Comparative effects of ethanol and other depressant drugs on membrane order in rat synaptosomes using ESR spectroscopy.
The effects of ethanol, t-butanol and pentobarbitone on the membrane order of rat synaptosomal membranes have been compared using 3 spin-label probes, 5-doxyl-stearic acid which reports from a lipid site near the membrane surface, 16-doxyl-stearic acid which reports from a deeper lipid site, and maleimide-TEMPO which covalently binds to membrane protein. The sensitivity of the membrane proteins to a fluidizing effect of ethanol was increased by lowering the concentration of protein-binding probe. Significant decreases in membrane order were observed at anaesthetic concentrations of ethanol and t-butanol with all three probes; pentobarbitone produced a similar effect but only at very high concentrations. Pentobarbitone caused a marked change in high-field peak shape of the 16-doxyl-stearic acid spectra at anaesthetic concentrations; this effect was seen slightly with t-butanol and trichlorethanol but not with ethanol. These studies indicate that the membrane sites of action of ethanol and pentobarbitone as shown by ESR probes are different.
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D000440:Butanols / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D000431:Ethanol / Q000494:pharmacology*; D008560:Membrane Fluidity / Q000187:drug effects*; D008563:Membrane Lipids / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D010424:Pentobarbital / Q000494:pharmacology*; D051381:Rats; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism; D020002:tert-Butyl Alcohol
D000440:Butanols; D008563:Membrane Lipids; D008565:Membrane Proteins; D000431:Ethanol; D010424:Pentobarbital; D020002:tert-Butyl Alcohol