Journal of Lipid Research, Vol 27, 1044-1051, Copyright © 1986 by Lipid Research, Inc.
The role of circulating mevalonate in nephrotic hypercholesterolemia in the rat
TA Golper, KR Feingold, MH Fulford and MD Siperstein
The cause of the hypercholesterolemia that characterizes the nephrotic
syndrome has never been adequately explained. The present study examines
the possibility that enhanced availability of the cholesterol precursor,
mevalonic acid, to the liver in the nephrotic state may result in increased
hepatic cholesterogenesis. In normal animals, the kidneys are known to be
the major site of the metabolism of circulating mevalonate to both
cholesterol and CO2. Previous studies, using perfusion of isolated, intact
kidneys, have shown that the excretion and metabolism of mevalonate are
both impaired in nephrosis. The present investigation has demonstrated in
vivo that puromycin aminonucleoside nephrosis results in a 25% reduction in
the oxidation of mevalonate to CO2. In the same nephrotic animals,
cholesterogenesis from circulating mevalonate was significantly increased
in both liver and carcass. In addition, liver slices from nephrotic animals
incorporated increased amounts of [5-14C]mevalonate into cholesterol when
calculated per whole liver, but not per gram of liver. Oxidation of
mevalonic acid by kidney slices was significantly reduced, whether
expressed as per gram of tissue or per whole organ. HMG-CoA (3-hydroxy-
3-methylglutaryl) reductase activity in liver of nephrotic animals was
significantly increased. We conclude that, in the nephrotic state, impaired
mevalonate metabolism by the kidney may contribute to enhanced
cholesterogenesis by increasing delivery of mevalonate to liver and
carcass; in addition, nephrosis appears to provide an undefined stimulus
for HMG-CoA reductase activity in the liver, thereby providing an
additional enhancement of hepatic cholesterogenesis.