OLEIC-ACID AND LINOLEIC-ACID ARE THE MAJOR DETERMINANTS OF CHANGES INKERATINOCYTE PLASMA-MEMBRANE VISCOSITY

Keratinocytes were grown in medium with no essential fatty acids as we ll as in media with specially selected fatty acid augmentations, Gas c hromatographic determinations of 21 fatty acids in the phospholipids w ere correlated with plasma membrane viscosity obtained by electron par amagnetic resonance studies (n = 24). Using standard procedures from m ultivariate analysis, we derived an expression that modeled the viscos ity data as a function of four key fatty acid levels: eta = 69.4 + 0.4 5 [16:1] + 0.97 [18:1] - 0.71 [18:2] - 0.28 [20:3] where the fatty aci ds are given in mole percent of total lipids and are identified as two number sequences: number of carbons followed by number of double bond s. No other fatty acid made a significant contribution to the regressi on equation. The range of viscosity was very large, varying from 60 to 120 cP over the sample population. The results are interpreted to ind icate that polyunsaturated fatty acids are replaced with monounsaturat ed fatty acids by the keratinocytes and that dihomogamma-linolenic aci d (20:3, n-6) plays an important role in membrane viscosity when essen tial fatty acids are available in the growth medium of these adult hum an cultured keratinocytes.