ENALAPRIL AND CAPTOPRIL ENHANCE ANTIOXIDANT DEFENSES IN MOUSE-TISSUES

This study was conducted to investigate a possible systemic effect of angiotensin-converting enzyme inhibitors (ACEi) on tissue antioxidant defenses. CF1 mice (4-mo-old females) were administered either water ( control) or water containing enalapril (20 mg/l) or captopril (50 mg/l ) during 11 wk. Neither enalapril nor captopril treatment had an effec t on body mass or brain, kidney, or heart weight relative to controls. CuZn-superoxide dismutase (SOD) activity was increased by enalapril t reatment in kidney medulla (27%), heart (24%), and erythrocytes (19%) and by captopril treatment in kidney medulla (43%) and heart (54%) rel ative to controls. Mn-SOD and catalase activities were unaffected by e ither treatment. Enalapril, but not captopril treatment, increased Se- glutathione peroxidase activity in renal medulla (19%). Nonenzymatic a ntioxidant defenses, evaluated by tert-butyl hydroperoxide-initiated c hemiluminescence (HICL), were enhanced in kidney cortex (48%) by enala pril and in brain by enalapril (44%) or captopril (36%) treatment rela tive to controls. As evaluated in vitro by HICL and thiobarbituric aci d-reactive substances formation, captopril had a free radical scavenge r activity, whereas neither enalapril nor lisinopril was effective. Th ese results suggest that ACEi may protect tissues from oxidative damag e by increasing enzymatic and nonenzymatic antioxidant defenses.