Chemiluminescence of ischaemic and reperfused intestine in vivo.

Low level chemiluminescence of exposed rat intestine was measured during occlusive ischaemia and reperfusion. Spontaneous emission of in vivo rat intestine (10 +/- 1 cps/cm2) decreased almost to zero in animals subjected to ischaemia and when the period of ischaemia lasted only two minutes, chemiluminescence increased beyond control levels (39%, three minutes after reperfusion) at intestine deligation. This overshoot did not occur when rats were pretreated with allopurinol (40 + 100 mg/kg bw). The ratio of xanthine dehydrogenase to xanthine oxidase activities was 3.46 in preischaemic intestine samples. The same ratio was changed to 0.35 in samples subjected to two minutes of ischaemia. As chemiluminescence appears to reflect the steady state level of singlet oxygen, which in turn derives from the steady state level of peroxy radicals, these results agree with the view that oxygen radicals derived from the xanthine oxidase reaction are involved in the cellular damage produced after ischaemia and reoxygenation in the intestine.