TY - JOUR
T1 - The intracellular to extracellular proton gradient following maximal whole body exercise and its implication for anaerobic energy production
AU - Voiantis, Stefanos
AU - Secher, Niels H.
AU - Quistorff, Bjørn
PY - 2010/8
Y1 - 2010/8
N2 - Maximal exercise elicits systemic acidosis where venous pH can drop to 6.74 and here we assessed how much lower the intracellular value (pH i) might be. The wrist flexor muscles are intensively involved in rowing and 31P-magnetic resonance spectroscopy allows for calculation of forearm pH i 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 O 2 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 pH i 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 O 2, 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.
AB - Maximal exercise elicits systemic acidosis where venous pH can drop to 6.74 and here we assessed how much lower the intracellular value (pH i) might be. The wrist flexor muscles are intensively involved in rowing and 31P-magnetic resonance spectroscopy allows for calculation of forearm pH i 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 O 2 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 pH i 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 O 2, 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.
KW - Faculty of Health and Medical Sciences
U2 - 10.1007/s00421-010-1451-5
DO - 10.1007/s00421-010-1451-5
M3 - Journal article
C2 - 20379830
SN - 1439-6319
VL - 109
SP - 1171
EP - 1177
JO - European Journal of Applied Physiology
JF - European Journal of Applied Physiology
IS - 6
ER -