Effect of low magnesium concentration and cholestane-3beta, 5alpha, 6beta-triol on levels of LDL receptor in cultured fibroblasts.

We investigated the level of low density lipoprotein receptors (LDLR) in fibroblasts upon treatment with low magnesium and/or cholestane-3beta, 5alpha, 6beta-triol (TriolC). After 72 h of incubation with low magnesium at a level of 188 micromol or lower, the LDLR levels, determined with immunoblotting analysis, were significantly reduced in the cultured cells. TriolC at a level of 1 microg/ml or higher also decreased LDLR level. However, no further decrease of LDLR level was detected in the cells treated with low magnesium plus TriolC at a level of 0.1 microg/ml, compared with the LDLR level from the cells treated with low magnesium only. Our results showed that both low magnesium concentration and TriolC reduced the LDLR level, but the reducing effect was not accentuated when both were present in the culture medium.