A model for heterogeneity of kinetics of albumin transport in the renal cortical interstitium

Abstract

A model is proposed for the kinetics of the albumin pool of the renal cortical interstitium. The interstitial albumin pool is assumed to consist of a large ensemble of subunits, each of which acts as a single well-mixed compartment. The turnover rate constants are assumed to be statistically distributed over subunits according to the Gamma distribution. The resulting model allows estimation of both the mean and the variance of the distribution of rate constants within a kidney from experimental measurements of albumin specific activity in arterial plasma and renal lymph. The fit of this model to experimental data was found to be better than that of a single well-mixed compartment. Results are shown for normal rats, rats under physiological stress (hydration), and rats with a pathological condition (diabetes). An increased heterogeneity of the within kidney turnover rates was indicated under both conditions of stress and pathology.