A possible carbon monoxide shuttle in the lung

The Coburn, Forster, Kane Equation (CFKE) describes a current understanding of the physiology of lung uptake and excretion of carbon monoxide (CO). The lung mean capillary PCO is an important term in this equation because it drives CO excretion and functions as "back-pressure" during uptake of exogenous CO. Results of previous studies have indicated that the mean capillary PCO of normal human lungs is equal to values calculated using the Haldane Equation, as described by the CFKE. The physiological explanation of how this parameter is set at this level is unknown. As a possible explanation, this study tested a hypothesis that a CO shuttle could be involved. Results of calculation-simulations indicate that a CO shuttle operates in a single alveolus model and imply that it could function as a determinant of the lung mean capillary PCO.