Bicarbonate infusion and pH clamp moderately reduce hyperventilation during ramp exercise in humans.
To test the hypothesis that the decrease in plasma pH contributes to the hyperventilation observed in humans in response to exercise at high workloads, five healthy male subjects performed a ramp exercise [maximal workload: 352 W (SD 35)] in a control situation and when arterialized plasma pH was maintained at the resting level (pH clamp) by intravenous infusion of sodium bicarbonate [129 mmol (SD 23), beginning at 59% maximal workload (SD 5)]. Bicarbonate infusion did not modify O(2) consumption (Vo(2)) but significantly (P < 0.05) increased arterial Pco(2), plasma bicarbonate concentration, and respiratory exchange ratio (P < 0.05). At the three highest workloads, pulmonary ventilation (Ve) and Ve/Vo(2) were approximately 5-10% lower (P < 0.05) when bicarbonate was infused than in the control situation, and hyperventilation was reduced by 15-30%. These data suggest that the decrease in plasma pH is one of the factors that contribute to the hyperventilation observed at high workloads.
Péronnet
François
F
Département de Kinésiologie, Université de Montréal, CP 6128, Centre Ville, Montréal, QC, Canada H3C3J7. francois.peronnet@umontreal.ca
Meyer
Tim
T
Aguilaniu
Bernard
B
Juneau
Carl-Etienne
CE
Faude
Oliver
O
Kindermann
Wilfried
W
D000136:Acid-Base Equilibrium / Q000502:physiology; D000328:Adult; D001639:Bicarbonates / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D002245:Carbon Dioxide / Q000097:blood; D015444:Exercise / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006985:Hyperventilation / Q000503:physiopathology*; D007262:Infusions, Intravenous; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D012123:Pulmonary Ventilation / Q000187:drug effects / Q000502:physiology; D012146:Rest / Q000502:physiology
D001639:Bicarbonates; D002245:Carbon Dioxide