The Isoproterenol Stress Test in Unanesthetized Atherosclerotic Rabbits

Summary

Isoproterenol infusion was employed as a cardiac stress test in unanesthetized, atherosclerotic rabbits. In addition to tachycardia, isoproterenol infusion caused ischemic S-T segment depression of the electrocardiogram. Propranolol (0.1 and 1 mg/kg, iv), given during isoproterenol infusion, reversed the tachycardia and S-T segment depression. Nitroglycerin (100 μg/kg, iv) reversed the ischemic S-T segment depression but did not affect the tachycardia. Dipyridamole (250 μg/kg) tended to exacerbate S-T segment depression, and had no effect on the tachycardia. The effects of nitroglycerin and dipyridamole in these animals correlated well with clinical results, i.e. nitroglycerin had a beneficial effect whereas dipyridamole did not. We conclude that the stress of isoproterenol infusion is as useful as atrial pacing in this experimental model of angina pectoris.