Changes in gastric mucosal permeability induced by haemorrhagic shock in the anaesthetized rat: Modulation by acid

Gastric mucosal damage induced by haemorrhagic shock in the anaesthetized r at has been evaluated by studying changes in capillary-to-lumen clearance o f fluorescein isothiocyanate (FITC)-labelled dextran. Haemorrhagic shock (20 min ischaemia + 20 min reperfusion) induced a signif icant increase in blood-to-lumen permeability to FITC-dextran of different molecular weight (10 000, 40 000 and 70 000) without modifying the macrosco pic integrity of the gastric mucosa, The increase in vascular permeability was dependent on the time of administration of the tracer and was correlate d with an elevation of the protein content of the gastric lumen. Intravenou s administration of the secretagogue pentagastrin (20 or 50 mu g kg(-1) h(- 1)) did not significantly modify the vascular permeability to dextran in co ntrol animals or in animals subjected to haemorrhagic shock. When the intra luminal pH was reduced by intragastric administration of acidic saline solu tion, only pH 1, which itself induced the appearance of macroscopic mucosal lesions, significantly increased vascular permeability to dextran, both in control animals and in animals subjected to haemorrhagic shock. These findings suggest that stress induced by haemorrhagic shock increases vascular gastric permeability to dextran, by an acid-independent mechanism, without affecting the macroscopic integrity of the gastric mucosa.