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 t o concurrent lipid peroxidation are believed to be important factors i n 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 nifed ipine. Therefore, we investigated whether nifedipine could inhibit lip id peroxidation in a nonenzymatic active oxygen-generating system, uti lizing rat crude myocardial membranes, and compared its effect with th ose of propranolol, nisoldipine, and diltiazem. Nifedipine and diltiaz em had no inhibitory effects on the lipid peroxidation of myocardial m embranes. 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 an tiperoxidant mechanisms, involving both preventive and chain-breaking properties.