Homocysteine impairs coronary microvascular dilator function in humans

Ahmed Tawakol, Marc A. Forgione, Markus Stuehlinger, Nathaniel M. Alpert, John P. Cooke, Joseph Loscalzo, Alan J. Fischman, Mark A. Creager, Henry Gewirtz

Research output: Contribution to journalArticle

80 Scopus citations

Abstract

OBJECTIVES: We sought to use positron emission tomography (PET) to test the hypothesis that hyperhomocysteinemia adversely effects coronary microvascular dilator function. BACKGROUND: Hyperhomocysteinemia is associated with abnormal endothelium-dependent vasodilation in peripheral human arteries. However, its effect on the coronary, circulation is not known. METHODS: Eighteen healthy humans, age 24 to 56 years, were enrolled in a double-blind, crossover trial. Basal and adenosine-stimulated myocardial blood flow (MBF) was determined by PET: after ingestion of placebo and after methionine-induced hyperhomocysteinemia. Further, brachial ultrasonography was used to assess flow-mediated vasodilation. Additionally, to assess the role of nitric oxide (NO) in adenosine-mediated vasodilation, the MBF response to adenosine was measured in the presence and absence of the NO synthase antagonist NG-monomethyl-L-arginine (L-NMMA) (0.3 mg/kg/min intravenously). RESULTS: Hyperhomocysteinemia resulted in a reduction in the MBF dose-response curve to adenosine (p < 0.05). This was most apparent with low dose adenosine, where MBF augmentation was significantly blunted during hyperhomocysteinemia (1.06 ± 1.00 ml/min/g vs. 0.58 ± 0.78 ml/min/g, placebo vs. methionine, p < 0.05). Similarly, flow-mediated brachial artery vasodilation was impaired during hyperhomocysteinemia (4.4 ± 2.6% vs. 2.6 ± 2.3%, placebo vs. methionine, p < 0.05). In a separate series of experiments, MBF during adenosine was reduced in the presence of L-NMMA (p < 0.05 analysis of variance). This was most apparent at the low dose of adenosine, where MBF response to adenosine was blunted in the presence of L-NMMA (2.08 ± 1.34 ml/min/g vs. 1.48 ± 1.32 ml/min/g, placebo vs. L-NMMA, p < 0.05). CONCLUSIONS: The data, therefore, support the hypothesis that acute hyperhomocysteinemia impairs microvascular dilation in the human coronary circulation as a result of reduced NO bioavailability.

Original languageEnglish (US)
Pages (from-to)1051-1058
Number of pages8
JournalJournal of the American College of Cardiology
Volume40
Issue number6
DOIs
StatePublished - Sep 18 2002

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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