48405
document
Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise . Exercise lowers the cerebral metabolic ratio of O2 to carbohydrate ( glucose+1/2 lactate ) and metabolic acidosis appears to promote cerebral lactate uptake . However , the influence of pH on cerebral lactate uptake and , in turn , on the cerebral metabolic ratio during exercise is not known . Sodium bicarbonate ( Bicarb , 1 M ; 350-500 ml ) or an equal volume of normal saline ( Sal ) was infused intravenously at a constant rate during a '2000 m ' maximal ergometer row in six male oarsmen ( 23±2 years ; mean±S.D. ) . During the Sal trial , pH decreased from 7.41±0.01 at rest to 7.02±0.02 but only to 7.36±0.02 ( P < 0.05 ) during the Bicarb trial . Arterial lactate increased to 21.4±0.8 and 32.7±2.3 mM during the Sal and Bicarb trials , respectively ( P < 0.05 ) . Also , the arterial-jugular venous lactate difference increased from-0.03±0.01 mM at rest to 3.2±0.9 mM ( P < 0.05 ) and 3.4±1.4 mM ( P < 0.05 ) following the Sal and Bicarb trials , respectively . Accordingly , the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials : from 5.8±0.6 at rest to 1.7±0.1 and 1.8±0.2 , respectively . The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and , therefore , the decrease in the cerebral metabolic ratio .
48406
Intervention_Pharmacological
Sodium bicarbonate
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Intervention_Pharmacological
normal saline
48408
Intervention_Pharmacological
ergometer row
48409
Outcome_Other
promote cerebral lactate uptake
48410
Outcome_Physical
pH
48411
Outcome_Physical
Arterial lactate
48412
Outcome_Physical
cerebral metabolic ratio