Determinants of oxygen delivery and hemoglobin saturation during incremental exercise in horses

Abstract

Increases in CO, [Hb], and O2 extraction contributed equally to increased VO2 during exercise. Higher PCO2 did not provide an independent contribution to shift in the oxyhemoglobin dissociation curve (OCD) in venous blood. However, lower PaCO2 shifted the curve leftward, facilitating O2 loading. The shift of ODC resulted in minimal effect on O2 extraction because of convergence of the ODC at lower values of PO2. Decreased pH appeared responsible for the rightward shift of the ODC, which may be necessary to allow maximal O2 extraction at high blood flows achieved during exercise.