Phosphocreatine content in single fibers of human muscle after sustained submaximal exercise.
Document identifier: oai:dalea.du.se:2331
Publication year: 1997Relevant Sustainable Development Goals (SDGs):
The SDG label(s) above have been assigned by OSDG.aiAbstract: The effect of sustained submaximal exercise on muscle energetics has been studied on the single-fiber level in human skeletal muscle. Seven subjects cycled to fatigue (mean 77 min) at a work rate corresponding to approximately 75% of maximal O2 uptake. Biopsies were taken from the vastus lateralis muscle at rest, at fatigue, and after 5 min of recovery. Muscle glycogen decreased from 444 +/- 40 (SE) mmol glucosyl units/kg dry wt at rest to 94 +/- 16. Postexercise glycogen was inversely correlated (P < 0.01) to muscle content of inosine monophosphate, a catabolite of ATP. Phosphocreatine (PCr) in mixed-fiber muscle decreased at fatigue to 37% but was restored above the initial value (106.5%, P < 0.025) after 5 min of recovery. The overshoot was localized to type I fibers. The rapid reversal of PCr is in contrast to the slow recovery in contraction force. Pi increased at fatigue but less than that expected from the changes in PCr and other phosphate compounds. Mean PCr at rest was approximately 20% higher in type II than in type I fibers (86.4 +/- 3.6 and 71.6 +/- 1.8 mmol/kg dry wt, respectively, P < 0.05), but at fatigue similar PCr contents were observed in the two fiber types. Reduction in PCr in all fibers at fatigue suggests that all fibers were recruited at the end of exercise. PCr content in single fibers showed a great variability in samples at rest, exercise, and recovery. The variability was more pronounced than for ATP, and the data suggest that it is due to interfiber physiological-biochemical differences. At fatigue ATP was maintained relatively high in all single fibers, but a pronounced depletion of PCr was observed in a large number of fibers, and this may contribute to fatigue through the associated increases in Pi or/and free ADP. It is noteworthy that the increase in calculated free ADP at fatigue was similar to that after high-intensity exercise.
Authors
Kent Sahlin
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Karin Söderlund
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Michail Tonkonogi
Högskolan Dalarna; Medicinsk vetenskap
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Koji Hirakoba
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identifier: oai:dalea.du.se:2331
datestamp: 2021-04-15T13:11:48Z
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lang: eng
title: Phosphocreatine content in single fibers of human muscle after sustained submaximal exercise.
abstract: The effect of sustained submaximal exercise on muscle energetics has been studied on the single-fiber level in human skeletal muscle. Seven subjects cycled to fatigue (mean 77 min) at a work rate corresponding to approximately 75% of maximal O2 uptake. Biopsies were taken from the vastus lateralis muscle at rest at fatigue and after 5 min of recovery. Muscle glycogen decreased from 444 +/- 40 (SE) mmol glucosyl units/kg dry wt at rest to 94 +/- 16. Postexercise glycogen was inversely correlated (P < 0.01) to muscle content of inosine monophosphate a catabolite of ATP. Phosphocreatine (PCr) in mixed-fiber muscle decreased at fatigue to 37% but was restored above the initial value (106.5% P < 0.025) after 5 min of recovery. The overshoot was localized to type I fibers. The rapid reversal of PCr is in contrast to the slow recovery in contraction force. Pi increased at fatigue but less than that expected from the changes in PCr and other phosphate compounds. Mean PCr at rest was approximately 20% higher in type II than in type I fibers (86.4 +/- 3.6 and 71.6 +/- 1.8 mmol/kg dry wt respectively P < 0.05) but at fatigue similar PCr contents were observed in the two fiber types. Reduction in PCr in all fibers at fatigue suggests that all fibers were recruited at the end of exercise. PCr content in single fibers showed a great variability in samples at rest exercise and recovery. The variability was more pronounced than for ATP and the data suggest that it is due to interfiber physiological-biochemical differences. At fatigue ATP was maintained relatively high in all single fibers but a pronounced depletion of PCr was observed in a large number of fibers and this may contribute to fatigue through the associated increases in Pi or/and free ADP. It is noteworthy that the increase in calculated free ADP at fatigue was similar to that after high-intensity exercise.
language:
languageTerm: eng
genre:
publication/journal-article
ref
note:
Published
4
name:
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type: personal
namePart:
Sahlin
Kent
role:
roleTerm: aut
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type: personal
namePart:
Söderlund
Karin
role:
roleTerm: aut
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type: personal
authority: du
namePart:
Tonkonogi
Michail
role:
roleTerm: aut
affiliation:
Högskolan Dalarna
Medicinsk vetenskap
nameIdentifier:
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0000-0003-1619-9758
@attributes:
type: personal
namePart:
Hirakoba
Koji
role:
roleTerm: aut
originInfo:
dateIssued: 1997
relatedItem:
@attributes:
type: host
titleInfo:
title: American Journal of Physiology. Heart and Circulatory Physiology
identifier:
0363-6135
1522-1539
part:
detail:
@attributes:
type: volume
number: 273
extent:
start: C172
end: C178
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form: print
typeOfResource: text