Alterations of Ca++ uptake and lipid content in cultured human arterial smooth muscle cells treated with 26-hydroxycholesterol.
The effects of 26-hydroxycholesterol on 45Ca++ uptake, [14C]cholesterol uptake, [14C] acetate incorporation and the concentrations of 26-hydroxycholesterol and cholesterol in the plasma membrane were studied in cultured human smooth muscle cells isolated from umbilical arteries. The results showed that: (1) 26-hydroxycholesterol enhanced markedly 45Ca++ uptake and the enhancement was not diminished by nifedipine; (2) 26-hydroxycholesterol decreased cholesterol content in plasma membrane by inhibiting cholesterol uptake and synthesis, and [14C]cholesterol uptake was not LDL-receptor dependent; (3) 26-hydroxycholesterol induced a shift of [14C] acetate from cholesterol into phospholipid 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 suggested that 26-hydroxycholesterol changes the composition of membrane lipids with a consequential alteration of membrane permeability to Ca++.
Zhou
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Burnsides Research Laboratory, University of Illinois, Urbana 61801, USA.
Kummerow
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FA
D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D002788:Cholesterol Esters / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D006801:Humans; D006888:Hydroxycholesterols / Q000378:metabolism / Q000494:pharmacology*; D050356:Lipid Metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D011973:Receptors, LDL / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism; D014469:Umbilical Arteries
D002250:Carbon Radioisotopes; D002788:Cholesterol Esters; D005230:Fatty Acids, Nonesterified; D006888:Hydroxycholesterols; D010743:Phospholipids; D011973:Receptors, LDL; D014280:Triglycerides; C007042:cholest-5-ene-3 beta,26-diol; D002784:Cholesterol; D002118:Calcium