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EMG-normalised kinase activation during exercise is higher in human gastrocnemius compared to soleus muscle.

Jensen TE, Leutert R, Rasmussen ST, Mouatt JR, Christiansen ML, Jensen BR, Richter EA - PLoS ONE (2012)

Bottom Line: No differences were found in protein expression of signalling proteins (AMPK subunits, eEF2, ERK1/2, TBC1D1 and 4), mitochondrial markers (F1 ATPase and COX1) or ROS-handling enzymes (SOD2 and catalase).In conclusion, proteins with muscle-group restricted expression in mice do not show this pattern in human lower extremity muscle groups.This may be due to the combined subtle effects of a higher type I muscle fiber content and higher training status in soleus compared to gastrocnemius muscle.

View Article: PubMed Central - PubMed

Affiliation: Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark. TEJensen@ifi.ku.dk

ABSTRACT
In mice, certain proteins show a highly confined expression in specific muscle groups. Also, resting and exercise/contraction-induced phosphorylation responses are higher in rat skeletal muscle with low mitochondrial content compared to muscles with high mitochondrial content, possibly related to differential reactive oxygen species (ROS)-scavenging ability or resting glycogen content. To evaluate these parameters in humans, biopsies from soleus, gastrocnemius and vastus lateralis muscles were taken before and after a 45 min inclined (15%) walking exercise bout at 69% VO2(max) aimed at simultaneously activating soleus and gastrocnemius in a comparable dynamic work-pattern. Hexokinase II and GLUT4 were 46-59% and 26-38% higher (p<0.05) in soleus compared to the two other muscles. The type I muscle fiber percentage was highest in soleus and lowest in vastus lateralis. No differences were found in protein expression of signalling proteins (AMPK subunits, eEF2, ERK1/2, TBC1D1 and 4), mitochondrial markers (F1 ATPase and COX1) or ROS-handling enzymes (SOD2 and catalase). Gastrocnemius was less active than soleus measured as EMG signal and glycogen use yet gastrocnemius displayed larger increases than soleus in phosphorylation of AMPK Thr172, eEF2 Thr56 and ERK 1/2 Thr202/Tyr204 when normalised to the mean relative EMG-signal. In conclusion, proteins with muscle-group restricted expression in mice do not show this pattern in human lower extremity muscle groups. Nonetheless the phosphorylation-response is greater for a number of kinase signalling pathways in human gastrocnemius than soleus at a given activation-intensity. This may be due to the combined subtle effects of a higher type I muscle fiber content and higher training status in soleus compared to gastrocnemius muscle.

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Overview of experimental protocol for pre-test day and experimental days 1 and 2.
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pone-0031054-g001: Overview of experimental protocol for pre-test day and experimental days 1 and 2.

Mentions: A schematic overview of the experimental protocol is shown in figure 1. All subjects completed a 15% inclined 45 min uphill walking bout covering a mean distance of 4770 m and corresponding to a 715 m elevation. This elicited a mean oxygen uptake of 69.1±1.6 %VO2 max and changes in various blood metabolites and hormones typical of whole-body exercise at this intensity including increased lactate and catecholamines and lower insulin (table 1).


EMG-normalised kinase activation during exercise is higher in human gastrocnemius compared to soleus muscle.

Jensen TE, Leutert R, Rasmussen ST, Mouatt JR, Christiansen ML, Jensen BR, Richter EA - PLoS ONE (2012)

Overview of experimental protocol for pre-test day and experimental days 1 and 2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3275615&req=5

pone-0031054-g001: Overview of experimental protocol for pre-test day and experimental days 1 and 2.
Mentions: A schematic overview of the experimental protocol is shown in figure 1. All subjects completed a 15% inclined 45 min uphill walking bout covering a mean distance of 4770 m and corresponding to a 715 m elevation. This elicited a mean oxygen uptake of 69.1±1.6 %VO2 max and changes in various blood metabolites and hormones typical of whole-body exercise at this intensity including increased lactate and catecholamines and lower insulin (table 1).

Bottom Line: No differences were found in protein expression of signalling proteins (AMPK subunits, eEF2, ERK1/2, TBC1D1 and 4), mitochondrial markers (F1 ATPase and COX1) or ROS-handling enzymes (SOD2 and catalase).In conclusion, proteins with muscle-group restricted expression in mice do not show this pattern in human lower extremity muscle groups.This may be due to the combined subtle effects of a higher type I muscle fiber content and higher training status in soleus compared to gastrocnemius muscle.

View Article: PubMed Central - PubMed

Affiliation: Molecular Physiology Group, Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark. TEJensen@ifi.ku.dk

ABSTRACT
In mice, certain proteins show a highly confined expression in specific muscle groups. Also, resting and exercise/contraction-induced phosphorylation responses are higher in rat skeletal muscle with low mitochondrial content compared to muscles with high mitochondrial content, possibly related to differential reactive oxygen species (ROS)-scavenging ability or resting glycogen content. To evaluate these parameters in humans, biopsies from soleus, gastrocnemius and vastus lateralis muscles were taken before and after a 45 min inclined (15%) walking exercise bout at 69% VO2(max) aimed at simultaneously activating soleus and gastrocnemius in a comparable dynamic work-pattern. Hexokinase II and GLUT4 were 46-59% and 26-38% higher (p<0.05) in soleus compared to the two other muscles. The type I muscle fiber percentage was highest in soleus and lowest in vastus lateralis. No differences were found in protein expression of signalling proteins (AMPK subunits, eEF2, ERK1/2, TBC1D1 and 4), mitochondrial markers (F1 ATPase and COX1) or ROS-handling enzymes (SOD2 and catalase). Gastrocnemius was less active than soleus measured as EMG signal and glycogen use yet gastrocnemius displayed larger increases than soleus in phosphorylation of AMPK Thr172, eEF2 Thr56 and ERK 1/2 Thr202/Tyr204 when normalised to the mean relative EMG-signal. In conclusion, proteins with muscle-group restricted expression in mice do not show this pattern in human lower extremity muscle groups. Nonetheless the phosphorylation-response is greater for a number of kinase signalling pathways in human gastrocnemius than soleus at a given activation-intensity. This may be due to the combined subtle effects of a higher type I muscle fiber content and higher training status in soleus compared to gastrocnemius muscle.

Show MeSH
Related in: MedlinePlus