Diffusion Coefficient of Oxygen in Various Model Layers as Determined by Analysis of Time-Dependent Diffusion
To obtain an accurate oxygen diffusion coefficient for muscle tissue, the tissue is divided into several fractions. These fractions can be represented by myoglobin solutions, protein solutions, endothelium, lipid layers, etc. For each of these fractions an oxygen diffusion coefficient can be measured in vitro in a diffusion chamber. In general, the methods for measuring oxygen diffusion across these various layers or membranes can be divided into two types; steady state and nonsteady state measurements. The steady state methods yield the oxygen permeability of a layer (p 02), which is equal to the product of the oxygen diffusion coefficient (D02) and the oxygen solubility (a02). This implies that the determination of the diffusion coefficient from steady state measurements requires accurate solubility data. These may not be available for every type of model layer. From the nonsteady state measurements, however, the diffusion coefficient can be obtained directly [1,2]. Therefore, in this study the nonsteady state method was applied to determine the D02. The model layers that were used in the experiments were plain water layers, either confined to Millipore® filters or applied on top of a porous PTFE membrane.
KeywordsModel Layer Supporting Layer Diffusion Chamber Steady State Measurement Steady State Method
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