TOTAL ANTIOXIDANT CAPACITY OF SERUM INCREASED IN EARLY BUT NOT LATE PERIOD AFTER INTESTINAL ISCHEMIA IN RATS

The ischemia of small intestine was induced in anesthetized Wistar rat s by occluding the superior mesenteric artery for 45 min and then the reperfusion was set. Serum samples were obtained at the end of the isc hemic period and also during early (1 to 4 h) and late postischemic pe riod (1 to 4 d). The total antioxidant capacity (TRAP) of serum sample s was evaluated using luminol enhanced chemiluminescence. The increase d mobilization of phagocytic cells and the release of reactive oxygen species into the circulation was observed from the first and second ho ur of the postischemic period, respectively. Nevertheless, the activit y of natural antioxidant mechanisms of serum was already elicited at t he end of the ischemic period. Furthermore, the TRAP of serum increase d with the increasing duration of early postischemic period. Among the antioxidants studied, urate and ascorbate concentrations exerted the highest correlation with TRAP, but 31.6% of the total antioxidant capa city remained for the activity of an unidentified antioxidant(s). Afte r being exhausted, the TRAP of serum oscillated around the preoperatio n level at days 1-4 of the postischemic period. The increase in total antioxidant capacity of serum induced by oxidative stress was sufficie nt to prevent lipoperoxidation both in serum and intestinal tissue. (C ) 1998 Elsevier Science Inc.