Gastric mucosal defense and cytoprotection.

The gastric mucosa is continuously exposed to many noxious factors and substances. 'Mucosal defense' is a term used to describe the various factors that permit the mucosa to remain intact despite its frequent exposure to substances with a wide range of temperature, pH and osmolarity, as well as to substances with detergent or cytotoxic actions, and bacterial products capable of causing local and systemic inflammatory reactions. Mucosal defense is multifactorial and can be modulated by a wide range of substances and mediators. We review basic components of gastric mucosal defense. Knowledge regarding gastric mucosal defense mechanisms has let to the development of current and potential future therapies to reduce gastrointestinal injury. The concept of 'cytoprotection' has been developed to describe the ability of pharmacologic agents to reduce damage to the stomach induced by ulcerogenic or necrotizing agents.