Role of changes in tissular nucleotides on the development of apoptosis during ischemia/reperfusion in rat small bowel.

The aim of this study was to evaluate whether xanthine and adenosine, substances modified proportionally to the duration of ischemia, can determine cell demise (apoptosis/necrosis) during intestinal ischemia/reperfusion (I/R) and to determine the role of nitric oxide (NO) during this process. The following experimental groups were studied: I, cold ischemia; I+X, effect of xanthine; I+T, effect of adenosine (blocking its receptor by theophylline); I+A, effect of excess adenosine; I+T+X, effect of xanthine alone, and I+T+ spermine NONOate (NONOs), I+A+NONOs, I+X+NONOs, role of NO. DNA fragmentation, xanthine/adenosine levels, caspase-3 activity, NO generation, and histological analysis were measured in tissue samples. The rats treated with xanthine or adenosine showed increased levels of caspase-3 activity and DNA fragmentation. In contrast, theophylline-treated rats showed decreased levels of DNA fragmentation and tended to show lower mean values of caspase-3 activity. Administration of xanthine or NONOs to theophylline-treated rats reversed these effects. The results of histological evaluation were in agreement with these previous results. In conclusion, the present study indicates that xanthine and adenosine induced an apoptotic response during cold ischemic preservation of rat small intestine. In particular, the action of adenosine on apoptotic events was mediated by NO. We consider that identification of the role of these factors may help to define the best conditions of tissue preservation before intestinal transplantation.