The effects of bis(2-propoxyethyl)-1,4-dihydro-2,6-dimethyl-4-*3-nitrophenyl)-3,5-pyridine dicarboxylate (niludipine), a newly-synthesized calcium antagonist related in chestical structure to nifedipine, on the ischemic myocardium were studied in eight anesthetized, open-chest dogs, mainly by the simultaneous measurement of regional myocardial blood flow (MBF) and regional myocardial function. The ischemic myocardium was prepared by partial occlusion of the left circumflex coronary artery, and niludipine was given i.v. at a dose of 5 micrograms/kg. MBF was measured by the radioactive microsphere method and regional myocardial function was assessed by measurement of myocardial segment length. Measurements were also taken of aortic pressure, left ventricular pressure, ascending aortic blood flow, and left circumflex coronary blood flow. Niludipine decreased left ventricular contractility, dilated resistance vessels and reduced heart rate. MBF, measured 5 min after the drug was administered, increased in both the ischemic and the non-ischemic myocardium. Improvement in regional myocardial function was observed in the ischemic myocardium 5 min later, when aortic pressure had returned to nearly the pre-administration level. Thus, the results of the study suggest that niludipine improves the balance between myocardial energy supply and demand in the ischemic myocardium when there is little change in aortic pressure, and we concluded that niludipine exerts a beneficial effect on the ischemic myocardium