ATP-MGCL(2) REDUCES INTESTINAL PERMEABILITY DURING MESENTERIC ISCHEMIA

ATP-MgCl2 has been demonstrated to have beneficial attributes in numer ous models of organ ischemia. In this study we examined whether ATP-Mg Cl2 could decrease permeability in ischemic segments of rat ileum. Rea l segments (nonischemic and ischemic) from the same rat were cannulate d and perfused, and the plasma to lumen clearance of Cr-51-EDTA was me asured. Ischemia increased permeability from a baseline value of 0.59 +/- 0.14 (mean +/- SEM in ml/min/g dry wt of intestine) to 1.10 +/- 0. 14 at 90 min (n = 12), significantly higher than that of the nonischem ic segments (0.55 +/- 0.07) at 90 min (P < 0.05). This was associated with a significant reduction in blood how from 0.84 +/- 0.08 (n = 4) ( mean +/- SEM ml/min/g wet wt of intestine) to 0.16 +/- 0.06 (n = 4) (P < 0.05) as measured by labeled microspheres. Rats receiving ATP-MgCl2 (100 mu mol) (n = 8) pretreatment showed no increase in clearance ove r 90 min (baseline 0.69 +/- 0.07; 90 min 0.70 +/- 0.07) and no signifi cant difference in blood how from untreated ischemic segments (0.21 +/ - 0.9) (n = 4). Tissue ATP levels determined enzymatically were signif icantly reduced by 5 min postischemia to 4.19 +/- 0.35 (n = 7) (P < 0. 05) from a control value of 6.77 +/- 0.77 mu mol/g dry wt (n = 14). AT P levels remained depressed at 30 min (3.45 +/- 0.35) and 90 min (3.38 +/- 0.26). ATP-MgCl2 treatment did not significantly alter these tiss ue ATP levels. These data indicate that ATP-MgCl2 prevents the increas e of Cr-51-EDTA permeability during ischemia without alterations in ti ssue ATP levels or increases in intestinal blood how. (C) 1996 Academi c Press, Inc.