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Figure 1 Percent change in arterial diameter in response to different doses of acetylcholine (ACh) in post-acute myocardial infarction (AMI) patients and the control group. At the maximum concentration of ACh the post-AMI patients showed a considerable vasoconstriction response in the infarct-related artery, indicative of endothelial dysfunction, while the control group showed a slight vasodilation response. Both groups exhibited a vasodilation response to nitroglycerin (NTG), suggesting that the nonendothelium-dependent vasodilation is conserved.