Postnatal expression and activity of the mitochondrial 2-oxoglutarate-malate carrier in intact hearts. 2000

J L Griffin, and J M O'Donnell, and L T White, and R J Hajjar, and E D Lewandowski
Departments of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.

This study examines the functional implications of postnatal changes in the expression of the mitochondrial transporter protein, 2-oxoglutarate-malate carrier (OMC). Online (13)C nuclear magnetic resonance ((13)C NMR) measurements of isotope kinetics in hearts from neonate (3-4 days) and adult rabbits provided tricarboxylic acid cycle flux rates and flux rates through OMC. Neonate and adult hearts oxidizing 2.5 mM [2,4-(13)C(2)]butyrate were subjected to either normal or high cytosolic redox state (2.5 mM lactate) conditions to evaluate the recruitment of malate-aspartate activity and the resulting OMC flux. During development from neonate (3-4 days) to adult, mitochondrial protein density in the heart increased from 19 +/- 3% to 31 +/- 2%, whereas OMC expression decreased by 65% per mitochondrial protein content (P < 0.05). Correspondingly, OMC flux was lower in adults hearts than in neonates by 73% (neonate = 7. 4 +/- 0.4, adult = 2.0 +/- 0.1 micromol/min per 100 mg mitochondrial protein; P < 0.05). Despite clear changes in OMC content and flux, the responsiveness of the malate-aspartate shuttle to increased cytosolic NADH was similar in both adults and neonates with an approximate threefold increase in OMC flux (in densitometric units/100 mg mitochondrial protein: neonate = 25.8 +/- 2.5, adult = 6.0 +/- 0.2; P < 0.05). The (13)C NMR data demonstrate that OMC activity is a principal component of the rate of labeling of glutamate.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008928 Mitochondria Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed) Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D009206 Myocardium The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow. Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D009682 Magnetic Resonance Spectroscopy Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING). In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
D010084 Oxidation-Reduction A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471). Redox,Oxidation Reduction
D010085 Oxidative Phosphorylation Electron transfer through the cytochrome system liberating free energy which is transformed into high-energy phosphate bonds. Phosphorylation, Oxidative,Oxidative Phosphorylations,Phosphorylations, Oxidative
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D002352 Carrier Proteins Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes. Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002952 Citric Acid Cycle A series of oxidative reactions in the breakdown of acetyl units derived from GLUCOSE; FATTY ACIDS; or AMINO ACIDS by means of tricarboxylic acid intermediates. The end products are CARBON DIOXIDE, water, and energy in the form of phosphate bonds. Krebs Cycle,Tricarboxylic Acid Cycle,Citric Acid Cycles,Cycle, Citric Acid,Cycle, Krebs,Cycle, Tricarboxylic Acid,Cycles, Citric Acid,Cycles, Tricarboxylic Acid,Tricarboxylic Acid Cycles
D006321 Heart The hollow, muscular organ that maintains the circulation of the blood. Hearts

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