Evaluation of fatty acid metabolism in hearts after ischemia-reperfusion injury using a dual-isotope autoradiographic approach and tissue assay for metabolites of tracer. |
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Authors: | Norio Igarashi Takashi Nozawa Nozomu Fujii Bun-ichi Kato Makoto Nonomura Akira Matsuki Teruo Nakadate Akihiko Igawa Hidetsugu Asanoi Minoru Inoue Hiroshi Inoue |
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Institution: | Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan. |
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Abstract: | We investigated whether changes in myocardial uptake of fatty acid tracer after reperfusion following transient myocardial ischemia were closely related to alterations in intracellular fatty acid oxidation. METHODS: Using a fatty acid tracer of (131)I- and (125)I-labeled 15-(p-iodophenyl)-9-methylpentadecanoic acid (9MPA), the myocardial uptake and metabolites were determined by dual-tracer autoradiography and thin-layer chromatography in rats 3 or 14 d after reperfusion following 5 or 15 min of ischemia induced by coronary artery ligation. RESULTS: 9MPA metabolites processed via beta-oxidation were lower in the ischemic region (IR) than in non-IR 3 d after 5 min of ischemia, despite no reduction of tracer uptake in IR. Oxidation of 9MPA was recovered 14 d after 15 min of ischemia in association with normalization of tracer uptake in IR, whereas both uptake and oxidation of 9MPA were markedly impaired 3 d after 15 min of ischemia, accompanied by slow clearance of myocardial tracer. CONCLUSION: Normal uptake of fatty acid tracer early after reperfusion does not always imply preserved intracellular fatty acid oxidation. However, reduction of tracer uptake might reflect impaired fatty acid oxidation. |
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