Analysis of lymphatic protein flux data: I. Estimation of the reflection coefficient and permeability surface area product for total protein

Abstract

The reflection coefficient ( σ P,f) and permeability surface area product ( PS f) were determined using lymph total protein fluxes in three different vascular beds: lung, intestine, and hindpaw. When protein flux ( J P), lymph flow ( J L) and concentration of protein in lymph and plasma are substituted into the Kedem and Katchalsky equation, the following equation results: J P = (1 − σ P,f ) ( (C P + C L ) 2 )J V + PS (C P − C L ) . At each lymph flow and protein flux state the above equation is linear in σ P,f and PS f. This method was used at several different lymph flow states in order to produce a family of lines relating σ P,f and PS f in any given capillary bed. These linear equations were then solved either graphically or numerically to obtain a σ P,f and PS f between any pair of protein flux states. For the intestine, σ P,f varied between 0.3 and 0.9 using data from several published sources. For the hindpaw data, σ P,f varied from 0.700 to 0.997. For the lung, only one σ P,f could be calculated using this approach and the calculated value was 0.73. From our analyses, it is quite clear that σ P,f is a function of the volume flow and is not equal to the osmotic filtration coefficient [ σ P,D of the relationship J V = K F,C( ΔP − σ P,D Δπ)] except for a homoporous capillary membrane. At the present time we do not have the necessary data to analyze our approach fully and future work should analyze not only total protein but each protein fraction present in lymph collected at as many physiological steady states as possible.