Phospholipase A(2) secretion during intestinal graft ischemia

The time-dependent appearance of phospholipase A, (PLA,) activity in the preservation media of ischemic rat intestinal grafts is described. In controls, Ca2+-dependent, secretory PLA(2) activity accumulated rapidly during the first 6 hr of ischemia, followed by a linear increase for up to 48 hr. LDH levels, by contrast, increased linearly throughout the 48 hr of ischemia. Addition of inhibitors of PLA,, cyclooxygenase, and lipooxygenase blocked accumulation of PLA(2), but not LDH. PX-13, a novel PLA(2) inhibitor, was most effective: 40 mu M inhibited release by 86%, while 25 mu M indomethacin (cyclooxygenase blocker) or nordihydroguiaretic acid (lipooxygenase blocker) inhibited 41 and 36%, respectively. That appearance of PLA, activity, but not LDH, is attenuated by inhibitors of the eicosanoid cascade suggests a secretory event rather than leakage from dying cells. The secreted PLA, is most likely the proinflammatory sPLA(2) that has been implicated as a stress-induced protein and priming agent in ischemia-reperfusion injury.