Exercise training increases skeletal muscle mitochondrial volume density by enlargement of existing mitochondria and not de novo biogenesis
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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Exercise training increases skeletal muscle mitochondrial volume density by enlargement of existing mitochondria and not de novo biogenesis. / Lundby, Anne-Kristine Meinild; Jacobs, R A; Gehrig, S; de Leur, J; Hauser, M; Bonne, Thomas Christian; Flück, Daniela; Dandanell, Sune; Kirk, N; Kaech, A; Ziegler, U; Larsen, Steen; Lundby, Carsten.
I: Acta Physiologica (Print), Bind 222, Nr. 1, e12905, 2018.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Exercise training increases skeletal muscle mitochondrial volume density by enlargement of existing mitochondria and not de novo biogenesis
AU - Lundby, Anne-Kristine Meinild
AU - Jacobs, R A
AU - Gehrig, S
AU - de Leur, J
AU - Hauser, M
AU - Bonne, Thomas Christian
AU - Flück, Daniela
AU - Dandanell, Sune
AU - Kirk, N
AU - Kaech, A
AU - Ziegler, U
AU - Larsen, Steen
AU - Lundby, Carsten
PY - 2018
Y1 - 2018
N2 - Aims: (i) To determine whether exercise-induced increases in muscle mitochondrial volume density (MitoVD) are related to enlargement of existing mitochondria or de novo biogenesis and (ii) to establish whether measures of mitochondrial-specific enzymatic activities are valid biomarkers for exercise-induced increases in MitoVD. Method: Skeletal muscle samples were collected from 21 healthy males prior to and following 6 weeks of endurance training. Transmission electron microscopy was used for the estimation of mitochondrial densities and profiles. Biochemical assays, western blotting and high-resolution respirometry were applied to detect changes in specific mitochondrial functions. Result: MitoVD increased with 55 ± 9% (P < 0.001), whereas the number of mitochondrial profiles per area of skeletal muscle remained unchanged following training. Citrate synthase activity (CS) increased (44 ± 12%, P < 0.001); however, there were no functional changes in oxidative phosphorylation capacity (OXPHOS, CI+IIP) or cytochrome c oxidase (COX) activity. Correlations were found between MitoVD and CS (P = 0.01; r = 0.58), OXPHOS, CI+CIIP (P = 0.01; R = 0.58) and COX (P = 0.02; R = 0.52) before training; after training, a correlation was found between MitoVD and CS activity only (P = 0.04; R = 0.49). Intrinsic respiratory capacities decreased (P < 0.05) with training when respiration was normalized to MitoVD. This was not the case when normalized to CS activity although the percentage change was comparable. Conclusions: MitoVD was increased by inducing mitochondrial enlargement rather than de novo biogenesis. CS activity may be appropriate to track training-induced changes in MitoVD.
AB - Aims: (i) To determine whether exercise-induced increases in muscle mitochondrial volume density (MitoVD) are related to enlargement of existing mitochondria or de novo biogenesis and (ii) to establish whether measures of mitochondrial-specific enzymatic activities are valid biomarkers for exercise-induced increases in MitoVD. Method: Skeletal muscle samples were collected from 21 healthy males prior to and following 6 weeks of endurance training. Transmission electron microscopy was used for the estimation of mitochondrial densities and profiles. Biochemical assays, western blotting and high-resolution respirometry were applied to detect changes in specific mitochondrial functions. Result: MitoVD increased with 55 ± 9% (P < 0.001), whereas the number of mitochondrial profiles per area of skeletal muscle remained unchanged following training. Citrate synthase activity (CS) increased (44 ± 12%, P < 0.001); however, there were no functional changes in oxidative phosphorylation capacity (OXPHOS, CI+IIP) or cytochrome c oxidase (COX) activity. Correlations were found between MitoVD and CS (P = 0.01; r = 0.58), OXPHOS, CI+CIIP (P = 0.01; R = 0.58) and COX (P = 0.02; R = 0.52) before training; after training, a correlation was found between MitoVD and CS activity only (P = 0.04; R = 0.49). Intrinsic respiratory capacities decreased (P < 0.05) with training when respiration was normalized to MitoVD. This was not the case when normalized to CS activity although the percentage change was comparable. Conclusions: MitoVD was increased by inducing mitochondrial enlargement rather than de novo biogenesis. CS activity may be appropriate to track training-induced changes in MitoVD.
KW - Adaptations
KW - Mitochondria
KW - Muscle
KW - Training
KW - Volume density
U2 - 10.1111/apha.12905
DO - 10.1111/apha.12905
M3 - Journal article
C2 - 28580772
AN - SCOPUS:85021792645
VL - 222
JO - Acta Physiologica
JF - Acta Physiologica
SN - 1748-1708
IS - 1
M1 - e12905
ER -
ID: 210200607