title: An intact small animal model of myocardial ischemia-reperfusion: Characterization of metabolic changes by hyperpolarized 13C MR spectroscopy.
abstract: Hyperpolarized carbon-13 magnetic resonance spectroscopy ((13)C MRS) enables the sensitive and noninvasive assessment of the metabolic changes occurring during myocardial ischemia-reperfusion. Ischemia-reperfusion models using hyperpolarized (13)C MRS are established in heart preparations ex vivo and in large animals in vivo, but an in vivo model in small animals would be advantageous to allow the study of reperfusion metabolism with neuroendocrine and inflammatory responses intact with the option to perform a greater number of experiments. A novel intact rat model of ischemia-reperfusion is presented that incorporates hyperpolarized (13)C MRS to characterize reperfusion metabolism. Typically, in an in vivo model, a tissue input function (TIF) is required to account for apparent changes in the metabolism of injected hyperpolarized [1-(13)C]pyruvate resulting from changes in perfusion. Whereas the measurement of a TIF by metabolic imaging is particularly challenging in small animals, the ratios of downstream metabolites can be used as an alternative. The ratio of [(13)C]bicarbonate:[1-(13)C]lactate (RatioBic/Lac) measured within 1-2 min after coronary release decreased vs. baseline in ischemic rats (n = 10, 15-min occlusion, controls: n = 10; P = 0.017 for interaction, 2-way ANOVA). The decrease in oxidative pyruvate metabolism [RatioBic/Lac(Ischemia)/RatioBic/Lac(Baseline)] modestly correlated with area at risk (r = 0.66; P = 0.002). Hyperpolarized (13)C MRS was also used to examine alanine production during ischemia, which is observed in ex vivo models, but no significant change was noted; metrics incorporating [1-(13)C]alanine did not substantially improve the discrimination of ischemic-reperfused myocardium from nonischemic myocardium. This intact rat model, which mimics the human situation of reperfused myocardial infarction, could be highly valuable for the testing of new drugs to treat reperfusion injury, thereby facilitating translational research.
authors.affiliation: Division of Cardiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland; Center for Biomedical Imaging (CIBM), Lausanne, Switzerland; Cardiac MR Center, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Hikari A I
authors.initials: HA
authors.lastname: Yoshihara
authors.affiliation: Institute of Physics of Biological Systems, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland; Center for Biomedical Imaging (CIBM), Lausanne, Switzerland;
authors.forename: Jessica A M
authors.initials: JA
authors.lastname: Bastiaansen
authors.affiliation: Cardiovascular Assessment Facility, Lausanne University Hospital (CHUV), Lausanne, Switzerland;
authors.forename: Corinne
authors.initials: C
authors.lastname: Berthonneche
authors.affiliation: Institute of Physics of Biological Systems, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland; Center for Biomedical Imaging (CIBM), Lausanne, Switzerland;
authors.forename: Arnaud
authors.initials: A
authors.lastname: Comment
authors.affiliation: Division of Cardiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland; Cardiac MR Center, Lausanne University Hospital (CHUV), Lausanne, Switzerland jurg.schwitter@chuv.ch.
authors.forename: Juerg
authors.initials: J
authors.lastname: Schwitter
mesh_terms: D000409:Alanine / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002247:Carbon Isotopes; D004195:Disease Models, Animal; D006439:Hemodynamics; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D007773:Lactates / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D009490:Neurosecretory Systems / Q000378:metabolism / Q000473:pathology; D010084:Oxidation-Reduction; D011773:Pyruvates / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001639:Bicarbonates; D002247:Carbon Isotopes; D007773:Lactates; D011773:Pyruvates; D000409:Alanine
keywords: carbon-13; dynamic nuclear polarization; heart; hyperpolarization; magnetic resonance spectroscopy