Dynamic 13C NMR analysis of pyruvate and lactate oxidation in the in vivo canine myocardium: evidence of reduced utilization with increased work
| Autor: | Dipti P. Rath, Zongcheng Jiang, Pierre-Marie Robitaille, Hui Zhu, Robert L. Hamlin, Xiaoxin Tong |
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| Rok vydání: | 1997 |
| Předmět: |
Magnetic Resonance Spectroscopy
Citric Acid Cycle Glutamic Acid Dichloroacetic acid Biology chemistry.chemical_compound Lactate oxidation Dogs In vivo Pyruvic Acid Animals Radiology Nuclear Medicine and imaging Carbon Radioisotopes Lactic Acid Alanine chemistry.chemical_classification Dichloroacetic Acid Myocardium Glutamate receptor Heart Tricarboxylic acid Pyruvate dehydrogenase complex Citric acid cycle Biochemistry chemistry Oxidation-Reduction |
| Zdroj: | Magnetic resonance in medicine. 38(6) |
| ISSN: | 0740-3194 |
| Popis: | In this work, substrate selection was monitored in the left ventricle of the canine myocardium by following pyruvate and lactate oxidation under in vivo conditions at basal and elevated workloads. These studies were conducted in the open chest model using dynamic 13C NMR techniques in the presence and absence of dichloroacetic acid (DCA), a well-known activator of pyruvate dehydrogenase (PDH). Following the infusion of (3-(13)C) pyruvate or (3-(13)C) lactate into the left anterior descending artery, highly variable 13C enrichments of glutamate, alanine, aspartate, and citrate were noted under low (RPP14,500 mmHg/min), intermediate (RPP = 15,000-25,000 mmHg/min), and high (RPP25,500 mmHg/min) rate pressure products (RPP). At low workloads, the myocardium typically oxidized the infused (3-(13)C) pyruvate or (3-(13)C) lactate and incorporated the labeled carbon into the glutamate pool as expected. However, in a few notable instances (n = 3), 13C-enriched pyruvate and lactate were unable to label the glutamate pool under in vivo conditions even at the lowest RPPs, indicating a lack of selection for these substrates by the tricarboxylic acid (TCA) cycle. Nonetheless, the levels of glutamate C4 enrichment observed at low workloads could usually be enhanced by infusion of DCA. Importantly, 13C NMR extract analysis revealed that (3-(13)C) pyruvate or (3-(13)C) lactate labeling of the glutamate pool was reduced (20%) at high workloads in spite of increased DCA concentrations. |
| Databáze: | OpenAIRE |
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