Background
Acute mesenteric ischemia is a life-threatening surgical condition, which presents a great challenge to clinicians due to its difficult diagnosis and high mortality. It is associated with intestinal ischemia-reperfusion (IR) injury, which may be ameliorated by postconditioning. Aim of the current study was to investigate the optimal postconditioning algorithm in a rat model of intestinal IR.

Materials and Methods
Male Wistar rats were randomized into five groups (n=10),: 1) sham-operated 2) IR and three differently chosen protocols of postconditioning: 3) PC10 4) PC30 5) PC60. Postconditioning was performed following 60 minutes of mesenteric ischemia at the very onset of 60 minutes of reperfusion. Arterial blood pressure and mucosal microcirculatory flow were registered throughout the whole experiment, whereas portal venous pH was measured at the early stages of reperfusion. Finalizing reperfusion, blood and tissue samples were taken for further histopathological, and laboratory measures involving serum lactate-dehydrogenase, -creatinine- kinase, -TNF-x, -IL-6, and a detailed mucosal redox panel.

Results
The two shorter and more dynamic postconditioning algorithms led to improved microcirculatory flow, and a delayed decay of portal venous acidosis. In comparison with the IR group, histolopathological alterations, serum necroenzyme- and proinflammatory cytokine levels were significantly attenuated, whereas the mucosal redox panel was significantly enhanced in the two postconditioned groups, respectively. Apart from similar tendentious characteristics, the third, longer interval postconditioning algorithm led to no significant changes.

Conclusion
Following mesenteric IR, the shorter-, and intermediate-interval postconditioning algorithms conferred significant protective effects, which was not observed when applying the long-interval algorithm.