Adenosine enhanced preconditioning prevents apoptosis in the small intestine and inhibits bacterial translocation

Introduction

Previously it has been shown that ischemic preconditioning could increase the tolerance of intestinal tissue to ischemia [1]. In this study we investigated the effects of pharmacological preconditioning with adenosine infusion on intestinal ischemia/reperfusion (I/R) injury and bacterial translocation. We also evaluated the presence of any additive effects of adenosine administration when used together with ischemic preconditioning.

Materials and methods

Forty-six Sprague-Dawley rats were used, and rats were randomly divided into five groups: Group I, sham operated controls: only laparotomy was performed; Group II, ischemia-reperfusion (I/R): superior mesenteric artery was clamped for 40 min to induce ischemia in the small bowel that was followed by 24 hours of reperfusion; Group III, ischemic preconditioning (IPC): two cycles of 5 min of ischemia-5 min of reperfusion were performed prior to the I/R schedule given in Group II; Group IV, pharmacologic preconditioning (Ado): adenosine at a dose of 1000 μg/kg was infused from the internal jugular vein prior to the I/R schedule given in Group II; Group V, adenosine enhanced IPC: adenosine was infused as in Group IV prior to ischemic preconditioning that was followed by a 40 min ischemia-24 hours reperfusion schedule. Twenty-four hours later, to evaluate whether the I/R induced intestinal injury and bacterial translocation, blood, liver, spleen, and mesenteric lymph node (MLN) specimens were obtained under sterile conditions for microbiological analysis. Samples of jejunum were removed for histopathological evaluation by Chiu scoring and determination of apoptotic cell number is achieved by the staining of M30 monoclonal antibody.

Results

In the I/R group, the incidence of bacteria-isolated MLNs, spleen, and liver was significantly higher than other groups (P < 0.05). IPC, Ado and Ado + IPC prevented I/R-induced bacterial translocation and they significantly reduced the I/R-induced intestinal injury and intestinal epithelial apoptosis.

Conclusions

This is the first study showing that adenosine administration was as effective as ischemic preconditioning in inducing ischemic tolerance and in preventing bacterial translocation in the rat intestine. However, there was no enhancement of IPC with prior adenosine infusion.