ABSENCE OF ANTIOXIDANT EFFECTS OF NIFEDIPINE AND DILTIAZEM ON MYOCARDIAL MEMBRANE LIPID-PEROXIDATION IN CONTRAST WITH THOSE OF NISOLDIPINE AND PROPRANOLOL

Both the production of active oxygen species and cellular damage due to concurrent lipid peroxidation are believed to be important factors in the pathogenesis of cardiovascular diseases and the ageing process. Since cardiovascular drugs are often administered over a long term, it might be advantageous if they reduced lipid peroxidation. There have been conflicting reports concerning the antiperoxidant effect of nifedipine. Therefore, we investigated whether nifedipine could inhibit lipid peroxidation in a nonenzymatic active oxygen-generating system, utilizing rat crude myocardial membranes, and compared its effect with those of propranolol, nisoldipine, and diltiazem. Nifedipine and diltiazem had no inhibitory effects on the lipid peroxidation of myocardial membranes. In contrast, nisoldipine and propranolol had a concentration-dependent antiperoxidant effect, with IC50 values of 28.2 and 50.1 mu M, respectively. In addition, nisoldipine appeared to possess dual antiperoxidant mechanisms, involving both preventive and chain-breaking properties.