The ethanol-induced alterations in membrane structure, biogenesis, and turnover may contribute to the development of alcoholic tissue injury. Although membranes contain 40-60% lipids, the effects of ethanol consumption on the assembly of lipids into membranes has received little attention. Our hypothesis is that ethanol consumption alters membrane structure and function by 1) interfering with the formation, sorting, and subsequent intracellular translocation of specific pools of molecular species to their targeted domains within membranes; and 2) as a consequence, alters the activities of membrane proteins, e.g. ion channels. This hypothesis will be tested by a two pronged approach. To test the first part specific pools of phospholipids will be tagged according to their route of synthesis by treating cells with labeled precursors to the polar groups (choline, ethanolamine, serine, inositol). The effects of ethanol consumption will be determined by comparing the synthesis of the individual molecular species and their appearance on an isolated PM fraction isolated from cells of control and ethanol-fed rats. Although in recent years, the protein theory of alcohol and general anesthetic action has received strong support, it has been demonstrated that the activities of some membrane associated proteins and/or their responses to ethanol and n-alkanols are also modulated by the composition of the lipid bilayer. To test the second part of our hypothesis we will determine if changes in phospholipid composition influences the function of specific recombinant ion channels. Recombinant ion channels will be expressed in oocytes and the isolated channels will be reconstituted into planar lipid bilayers. We will examine the role of the polar and hydrophobic lipid environments on functions of channels incorporated into the bilayers. Since many physiological actions of ethanol and general anesthetics are thought to be mediated by their action on ion channels found in excitable tissues, we also plan to investigate whether the lipid composition also modulates their interactions with the channels. Impaired trafficking of phospholipids to the plasma membrane caused by ethanol consumption could significantly affect cells by causing disturbances in the lipid bilayer, metabolic lipid domains, membrane growth and maintenance, transporters, ion channels; and receptors for hormones and growth factors.
