Simulation of Qualitative Peculiarities of Capillary System Regulation with Cellular Automata Models

Peripheral circulation can be divided in two components: continuous one, which includes continual fluctuation of muscular vessels diameters; and discrete one, which is caused by opening and closing of pre-capillary sphincters causes the activation-deactivation of capillaries. The state of each capillary sphincter depends on concentration of tissues vasodilator metabolites in the neighborhood of this capillary. Application of Cellular Automata simulation approach allows to study the behavior of separate capillary system as critically self-organized system and to investigate the different types of interaction between muscular arterial vessels and capillary network. Analysis of clinical data revealed significant difference in oxygen concentration in arterial and venous blood at normal conditions, at blood flow insufficiency conditions, and at hyperdynamic state of system circulation. This causes significant influence on fluctuation properties of capillary network and of tissues oxygen saturation. Depending on the state of system blood flow each capillary opens and closes at different thresholds of concentration of tissues vasodilator metabolites, closely correlated with tissues oxygen content. Different types of capillary network behavior have been simulated for various heart rhythm disturbances, which cause irregularity of fluctuations of system blood flow. Results of simulations were collated with clinical data and have a good correspondence with them. Regulation of peripheral circulation of blood includes its metabolically caused redistribution, stabilization of the main hemodynamic characteristics at the level of microcirculatory units and mass transfer inside them. The final stabilization of blood pressure occurs at the level of arterioles, then in microcirculatory unit performs a countertransport of oxygen and metabolites through the wall of the true capillary and arteriovenous shunting of blood (Chernukh&Alexandrov, 1984; Rushmer, 1986, e.a.). The blood flow in arteries is studied in most detail (Achakri e.a. 1994, Cavalcanti & rsino, 1996; Little, 1989; Rushmer, 1986, e.a.). However, the integral properties of peripheral blood