Introduction

Abstract

There are three chapters in the gastrointestinal section of the book. The first, by Barry Hirst, considers the crucial, but often overlooked, barrier property of the upper gastrointestinal epithelium to acid and how this can be compromised by exposure of the epithelium to alcohols, aspirin and bile salts. After briefly reviewing studies conducted with the native epithelium, Dr Hirst considers potential model systems, in particular isolated membrane vesicles and cultured epithelial cells. The effects of alcohols and bile salts on the proton permeability and fluidity of apical membranes are described as is the resistance of epithelial cell cultures to acid. Both systems are judged to have provided important insights into the nature of the epithelial barrier to acid.