Kinetics of unidirectional transport in multimembrane systems as influenced by binding to macromolecules.

The distribution of externally added low-molecular-weight solutes in systems comprising alternating membraneous and aqueous compartments with binding capacity is described for special conditions of unidirectional transport and linear (i.e., far from saturation) binding. The kinetics of the process valid for a certain time period is expressed as the sum of exponential functions of time, their number being equal to the number of compartments investigated. The coefficients of the equation involve the rate and equilibrium parameters of the process as well as the volumes and the connecting areas of individual compartments. The degenerated case resulting from the cellular structure of biosystems is also considered. The description is shown to agree well with the results of drug potency testing, bioactivity being used to monitor concentration of an effector in the receptor region.