cholesterol and triglycerides was
also confirmed. Although hepatic HMG Coa reductase activity was unchanged
after 30 minutes, it had increased seven-fold after 105 minutes. In vivo
cholesterol synthesis measured by determining incorporation of
intraperitoneally-injected 3H2O into cholesterol also showed an early
increase, suggesting that the enzyme was rate controlling for
cholesterogenesis under conditions of rapid stimulation. These findings
strongly suggest that Triton WR 1339 stimulates hepatic cholesterogenesis
by depleting hepatic cholesterol and trapping it in the blood compartment.
The rapidity with which the drug acts supports the hypothesis that
hepatocellular flux of cholesterol or its derivatized product could mediate
the diurnal and hormonally induced fluctuations of cholesterogenesis.