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Intracellular pH and phosphate: are they limiting factors during exercise of high intensity?

Zange, Jochen und Beisteiner, Mareike und Müller, Klaus und Maassen, Norbert (2007) Intracellular pH and phosphate: are they limiting factors during exercise of high intensity? In: Acta Physiologica, S653, Seite 33. Blackwell Publishing. 86. Jahrestagung der Deutschen Physiologischen Gesellschaft, 2007-03-25 - 2007-03-28, Hannover. ISSN 1748-1776

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Kurzfassung

Intracellular acidosis caused by lactic acid formation and the accumulation of inorganic phosphate (Pi) by phosphocreatine (PCr) breakdown were regarded to be major factors in the process of muscle fatigue. However, recent studies on skinned and intact isolated mammalian muscle fibres at physiological temperatures have only shown minor effects of physiologically low pH values on contractility. Physiologically high concentrations of phosphate seem to reduce force and shortening velocity by a direct inhibition of acto-myosin ATPase and by a reduction in Ca-release from SR. Recent in-vivo studies using 31P MRS on human skeletal muscle seem to support these findings. During intense dynamic interval exercise, contraction velocity of the calf muscle significantly fell by about 30% within each interval while pH was increasing by about 0.3 units in average due to PCr consumption and an increase in Pi. Starting from 2nd contraction interval velocity was also initially reduced by about 20%, which corresponds with an incomplete recovery of PCr and Pi. However, also a 10% reduction in initial EMG amplitude was observed. The relative indecency of muscle fatigue from acidosis and the potential role of Pi accumulation in fatigue can also be shown in patients with myo-phosphorylase deficiency. These patients show distinct signs of fatigue after only moderate muscle load, which causes an alkalinisation and a steep PCr breakdown and Pi accumulation.

Dokumentart:Konferenzbeitrag (Vortrag)
Titel:Intracellular pH and phosphate: are they limiting factors during exercise of high intensity?
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Zange, JochenNICHT SPEZIFIZIERT
Beisteiner, MareikeNICHT SPEZIFIZIERT
Müller, KlausNICHT SPEZIFIZIERT
Maassen, NorbertMedizinische Hochschule Hannover
Datum:März 2007
Erschienen in:Acta Physiologica
Band:S653
Seitenbereich:Seite 33
Verlag:Blackwell Publishing
ISSN:1748-1776
Status:veröffentlicht
Stichwörter:muscle fatigue, peripheral factors of fatigue, 31P-magnetic resonance spectroscopy, electromyography, exercise
Veranstaltungstitel:86. Jahrestagung der Deutschen Physiologischen Gesellschaft
Veranstaltungsort:Hannover
Veranstaltungsart:nationale Konferenz
Veranstaltungsdatum:2007-03-25 - 2007-03-28
Veranstalter :Medizinische Hochschule Hannover
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W FR - Forschung unter Weltraumbedingungen (alt)
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W FR - Forschung unter Weltraumbedingungen
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Beschleunigungsinduzierte Effekte (alt)
Standort: Köln-Porz
Institute & Einrichtungen:Institut für Luft- und Raumfahrtmedizin > Weltraumphysiologie
Hinterlegt von: Dr.rer.nat. Jochen Zange
Hinterlegt am:08 Mai 2007
Letzte Änderung:27 Apr 2009 13:38

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