Diffusion coefficients of oxygen and hemoglobin as obtained simultaneously from photometric determination of the oxygenation of layers of hemoglobin solutions

Abstract

The oxygenation of layers of deoxygenated hemoglobin solutions after a sudden exposure to a gas containing oxygen at a partial pressureP ₁ has been studied by a photometric method. Layer thicknesses varied between 50 and 250 μm, hemoglobin concentrations between 0.1 and 0.34kg/l, and oxygen partial pressures between 4.65 and 93.1 kPa (35 and 700 mm Hg). The diffusion chamber containing the layer of hemoglobin solution permitted a step change in gas atmosphere without changing the optical apparatus constant. The following results were obtained: The oxygen saturation increase is independent of the layer thickness when expressed as a function of time divided by layer thickness squared (normalized oxygenation time). This justifies the assumption of chemical equilibrium between oxygen and hemoglobin in the range considered. The oxygen saturation increases proportionally to the square root of time over a wide range of oxygenation as expected. This range reaches to almost 100% oxygenation atP ₁=93.1 kPa (700 mm Hg) but less far asP ₁ is lower. Thus at highP ₁ values there is a sharp boundary between the oxygenated and deoxygenated part of the layer allowing the application of the advancing front concept. Fitting the theoretical equations derived in a preceding paper to the experimental results provides simultaneous values of the oxygen permeability (or, knowing oxygen solubility, of the oxygen diffusion coefficient) and of the hemoglobin diffusion coefficient. These values agree fairly well with values obtained by other authors from experiments yielding the diffusion coefficients of oxygen or hemoglobin separately.