ACTIVATED POLYMORPHONUCLEAR LEUKOCYTES INCREASE LOW-LEVEL CHEMILUMINESCENCE OF ISOLATED-PERFUSED RAT LUNGS

Low-level chemiluminescence was measured in isolated perfused rat lungs subjected to different types of oxidative stress: perfusion with tert-butyl hydroperoxide (t-BOOH) or stimulation of polymorphonuclear cells (PMN). The time required for t-BOOH-dependent lung chemiluminescence to return to background levels was proportional to the concentration of t-BOOH. From the half times of the decay at different t-BOOH concentrations, we estimated that the lungs metabolize organic peroxides at a rate of 0.045 mM/min. Use of a high dose of t-BOOH (3 mM) or pretreatment of lungs with 1,3-bis(2-chloroethyl)-nitrosourea (100 mug/ml) to inhibit glutathione reductase produced chemiluminescence that was much greater and did not decay. Stimulation of 5 X 10(7) PMN with lug of phorbol myristate acetate resulted in significant increases in chemiluminescence that occurred in the absence of a significant lung weight gain or measurable lipid peroxidation. Perfusion of isolated lungs with superoxide dismutase (100 U/ml) completely inhibited the chemiluminescence response to PMN activation, whereas treatment with 100 muM U-74389F, a lipid-soluble antioxidant, also significantly decreased PMN-dependent chemiluminescence. Neither catalase (2,000 U/ml) nor 100 muM U-78518F, a water-soluble antioxidant, decreased chemiluminescence after PMN activation. These results indicate that low-level chemiluminescence is a sensitive indicator of oxidative stress in the isolated perfused rat lung and provides a tool for devising and characterizing the effectiveness of antioxidant interventions.