Hearts which are made ischemic for relatively short periods of time, and then re-perfused, exhibit a temporary decline in tension-generating activity but are not irreversibly injured". Experiments were undertaken to find out whether such "stunned" hearts develop a perfusion defect, and whether chemically heterogeneous Ca(2+)-antagonists provide protection, when used prophylatically. "Stunning" was produced by repetitive 10 minute episodes of ischemia, followed by 15 minutes of reperfusion. The experimental model was the Langendorff-perfused rat heart, and the perfusion buffer was Krebs-Henseleit solution at 37 degrees C. To detect perfusion defects, fuchsin dye was added to the buffer. No evidence of a perfusion defect was obtained. Nevertheless, 10(-8)M nifedipine. 10(-8)M verapamil, 10(-8)M felodipine, and 10(-7)M diltiazem all conferred protection, as gauged by recovery of function after three successive 10 minute episodes of ischemia.