Alessandra Ferri1,2, Alice Panariti2, Giuseppe Miserocchi2, Marcella Rocchetti3, Gaia Buoli Comani2, Ilaria Rivolta4, David J Bishop5,6. 1. Institute for Health and Sport, Victoria University, Melbourne, Australia. 2. School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy. 3. Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy. 4. School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy. ilaria.rivolta@unimib.it. 5. Institute for Health and Sport, Victoria University, Melbourne, Australia. david.bishop@vu.edu.au. 6. School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia. david.bishop@vu.edu.au.
Abstract
PURPOSE: Exposure to hypoxia has been suggested to activate multiple adaptive pathways so that muscles are better able to maintain cellular energy homeostasis. However, there is limited research regarding the tissue specificity of this response. The aim of this study was to investigate the influence of tissue specificity on mitochondrial adaptations of rat skeletal and heart muscles after 4 weeks of normobaric hypoxia (FiO2: 0.10). METHODS: Twenty male Wistar rats were randomly assigned to either normobaric hypoxia or normoxia. Mitochondrial respiration was determined in permeabilised muscle fibres from left and right ventricles, soleus and extensorum digitorum longus (EDL). Citrate synthase activity and the relative abundance of proteins associated with mitochondrial biogenesis were also analysed. RESULTS: After hypoxia exposure, only the soleus and left ventricle (both predominantly oxidative) presented a greater maximal mass-specific respiration (+48 and +25%, p < 0.05) and mitochondrial-specific respiration (+75 and +28%, p < 0.05). Citrate synthase activity was higher in the EDL (0.63 ± 0.08 vs 0.41 ± 0.10 µmol min- 1 µg- 1) and lower in the soleus (0.65 ± 0.17 vs 0.87 ± 0.20 µmol min- 1 µg- 1) in hypoxia with respect to normoxia. There was a lower relative protein abundance of PGC-1α (-25%, p < 0.05) in the right ventricle and a higher relative protein abundance of PGC-1β (+43%, p < 0.05) in the left ventricle of rats exposed to hypoxia, with few differences for protein abundance in the other muscles. CONCLUSION: Our results show a muscle-specific response to 4 weeks of normobaric hypoxia. Depending on fibre type, and the presence of ventricular hypertrophy, muscles respond differently to the same degree of environmental hypoxia.
PURPOSE: Exposure to hypoxia has been suggested to activate multiple adaptive pathways so that muscles are better able to maintain cellular energy homeostasis. However, there is limited research regarding the tissue specificity of this response. The aim of this study was to investigate the influence of tissue specificity on mitochondrial adaptations of rat skeletal and heart muscles after 4 weeks of normobaric hypoxia (FiO2: 0.10). METHODS: Twenty male Wistar rats were randomly assigned to either normobaric hypoxia or normoxia. Mitochondrial respiration was determined in permeabilised muscle fibres from left and right ventricles, soleus and extensorum digitorum longus (EDL). Citrate synthase activity and the relative abundance of proteins associated with mitochondrial biogenesis were also analysed. RESULTS: After hypoxia exposure, only the soleus and left ventricle (both predominantly oxidative) presented a greater maximal mass-specific respiration (+48 and +25%, p < 0.05) and mitochondrial-specific respiration (+75 and +28%, p < 0.05). Citrate synthase activity was higher in the EDL (0.63 ± 0.08 vs 0.41 ± 0.10 µmol min- 1 µg- 1) and lower in the soleus (0.65 ± 0.17 vs 0.87 ± 0.20 µmol min- 1 µg- 1) in hypoxia with respect to normoxia. There was a lower relative protein abundance of PGC-1α (-25%, p < 0.05) in the right ventricle and a higher relative protein abundance of PGC-1β (+43%, p < 0.05) in the left ventricle of rats exposed to hypoxia, with few differences for protein abundance in the other muscles. CONCLUSION: Our results show a muscle-specific response to 4 weeks of normobaric hypoxia. Depending on fibre type, and the presence of ventricular hypertrophy, muscles respond differently to the same degree of environmental hypoxia.
Authors: Cesare Granata; Rodrigo S F Oliveira; Jonathan P Little; Kathrin Renner; David J Bishop Journal: FASEB J Date: 2015-11-16 Impact factor: 5.191
Authors: Glenn C Rowe; Ian S Patten; Zsuzsanna K Zsengeller; Riyad El-Khoury; Mitsuharu Okutsu; Sophia Bampoh; Nicole Koulisis; Caitlin Farrell; Michael F Hirshman; Zhen Yan; Laurie J Goodyear; Pierre Rustin; Zolt Arany Journal: Cell Rep Date: 2013-05-23 Impact factor: 9.423