Nuclear magnetic resonance evaluation of metabolic and respiratory support of work load in intact rabbit hearts
| Autor: | Edward D. Lewandowski |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
medicine.medical_specialty
Magnetic Resonance Spectroscopy Anabolism Phosphocreatine Physiology Cellular respiration Citric Acid Cycle Biology Acetates In Vitro Techniques Mitochondria Heart Potassium Chloride Nuclear magnetic resonance Adenosine Triphosphate Glutamates Internal medicine Respiration medicine Animals Carbon Radioisotopes chemistry.chemical_classification Glutamate receptor Isoproterenol Models Cardiovascular Tricarboxylic acid Metabolism Citric acid cycle Perfusion Endocrinology chemistry Steady state (chemistry) Rabbits Cardiology and Cardiovascular Medicine Phosphorus Radioisotopes |
| Zdroj: | Circulation research. 70(3) |
| ISSN: | 0009-7330 |
| Popis: | Pre-steady-state 13C nuclear magnetic resonance (NMR) spectra can provide a nondestructive probe of metabolic events associated with the physiology of intact organs. Therefore, the relation between phosphorylation state and intermediary metabolism in rabbit hearts, oxidizing [2-13C]acetate, was examined with a combination of 31P and 13C NMR. Multiple enrichment of the tissue glutamate pool with 13C as an index of metabolic turnover within the tricarboxylic acid cycle was readily observed as a function of work load. Dynamic changes in pre-steady-state 13C spectra evolved according to work load and correlated closely to respiratory rate in rabbit hearts perfused 1) under normal conditions (n = 7), 2) at basal metabolic rates (20 mM KCl arrest, n = 5), 3) and at heightened contractile state (10(-7) M isoproterenol, n = 7). The ratio of signal intensity arising from the secondary labeling sites within glutamate (C-2 and C-3) to that of the initial labeling site (C-4) reached steady state within 8.5 minutes in isoproterenol-treated hearts versus 18.5 minutes in control hearts. Work load did not affect glutamate concentration or fractional enrichment at the C-4 position, although an unlabeled fraction of glutamate persisted. Arrested hearts displayed slowed evolution of steady-state 13C enrichment with increased contributions from anaplerotic sources for tricarboxylic acid intermediate formation (32%) as compared with control (9%). Thus, the response of mitochondrial dehydrogenase activity to the demands of cardiac performance is likely to influence the recruitment of anabolic sources supplying the tricarboxylic acid cycle.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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