PROTECTIVE ROLE OF ANION CHANNEL BLOCKER IN LIPID-PEROXIDATION CAUSEDBY H2O2 IN MICROSOMES OF BOVINE PULMONARY ARTERIAL SMOOTH-MUSCLE TISSUE

The role of hydroxyl radical (OH.) in H2O2-mediated stimulation of lip id peroxidation in microsomes of bovine pulmonary arterial smooth musc le tissue and the protective effects of DIDS, the anion channel blocke r have been studied. Treatment of microsomes with H2O2 (1 mM) stimulat e iron release, OH. production and lipid peroxidation. Pretreatment wi th DFO (an iron chelator) or DMTU (a hydroxyl radical scavenger) preve nts OH. production and thereby reduces lipid peroxidation without any appreciable reduction of iron release. Simultaneous treatment of eithe r DFO or DMTU with H2O2 significantly reduces lipid peroxidation and p revents OH. production without any significant reduction of iron relea se. However, addition of DFO or DMTU 2 min after treatment of the micr osome with H2O2 does not produce any significant reduction of lipid pe roxidation. OH production and iron release. Pretreatment of microsomes with DIDS markedly reduces the stimulation of lipid peroxidation with out appreciably altering the increase in OH. production and iron relea se caused by H2O2.