Influence of Cholesterol Oxidation Derivatives on Membrane Bound Enzymes in Cultured Aortic Smooth Muscle Cells 1

Abstract

Abstract

Cholestane-3β,5α,6β-triol and 25-hydroxycholesterol are two of the most cytotoxic and also relatively abundant of the autoxidation derivatives of cholesterol. Cultured aortic smooth muscle cells which were incubated with 10 μg/ml of either sterol for 24 to 48 hr showed a marked decrease of 5′-nucleotidase activity in isolated crude membranes. It was further demonstrated that 5′-nucleotidase activity was also markedly decreased in plasma membrane-enriched fractions when cells were incubated with cholestane-3β,5α,6β-triol. Na⁺, K⁺-ATPase activity in crude membranes showed a significant decrease (32%) only in cells incubated with cholestane-3β,5α,6β-triol for 48 hr. There was no effect on Na⁺, K⁺-ATPase activity in cells incubated for 24 hr with either sterol.