Increased concentrations of Pi and lactic acid reduce creatine stimulated respiration in muscle fibres.
Document identifier: oai:dalea.du.se:2316
Keyword: Acidosis; mitochondria; muscle energetics; oxidative phosphorylation; phosphatPublication year: 2002Abstract: We tested the hypothesis that the respiratory function of skeletal muscle mitochondria is impaired by lactic acidosis and elevated concentrations of Pi. The rate of respiration of chemically skinned fiber bundles from rat soleus muscle was measured at [Pi] (brackets denote concentration) and pH values similar to those at rest (3 mM Pi, pH 7.0) and high-intensity exercise (20 mM Pi, pH 6.6). Respiration was measured in the absence of ADP and after sequential additions of 0.1 mM ADP, 20 mM creatine (Cr; VCr), and 4 mM ADP. Respiration at 0.1 mM ADP increased after addition of Cr. However, VCr was 23% lower (P < 0.05) during high-intensity conditions than during resting conditions. VCr was also reduced when Pi or H+ was increased separately (P < 0.05). Respiration in the absence of ADP and after additions of 0.1 mM ADP and 4 mM ADP was not affected by changes in [Pi] or [H+]. The response was similar, irrespective of when acidosis was induced (i.e., quiescent or actively respiring mitochondria). In conclusion, Cr-stimulated respiration is impaired by increases in [H+] and [Pi] corresponding to those in exercising muscle. Although the reduced Cr-stimulated respiration could be compensated for by increased [ADP], this might have implications for intracellular homeostasis.
Authors
Brandon Walsh
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Toomas Tiivel
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Michail Tonkonogi
Högskolan Dalarna; Medicinsk vetenskap
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Kent Sahlin
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identifier: oai:dalea.du.se:2316
datestamp: 2023-02-15T17:03:32Z
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lang: eng
title: Increased concentrations of Pi and lactic acid reduce creatine stimulated respiration in muscle fibres.
abstract: We tested the hypothesis that the respiratory function of skeletal muscle mitochondria is impaired by lactic acidosis and elevated concentrations of Pi. The rate of respiration of chemically skinned fiber bundles from rat soleus muscle was measured at Pi (brackets denote concentration) and pH values similar to those at rest (3 mM Pi pH 7.0) and high-intensity exercise (20 mM Pi pH 6.6). Respiration was measured in the absence of ADP and after sequential additions of 0.1 mM ADP 20 mM creatine (Cr; VCr) and 4 mM ADP. Respiration at 0.1 mM ADP increased after addition of Cr. However VCr was 23% lower (P < 0.05) during high-intensity conditions than during resting conditions. VCr was also reduced when Pi or H+ was increased separately (P < 0.05). Respiration in the absence of ADP and after additions of 0.1 mM ADP and 4 mM ADP was not affected by changes in Pi or H+. The response was similar irrespective of when acidosis was induced (i.e. quiescent or actively respiring mitochondria). In conclusion Cr-stimulated respiration is impaired by increases in H+ and Pi corresponding to those in exercising muscle. Although the reduced Cr-stimulated respiration could be compensated for by increased ADP this might have implications for intracellular homeostasis.
subject:
@attributes:
lang: eng
topic: acidosis; mitochondria; muscle energetics; oxidative phosphorylation; phosphat
language:
languageTerm: eng
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publication/journal-article
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Published
4
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type: personal
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Walsh
Brandon
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type: personal
namePart:
Tiivel
Toomas
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authority: du
namePart:
Tonkonogi
Michail
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affiliation:
Högskolan Dalarna
Medicinsk vetenskap
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0000-0003-1619-9758
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Sahlin
Kent
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originInfo:
dateIssued: 2002
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titleInfo:
title: Journal of applied physiology
identifier:
8750-7587
1522-1601
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type: volume
number: 92
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start: 2273
end: 2276
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