Protein Synthesis in the Gastrointestinal Tract and Its Modification by Ethanol
This chapter reviews the effects of ethanol on the gastrointestinal tract, details the effects of ethanol on gastrointestinal protein synthesis, and attempts to provide possible mechanisms for the ethanol-induced inhibition of protein synthesis. Protein turnover is a dynamic process whereby tissue proteins are continuously being synthesized and broken down. In the steady-state situation, tissue protein content is maintained. Tissues such as the mouth, esophagus, and stomach are therefore exposed to the highest concentrations of ethanol. Ethanol is a small molecule and slightly polar, it is both water and fat soluble. Therefore, ethanol is easily absorbed and can traverse cell membranes by simple diffusion, without any expenditure of energy. The functions of the small intestine involve the digestion and absorption of various nutrients that pass from the stomach. There are various reliable methods for measuring tissue protein synthesis in vivo. Most methods for assessing the rate of protein synthesis involve the measurement of the incorporation of radiolabeled amino acids into protein.