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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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Pourfathi M, Xin Y, Kadlecek SJ, Cereda MF, Profka H, Hamedani H, Siddiqui SM, Ruppert K, Drachman NA, Rajaei JN, Rizi RR. In vivo imaging of the progression of acute lung injury using hyperpolarized [1- 13 C] pyruvate. Magn Reson Med 2017; 78:2106-2115. [PMID: 28074497 DOI: 10.1002/mrm.26604] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/29/2016] [Accepted: 12/20/2016] [Indexed: 12/19/2022]
Abstract
PURPOSE To investigate pulmonary metabolic alterations during progression of acute lung injury. METHODS Using hyperpolarized [1-13 C] pyruvate imaging, we measured pulmonary lactate and pyruvate in 15 ventilated rats 1, 2, and 4 h after initiation of mechanical ventilation. Lung compliance was used as a marker for injury progression. 5 untreated rats were used as controls; 5 rats (injured-1) received 1 ml/kg and another 5 rats (injured-2) received 2 ml/kg hydrochloric acid (pH 1.25) in the trachea at 70 min. RESULTS The mean lactate-to-pyruvate ratio of the injured-1 cohort was 0.15 ± 0.02 and 0.15 ± 0.03 at baseline and 1 h after the injury, and significantly increased from the baseline value 3 h after the injury to 0.23 ± 0.02 (P = 0.002). The mean lactate-to-pyruvate ratio of the injured-2 cohort decreased from 0.14 ± 0.03 at baseline to 0.08 ± 0.02 1 h after the injury and further decreased to 0.07 ± 0.02 (P = 0.08) 3 h after injury. No significant change was observed in the control group. Compliance in both injured groups decreased significantly after the injury (P < 0.01). CONCLUSIONS Our findings suggest that in severe cases of lung injury, edema and hyperperfusion in the injured lung tissue may complicate interpretation of the pulmonary lactate-to-pyruvate ratio as a marker of inflammation. However, combining the lactate-to-pyruvate ratio with pulmonary compliance provides more insight into the progression of the injury and its severity. Magn Reson Med 78:2106-2115, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Mehrdad Pourfathi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stephen J Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Maurizio F Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sarmad M Siddiqui
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kai Ruppert
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nicholas A Drachman
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jennia N Rajaei
- School of Medicine, Stanford University, Stanford, California, USA
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Smith H, Yates EA, Cole JA, Parsons NJ. Lactate stimulation of gonococcal metabolism in media containing glucose: mechanism, impact on pathogenicity, and wider implications for other pathogens. Infect Immun 2001; 69:6565-72. [PMID: 11598023 PMCID: PMC100028 DOI: 10.1128/iai.69.11.6565-6572.2001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- H Smith
- Medical School, University of Birmingham, Birmingham B15 2TT, United Kingdom
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