Are gastric, jejunal, or both forms of enteral feeding gastroprotective during stress?

Background. Clinical data suggest enteral nutrition prevents stress ulcerat ion and intragastric nutrients prevent restraint-induced gastric injury. Th e purpose of these studies was to determine if jejunal nutrients can protec t without gastric contact and to determine if gastric pH, motility, or muco sal perfusion is affected. Methods. In Experiment 1, 27 rats were restrained for 2 h at room temperatu re followed by 2 h in cold (4 degrees C), with intragastric (IG) or intraje junal (IJ) 2 ml/h infusions of saline or 25% glucose. Gastric lesions, pH, volumes, and glucose concentrations were measured postmortem. In Experiment 2, 23 rats had gastric strain gauges implanted >5 days prior to a 0.5 ml/h IG or IJ infusion during stress. In Experiment 3, 40 rats were anesthetize d for laser Doppler measurements of gastric mucosal perfusion and arterial catheter monitoring of systemic hemodynamics. Rats received 0.5-ml boluses of concentrated glucose or saline IG or IJ, and were monitored for 60 min. Results. (1) The 2 ml/h IJ and IG glucose infusions prevented gastric injur y, but the elevated gastric glucose concentrations suggested equal gastric contact. (2) The 0.5 ml/h glucose IG and IJ infusions decreased gastric inj ury without reflux of the IJ glucose into the stomach and suppressed stress -induced hypercontractility, but not acidity. (3) Systemic perfusion pressu res were unaffected by enteral glucose. IG glucose had little effect on gas tric mucosal perfusion, while IJ glucose decreased gastric perfusion within 5 min. Conclusions. These studies show that large volumes of enteral glucose preve nt restraint injury but IJ glucose refluxes into the stomach. The gastropro tective effects of small, nonrefluxing volumes of IJ glucose associated wit h suppression of stress-induced gastric hypercontractility, but not with su ppressed acidity or enhanced perfusion. (C) 2000 Academic Press.