n Carlos, Universidad Complutense de Madrid, Madrid, Spain

Background and Aim: The early protective effect of ischemic preconditioning (PC) on small bowel prior to harvesting and autotransplantation has been shown in animal models. However, little is known about the early impact of PC on intestinal ion transport and barrier function. The aim of this study was to investigate the early functional effects of intestinal PC on porcine ileal mucosa.Material and methods: After obtaining approval from our Animal Ethics Committee, six pigs were anesthetized using a standard protocol and the abdomen was approached through a midline laparotomy. Two contiguous 20-cm segments of small intestine proximal to the ileocecal valve were isolated. One of them was preconditioned by intermittent cross-clamping of the mesentery over 4 cycles of 5-minute ischemia and 10-minute reperfusion whereas the other served as control. Samples were obtained from both segments, immersed in iced-cold buffer and, subsequently, the stripped mucosa was mounted in modified Ussing chambers. Baseline and stimulated transepithelial resistance (TER in Ω x cm2) and short circuit current (Isc in μA x cm-2) were monitored with a dual clamp. Barrier function was investigated with spectrofluoretry using FITC as a probe. H&E staining was used to assess microscopic morphology. Student’s t test was used for statistical analysis.Results: Preconditioning did not alter either baseline electrical barrier properties (TER: 78 ± 5.1 vs 72.9 ± 8.2; n=13, NS) or baseline currents (Isc: 30.9 ± 2.9 vs. 39.5 ± 7.5; n=13,NS). Cyclic nucleotide-activated currents (peak Isc: 47.7 ± 3.4 vs 41.9 ± 2.5 ) or calcium-stimulated secretion (peak Isc: 5.5 ± 2.6 vs 6.2 ± 2.7) were not affected either. However, paracellular permeability assessed by FITC (Fluorescence at 30 min: 222 ± 61.7 counts vs. 65.3 ± 23.0 counts; n=6 p=0.038), was transiently increased. No morphological difference between preconditioned and control mucosa was observed (Figure 1)Conclusions: Intestinal PC does not alter either baseline or stimulated secretion but causes an early increase in permeability in porcine ileal mucosa.