PROTECTIVE ROLE OF HEMOPEXIN ON HEME-DEPENDENT LUNG OXIDATIVE STRESS

Tert-butylhydroperoxide (t-BOOH)-dependent chemiluminescence of perfused rat lungs increased by almost 500 % upon addition of heme (from 297 ± 28% to 1204 ± 125% of control, p < 0.01 vs no heme). Preincubation with hemopexin significantly decreased the heme-stimulated chemiluminescence to 779 ± 155% of control (p < 0.01) When hemopexin was replaced with rat albumin heme- stimulated chemiluminescence decreased to 1007 ± 104% (not significantly different from results with heme alone). In vitro studies showed that hemopexin did not decrease chemiluminescence from bovine serum albumin oxidation (493 ± 94% compared to 292 ± 81% of control in the absence of hemopexin) and that the heme-hemopexin mixture also emitted light when exposed to t-BOOH (264 ± 66% of control). These results suggest that hemopexin specifically inhibits some of the oxidative reactions catalyzed by free heme and may have a protect tissue oxidation in conditions in which heme release occurs (i.e., stroke). © 1993 Academic Press, Inc.