Erythrocyte volume in acifified venous blood from exercising limbs.

Fatiguing muscular exercise of short duration (7-9 min) with the arms produced large increments of pCO (>+30 mm Hg) and hydrogen ion concentration in venous blood from the working limbs. On the basis of these biochemical changes it might be expected to find a volumetric increase in the red cell of venous blood, since more osmotically active ions entered the erythrocytes through the chloride shift mechanism. However simultaneous measurements of mean corpuscular red cell volume (MVC) and mean corpuscular hemoglobin concentration (MCHC) failed to demonstrate a measurable change in the size of the erythrocyte in the acidified venous blood. The concomitantly determined significant elevation of the plasma osmolarity (+7.7%) suggests that in vivo the human red cells from venous blood in exercising limbs maintain a constant volume through counteracting osmotic forces in spite of large hematological changes. [ABSTRACT FROM AUTHOR]