Oleic acid and linoleic acid are the major determinants of changes in keratinocyte plasma membrane viscosity

Keratinocytes were grown in medium with no essential fatty acids as well as in media with specially selected fatty acid augmentations, Gas chromatographic determinations of 21 fatty acids in the phospholipids were correlated with plasma membrane viscosity obtained by electron paramagnetic resonance studies (n = 24). Using standard procedures from multivariate analysis, we derived an expression that modeled the viscosity data as a function of four key fatty acid levels: eta = 69.4 + 0.45 [16:1] + 0.97 [18:1] - 0.71 [18:2] - 0.28 [20:3] where the fatty acids are given in mole percent of total lipids and are identified as two number sequences: number of carbons followed by number of double bonds. No other fatty acid made a significant contribution to the regression equation. The range of viscosity was very large, varying from 60 to 120 cP over the sample population. The results are interpreted to indicate that polyunsaturated fatty acids are replaced with monounsaturated fatty acids by the keratinocytes and that dihomogamma-linolenic acid (20:3, n-6) plays an important role in membrane viscosity when essential fatty acids are available in the growth medium of these adult human cultured keratinocytes.