Kinetics of homeostatic behavior of receptor-enzyme systems under the action of physiologically active compounds.

We describe two types of models. In the first one it is assumed that regulation of enzyme activity occurs by the product of the enzyme reaction. In the second it is assumed that concomitant action of ligand occurs on at least two targets with opposite effects (dual-action model). Kinetic analysis of models of the first type shows that homeostatic response with respect to the key metabolite of the receptor-enzyme system is possible only if the enzyme kinetics are described by the equation of zero order. In 'dual-action' models, the homeostatic behavior of the system is defined by the mechanisms of compensation of the ligand primary effect.