Stimulation of chloride transport by fatty acids in corneal epithelium and relation to changes in membrane fluidity.
The effect of altering cell membrane lipids on ion transport across isolated corneas was studied. Corneas mounted in Ussing-type chambers showed a rapid increase in short-circuit current following treatment with a variety of unsaturated fatty acids of varying chain length and unsaturation. Measurements of membrane fluidity which utilize immunofluorescence labelling of membrane proteins showed corneal epithelial cell membranes to be significantly more  fluid following linoleic acid treatment. Uptake studies indicate rapid incorporation of [14C]linoleic acid into corneal cell membranes. Highly unsaturated fatty acids were found to have the greatest ability to stimulate chloride transport. Saturated fatty acids were tested and were found to have no effect on chloride transport at any concentration. It is proposed that unsaturated fatty acids activate chloride transport by increasing membrane lipid fluidity. The relationship of these parameters is discussed in terms of a mobile receptor model. We speculate that an increase in membrane lipid fluidity promotes lateral diffusion of membrane receptor proteins and enzymes, increasing protein-protein interactions within the membrane, ultimately resulting in the enhancement of cyclic AMP synthesis.
D000818:Animals; D001001:Anura; D001095:Arachidonic Acids / Q000494:pharmacology; D001692:Biological Transport; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D003315:Cornea / Q000187:drug effects / Q000378:metabolism*; D016861:Cyclooxygenase Inhibitors; D005227:Fatty Acids / Q000494:pharmacology*; D008041:Linoleic Acids / Q000378:metabolism; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000502:physiology; D011817:Rabbits; D011892:Rana catesbeiana
D001095:Arachidonic Acids; D002712:Chlorides; D016861:Cyclooxygenase Inhibitors; D005227:Fatty Acids; D008041:Linoleic Acids; D008563:Membrane Lipids