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Ascorbic acid regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and cholesterol synthesis in guinea pig liver.

Authors
Type
Published Article
Journal
Biochimica et Biophysica Acta
0006-3002
Publisher
Elsevier
Publication Date
Volume
834
Issue
1
Pages
134–138
Identifiers
PMID: 4038887
Source
Medline
License
Unknown

Abstract

Guinea pigs fed a normal diet show the expected diurnal variation in 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. Vitamin C deficiency, however, suppresses the diurnal peak activity of reductase, due to a decrease in active (unphosphorylated) enzyme. Inhibition of reductase is paralleled by both a fall in hepatic cholesterol synthesis and a rise in serum cholesterol. Incubation of normal guinea pig hepatic microsomes with physiologic and supraphysiologic concentrations of sodium ascorbate also leads to a concentration-dependent inhibition of reductase activity. Thus, dietary extremes of vitamin C may exert similar effects on reductase activity and cholesterolgenesis. Moreover, the changes in enzyme activity induced by ascorbic acid appear to be due in part to a direct effect of the vitamin on the microsomally bound enzyme.

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