New formulation of water and macromolecular flux which corrects for non-ideality: theory and derivation, predictions, and experimental results.

摘要: Classic irreversible formulation of coupled water and macromolecular transport across capillaries by Kedem & Katchalsky (1958) , even with subsequent refinements ( Spiegler Kedem, 1966 ), assumes explicitly that colloid osmotic pressure (π) is linearly related to concentration. It known, however, π concentration an accelerating function empirically expressed as a cubic equation Landis Pappenheimer, 1963 ). Using only basic rules thermodynamics Onsager, 1931 we rederived the flux equations in exact form. To render them approximately solvable, assumed mathematical continuity membrane incorporated Landis-Pappenheimer relationship. Results yielded giving different descriptors from classic (CF). Instead sieving coefficient (1 − σ), new (NF) gives parameter A which solute per unit volume when oncotic gradient zero. permeability-surface area product (PS), NF Φ “solute pressure” at zero flow. Relationships between σ, PS, A, are shown whereby differences CF can be investigated. Predictions were made comparing values expected experiment for variety variables using either or NF. show any sets lymph lymph/protein ratio, number inequalities expected: For reflection coefficient, σNF > σCF; PSNF PSCF; mean relative protein concentration, C/Cp(NF) Fr D . In venous perturbation experiments hindquarters 21 dogs, predictions upheld. Moreover, not closely predictive values. As others have noted, σ PS correlated capillary filtration; this relationship obliterated treatment, possibly indicating true flow dependency descriptors.