Hyperpolarized (13)C MR measurements have the potential to display non-linear kinetics. We have developed an approach to describe possible non-first-order kinetics of hyperpolarized [1-(13)C] pyruvate employing a system of differential equations that agrees with the principle of conservation of mass of the hyperpolarized signal. Simultaneous fitting to a second-order model for conversion of [1-...

1. The carboxylation of pyruvate to oxaloacetate by pyruvate carboxylase in guinea-pig liver mitochondria was determined by measuring the amount of (14)C from H(14)CO(3) (-) fixed into organic acids in the presence of pyruvate, ATP, Mg(2+) and P(i). The main products of pyruvate carboxylation were malate, fumarate and citrate. Pyruvate utilization, metabolite formation and incorporation of (14)...

The percentage of total pyruvate dehydrogenase in the active nonphosphorylated form was measured in intact rat liver mitochondria after rapid separation of the mitochondria through silicone oil and extraction with glycerol buffer at 10”. The contents of ATP, ADP, Mg2+, and Ca2+ in the mitochondrial matrix of separated mitochondria were determined in parallel experiments. Mitochondria were incub...

We have presented evidence that stimulation of pyruvate dehydrogenase, (PDH.) kinase activity by pyruvate or by acetyl-CoA is mediated through acetylation of lipoyl moieties (Cate, R. L., and Roche, T. E. (1978) J. Biol. Chem. 253,496-503). In accord with this indirect mechanism for the action of these effecters, we now find that the degree of stimulation of PDH, kinase increases with the level...

Transpulmonary Lactate and Pyruvate Kinetics by Matthew Lawrence Johnson Doctor of Philosophy in Integrative Biology University of California, Berkeley Professor George A. Brooks, Chair Shuttling of intermediary metabolites such as lactate and pyruvate contribute to the dynamic energy needs of tissues. Tracer kinetic studies offer a powerful method to measure the metabolism of substrates like l...

Whole cells and cell-free extracts of Clostridium thermosaccharolyticum 3814 grown in media containing 0.5% glucose or 0.6% pyruvate were evaluated for their metabolic activities toward these compounds. Glucose-grown cells rapidly fermented glucose with the production of gases (CO(2) and H(2)), acids, and alcohol, but they did not ferment pyruvate well. Pyruvate-grown cells, on the other hand, ...

1. The effect of phenylalanine and phenylpyruvate on the metabolism of pyruvate by isolated mitochondria from rat brain was investigated. 2. Phenylpyruvate inhibited the fixation of H(14)CO(3) (-) in the presence of pyruvate by intact rat brain mitochondria, whereas phenylalanine and other metabolites of this amino acid had no inhibitory effect on this process. 3. Pyruvate carboxylase activity ...

Continuous 14C 0 2 Evolution, Glycolytic Compartment, Pyruvate Metabolism, Synchronous, Yeast The different metabolic behaviour of endogenously produced [1-14C] pyruvate derived from [3,4-14C]glucose and of exogenously added [1-14C]pyruvate were studied with synchronous yeast cell populations, under conditions which differentially influenced the activities of pyruvate decarboxylase in the cytop...

Hormonal control of the initial step in hepatic gluconeogenesis from pyruvate was examined following acute administration of epinephrine, glucagon, or cortisol to adult rats. After hormonal treatment of the animals, the mitochondria were isolated for the study of pyruvate metabolism. When pyruvate and bicarbonate were the only substrates provided, mitochondrial fixation of carbon dioxide and pr...