The intracellular to extracellular proton gradient following maximal whole body exercise and its implication for anaerobic energy production

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Stefanos Voiantis, Niels H. Secher, Bjørn Quistorff

Maximal exercise elicits systemic acidosis where venous pH can drop to 6.74 and here we assessed how much lower the intracellular value (pHi) might be. The wrist flexor muscles are intensively involved in rowing and 31P-magnetic resonance spectroscopy allows for calculation of forearm pHi and energy metabolites at high time resolution. Arm venous blood was collected in seven competitive rowers (4 males; 72 ± 5 kg; mean ± SD) at rest and immediately after a “2,000 m” maximal rowing ergometer effort when hemoglobin O2 saturation decreased from 51 ± 4 to 29 ± 9% and lactate rose from 1.0 ± 0.1 to 16.8 ± 3.6 mM. Venous pH and pHi decreased from 7.43 ± 0.01 to 6.90 ± 0.01 and from 7.05 ± 0.02 to 6.32 ± 0.19 (P < 0.05), respectively, while the ratio of inorganic phosphate to phosphocreatine increased from 0.12 ± 0.03 to 1.50 ± 0.49 (P < 0.05). The implication of the recorded intravascular and intracellular acidosis and the decrease in PCr is that the anaerobic contribution to energy metabolism during maximal rowing corresponds to 4.47 ± 1.8 L O2, a value similar to that defined as the “accumulated oxygen deficit”. In conclusion, during maximal rowing the intracellular acidosis, expressed as proton concentration, surpasses ~4-fold the intravascular acidosis, while the resting gradient is ~2.
Original languageEnglish
JournalEuropean Journal of Applied Physiology
Volume109
Issue number6
Pages (from-to)1171-1177
Number of pages7
ISSN1439-6319
DOIs
Publication statusPublished - Aug 2010

ID: 33908395