Effect of fatty acid saturation in membrane lipid bilayers on simple diffusion in the presence of ethanol at high concentrations

When multilamellar liposome trapping calcein, the fluorescent dye, was suspended in buffered ethanol containing the quencher, cobalt (II) ions, the increase in ethanol concentration in the range of 0-17.5% was accompanied with a striking decrease in fluorescence intensity, suggesting that permeability to the liposome membrane depended upon the ethanol concentration. In buffer containing 17.5% ethanol, as the percentage of phospholipid in which the 1- and 2-positions were occupied by saturated fatty acids increased in PC-PE liposome, there was a progressive decrease in velocity coefficient in quenching fluorescence, and the ratio of PC/PE appeared to have little effect on velocity coefficient. Intracellular nucleotide in cell suspension in 20% ethanol at 15 degrees C appeared to diffuse to the liquid phase by simple diffusion, and palmitic acid-enriched cells showed a lower permeability coefficient P', compared with linoleic acid-enriched cells, regardless of intracellular ergosterol content. The survival in linoleic acid-enriched cell was less than that of palmitic acid-enriched cells, suggesting that cell viability corresponded with P'.