Pathways, mediators and mechanisms of gastroduodenal mucosal injury.

This review provides evidence that gastroduodenal mucosal injury is a complex process because of the heterogeneous structure and multiple functions of the gut. The action of exogenous etiologic agents is usually mediated in part, or amplified by endogenous mediators which very often exert biphasic, i.e., damaging and protective effects. The pathogenetic pathways involve direct/indirect chemical injury, vascular damage and its consequences, and acute or chronic inflammatory processes following infectious, chemical or ischemic injury. The role of oxygen, free radicals, calcium and proteases as well as the components and forms of gastroduodenal injury, e.g., reversible and irreversible cell injury, tissue necrosis, acute and chronic inflammation are also briefly discussed. Only a slight or moderate direct cytoprotection was demonstrated in vitro using isolated, mixed rat gastric mucosal cells by the known gastroprotective drugs including PG and SH compounds. Thus, the terms of organo or gastroprotection are more descriptive then the misleading "gastric cytoprotection".