Effects of oxodipine and nitrendipine on the size of experimental myocardial infarct in the rat.

The protective effect of either oxodipine or nitrendipine (4 mg/kg/twice daily, orally), two dihydropyridines exhibiting calcium channel-blocking properties, against induced infarct-like lesions was examined. Experimental myocardial infarct-like lesions were induced in rats by subcutaneous injection of isoproterenol (0.5 mg/kg). The lesions were mainly located in subendocardial areas of the free wall of the left ventricle, and were intramural at the apex and ventricular septum. Pretreatment with oxodipine significantly reduced the infarct size in the apical and basal myocardium (P < 0.05). Possible explanations for the lack of effect of nitrendipine pretreatment are discussed.