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Zhang X, Dash RK, Clough AV, Xie D, Jacobs ER, Audi SH. Integrated Computational Model of Lung Tissue Bioenergetics. Front Physiol 2019; 10:191. [PMID: 30906264 PMCID: PMC6418344 DOI: 10.3389/fphys.2019.00191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 02/15/2019] [Indexed: 11/29/2022] Open
Abstract
Altered lung tissue bioenergetics plays a key role in the pathogenesis of lung diseases. A wealth of information exists regarding the bioenergetic processes in mitochondria isolated from rat lungs, cultured pulmonary endothelial cells, and intact rat lungs under physiological and pathophysiological conditions. However, the interdependence of those processes makes it difficult to quantify the impact of a change in a single or multiple process(es) on overall lung tissue bioenergetics. Integrated computational modeling provides a mechanistic and quantitative framework for the bioenergetic data at different levels of biological organization. The objective of this study was to develop and validate an integrated computational model of lung bioenergetics using existing experimental data from isolated perfused rat lungs. The model expands our recently developed computational model of the bioenergetics of mitochondria isolated from rat lungs by accounting for glucose uptake and phosphorylation, glycolysis, and the pentose phosphate pathway. For the mitochondrial region of the model, values of kinetic parameters were fixed at those estimated in our recent model of the bioenergetics of mitochondria isolated from rat lungs. For the cytosolic region of the model, intrinsic parameters such as apparent Michaelis constants were determined based on previously published enzyme kinetics data, whereas extrinsic parameters such as maximal reaction and transport velocities were estimated by fitting the model solution to published data from isolated rat lungs. The model was then validated by assessing its ability to predict existing experimental data not used for parameter estimation, including relationships between lung nucleotides content, lung lactate production rate, and lung energy charge under different experimental conditions. In addition, the model was used to gain novel insights on how lung tissue glycolytic rate is regulated by exogenous substrates such as glucose and lactate, and assess differences in the bioenergetics of mitochondria isolated from lung tissue and those of mitochondria in intact lungs. To the best of our knowledge, this is the first model of lung tissue bioenergetics. The model provides a mechanistic and quantitative framework for integrating available lung tissue bioenergetics data, and for testing novel hypotheses regarding the role of different cytosolic and mitochondrial processes in lung tissue bioenergetics.
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Affiliation(s)
- Xiao Zhang
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United States
| | - Ranjan K Dash
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United States.,Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, United States.,Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Anne V Clough
- Zablocki V. A. Medical Center, Milwaukee, WI, United States.,Department of Mathematics, Statistics, and Computer Science, Marquette University, Milwaukee, WI, United States
| | - Dexuan Xie
- Department of Mathematical Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Elizabeth R Jacobs
- Zablocki V. A. Medical Center, Milwaukee, WI, United States.,Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Said H Audi
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI, United States.,Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, United States.,Zablocki V. A. Medical Center, Milwaukee, WI, United States.,Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI, United States
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Skalecki K, Rakus D, Wiśniewski JR, Kolodziej J, Dzugaj A. cDNA sequence and kinetic properties of human lung fructose(1, 6)bisphosphatase. Arch Biochem Biophys 1999; 365:1-9. [PMID: 10222032 DOI: 10.1006/abbi.1999.1120] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A cDNA encoding fructose(1,6)bisphosphatase was isolated from total human lung RNA. The cDNA contained an open reading frame encoding 337 amino acids. The determined nucleotide sequence of the lung cDNA was significantly different from muscle cDNA and slightly differed from human liver cDNA in a single mutation (Gly-336 for Ala-336) and a T for C substitution in position 648. The human lung fructose(1, 6)bisphosphatase [Fru(1,6)Pase] was isolated and its kinetic parameters were compared with liver and muscle isoenzymes. Values of kcat for the lung Fru(1,6)Pase were lower than for the liver and muscle enzyme. Like the liver isoenzyme, lung Fru(1,6)Pase is significantly less inhibited by AMP than the muscle enzyme. The values of I0.5 were 9.5, 9.8, and 0.3 microM for the liver, lung, and muscle enzyme, respectively. The lung enzyme was slightly more sensitive to fructose(2,6)bisphosphate [Fru(2,6)P2] inhibition than the liver enzyme. Ki was 75 microM for the lung and 96 microM for the liver enzyme. The synergistic effect of AMP and Fru(2,6)P2 on the lung and liver Fru(1,6)Pase was also observed. In the presence of AMP the corresponding values of Ki for Fru(2,6)P2 were 16 microM for the lung and 10 microM for the liver enzyme.
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Affiliation(s)
- K Skalecki
- Institute of Zoology, University of Wroclaw, Cybulskiego 30, Wroclcaw, 50-205, Poland
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Saumon G, Martet G. Effect of metabolic inhibitors on Na+ transport in isolated perfused rat lungs. Am J Respir Cell Mol Biol 1993; 9:157-65. [PMID: 7687851 DOI: 10.1165/ajrcmb/9.2.157] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Alveolar fluid absorption is a process driven by transepithelial alveolar Na+ transport. Since lungs produce significant amounts of lactate under anaerobic but also under aerobic conditions, glycolysis may conceivably contribute to producing the energy needed for transepithelial Na+ transport and fluid absorption. The effects of inhibition of oxidative phosphorylation or glycolysis on alveolar Na+ transport, fluid absorption, and preservation of alveolar epithelial barrier properties were examined using isolated, fluid-filled rat lungs. Basal lung lactate production was 65 +/- 1.0 mumol/h/g dry wt in the presence of 10 mmol/liter glucose. When oxidative phosphorylation was inhibited with rotenone, cyanide, or the uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP), lung lactate production increased 5- to 7-fold within 30 min (P < 0.001). No significant decrease in alveolar Na+ transport was observed over 1 h, whereas a 3-fold increase in passive epithelial permeability was observed. With rotenone and CCCP, but not cyanide, fluid absorption from airspaces was decreased but never abolished. Inhibition of aerobic glycolysis with iodoacetate did not significantly affect alveolar Na+ transport or fluid absorption. In the presence of isoproterenol or dibutyryl cyclic adenosine monophosphate (cAMP) + isobutylmethylxanthine, which have previously been shown to stimulate alveolar Na+ transport, lung lactate production increased 2-fold (P < 0.001). Inhibition of glycolysis depressed stimulated alveolar Na+ and fluid transports (P < 0.001). Inhibition of ion transport by ouabain or amiloride decreased lung lactate production (P < 0.001) under stimulated but not under unstimulated conditions. These observations suggest that glycolysis does not significantly contribute to energy provision for alveolar epithelial Na+ transport in lungs under basal, aerobic conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- G Saumon
- INSERM U82, Faculté Xavier Bichat, Paris, France
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van Erp HE, Rijksen G, van der Saag PT, Staal GE. Phosphofructokinase and pyruvate kinase in mouse embryonal carcinoma P19 cells in relation to growth and differentiation. Differentiation 1990; 45:199-205. [PMID: 2151036 DOI: 10.1111/j.1432-0436.1990.tb00474.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Two key enzymes of glycolysis, phosphofructokinase and pyruvate kinase, were studied in embryonal carcinoma cells (P19 EC cells) and three differentiated derivatives in relation to growth rate and differentiation state. The growth rates of P19 EC cells and its differentiated derivatives are positively correlated with both the specific activity of phosphofructokinase and the expression of the L-subunit of this enzyme. The specific activity of pyruvate kinase and its isozyme composition is not correlated with growth rate but seems to be correlated with the differentiation state of these cells. The decrease in specific activity of pyruvate kinase during differentiation of P19 EC cells induced by retinoic acid or dimethylsulfoxide preceded the shift from K- to M-type pyruvate kinase. In contrast to aggregates that were treated with dimethylsulfoxide, the specific activity of pyruvate kinase was reduced after aggregation in the presence of retinoic acid. Only after plating dimethylsulfoxide-treated aggregates again in the presence of dimethylsulfoxide, was a decrease in specific activity obtained. Both retinoic acid and dimethylsulfoxide are able to induce a K- to -M shift of pyruvate kinase.
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Affiliation(s)
- H E van Erp
- Department of Hematology, University Hospital Utrecht, The Netherlands
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