Introduction
暂无分享,去创建一个
The lumen of the gastrointestinal tract is exposed to a variety of ingested compounds and mucosal secretory products. Proteins, fats and carbohydrates are digested and the products of digestion and water arc absorbed. Damage to the gastrointestinal mucosa as a result of continuous exposure to the luminal contents is counteracted and normally balanced by protective mechanisms such as the neutralization of gastric acid and the dilution of irritating contents in the intestine by secretion. Further important mechanisms that maintain the integrity of the healthy mucosa are the supply of oxygen and nutrients and the removal of H' ions and waste products by the blood circulation. Processes of mucosal repair such as the restitution (rapid repair) of gastric and duodenal mucosa are now well recognized, and the role of the immune system in mucosal defence is an important area of further research. This volume is based on the sixth Acta Medica Scandinavica Symposium on Gastrointestinal lon Transport and Protection. It was attended by internationally eminent clinical and research scientists and held at the Biomedical Center, Uppsala, Sweden on 5-8 July 1989. The first section of the symposium focuses on cellular mechanisms and control of gastrointestinal acid and base secretion. The identification of the H', K+-ATPase in the secretory membrane of the gastric parietal cell, and knowledge of the intriguing relationship of this enzyme with the transport of H+, K+ and C1ions has contributed greatly to our understanding of ion transport processes. The delineation of the acid secretory process and its control has, furthermore, resulted in the development of new and more efficient drugs for the treatment of ulcer disease. Secretion and diffusion of bicarbonate and the removal of local acid by the circulation are important mechanisms in the defence of oesophageal, gastric, and duodenal mucosa, as well as in the repair of these tissues. The luminal surface of the gastrointestinal tract is covered by a layer of mucus gel which has an important role in function and protection. These topics are discussed in two sections of the symposium. Bicarbonate secretion by the duodenal mucosa is reported to be deficient in patients with chronic and acute duodenal ulcer disease, and the gastric mucus of patients with gastric ulcer disease shows some properties that are distinct from those of the mucus in healthy volunteers. An intriguing issue is the role of neural influence on gastroduodenal mucosal defence. The physiological role of secretion in the small intestine is to dilute damaging contents in the lumen. The simultaneous increase in motility further decreases damage by distributing the diluted contents over a greater mucosal area. The stimulation of intestinal secretion and motility by endogenous mechanisms or bacterial toxins is also a major cause of diarrhoea1 disease. Intestinal secretion and permeability are discussed in the last section of the symposium. Studies of the role of eicosanoids and the influence of extrinsic and mucosal intrinsic nerves will probably provide new methods for treatment of intestinal disease. The Journal of Internal Medicine (formerly Acta Medica Scandinavica) has sponsored annual international symposia since 1984, promoting Nordic Medicine and emphasizing the interdependence between clinical and basic research. We wish to thank the journal and in particular its Editor, Professor Lars Erik Bottiger, for making this symposium possible and for generous support. G u N N A R F L E M S T R O M, President L E N A H o L M, Secretary General