PT  - JOURNAL ARTICLE
AU  - J. H. CHIN
AU  - D. B. GOLDSTEIN
TI  - Membrane-Disordering Action of Ethanol
DP  - 1981 May 01
TA  - Molecular Pharmacology
PG  - 425--431
VI  - 19
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/19/3/425.short
4100  - http://molpharm.aspetjournals.org/content/19/3/425.full
SO  - Mol Pharmacol1981 May 01; 19
AB  - With the use of 5-doxylstearic acid as the spin probe, we previously found that low concentrations of ethanol in vitro reduced the order of mouse biomembranes and that similar membranes isolated from mice after 8 days of ethanol treatment had an elevated cholesterol content and were resistant to the in vitro disordering effect of ethanol. To localize the effects of ethanol, compare ethanol effects with temperature effects, and explore the relationship between cholesterol and ethanol, we have now measured order parameters of mouse synaptosomal plasma membranes and of multilayer vesicles composed of egg phosphatidylcholine and cholesterol, spin-labeled with 5-doxyl-, 12-doxyl-, or 16-doxylstearic acid. The bilayer was more ordered at the region monitored by the 5-doxyl than the 12- or 16-doxyl label, and was made less ordered by warming or by the addition of ethanol (0.35 M). The disordering effect of ethanol (decrease in order parameter) was greater at high temperatures than at low temperatures and was progressively reduced by the addition of cholesterol. In brain membranes, ethanol had a greater effect with 12- and 16-doxylstearic acid than with the 5-doxyl label. In phospholipid model membranes, incorporation of cholesterol increased the order parameter of 12-doxylstearic acid more than that of the 5-doxyl label. In general, the effect of ethanol was greater at high temperatures, low cholesterol concentrations, or in the interior of the membrane between the surface and the core. Ethanol may thus act most strongly in relatively disordered domains of neuronal membranes. ACKNOWLEDGMENTS We wish to thank Ken Dill, James Trudell, and Robbe Lyon for helpful discussions.