Q. Zhou et Fa. Kummerow, ALTERATIONS OF CA-CONTENT IN CULTURED HUMAN ARTERIAL SMOOTH-MUSCLE CELLS TREATED WITH 26-HYDROXYCHOLESTEROL(+ UPTAKE AND LIPID), Artery, 21(4), 1994, pp. 182-192
The effects of 26-hydroxycholesterol on Ca-45(++) uptake, [C-14]choles
terol uptake, [C-14] acetate incorporation and the concentrations of 2
6-hydroxycholestero1 and cholesterol in the plasma membrane were studi
ed in cultured human smooth muscle cells isolated from umbilical arter
ies. The results showed that: (1) 26-hydroxycholesterol enhanced marke
dly Ca-45(++) uptake and the enhancement was not diminished by nifedip
ine; (2) 26-hydroxycholesterol decreased cholesterol content in plasma
membrane by inhibiting cholesterol uptake and synthesis, and [C-14]ch
olesterol uptake was not LDL-receptor dependent; (3) 26-hydroxycholest
erol induced a shift of [C-14] acetate from cholesterol into phospholi
pid synthesis, but the radioactive incorporation into triglyceride and
cholesterol ester was inhibited by 26-hydroxycholesterol; and (4) 26-
hydroxycholesterol inserted itself into the plasma membrane. We sugges
ted that 26-hydroxycholesterol changes the composition of membrane lip
ids with a consequential alteration of membrane permeability to Ca++.