Biological applications of kinetic analysis of a two-compartment open system

Abstract

Complex metabolic steady state systems in which a central compartment (blood) exchanges compound with independent peripheral compartments (tissues), with synthesis and loss of compound occurring in the system, are examined. Factors that result in the simplification of complex biological systems into two-compartment open systems are discussed. Equations are derived for the two-compartment open system which allow calculation of: compartment size for central and combined peripheral compartments, total rate of exchange between these compartments, and total rate of synthesis and loss of compound from the system. Data required for these calculations can be obtained with relative ease from the accessible central compartment. Thus, a tracer dose of labeled compound is introduced into the central compartment and the specific activity-time relations of the compound are determined. Values derived by graphical analysis of this curve and knowledge of the dose of labeled compound administered are the only primary data needed to determine the parameters of the system. Practical applications of this analysis to model and biological systems are presented. Submitted on March 13, 1961