Does benzo[a]pyrene affect the heart embryonic development?

Benzo[a]pyrene is a polycyclic aromatic hydrocarbon of well proved toxic effect on animal cells and tissues. We used chicken in ovo developmental model to verify its influence on selected parameters of the heart rhythm and on the antioxidative defense in the heart tissue. We determined that the dose of 1 mg/kg weight of eggs of benzo[a]pyrene strongly activates the glutathione-dependent antioxidative system, but it do not significantly affect the heart conducting system of the chicken embryo. We postulate that further study on the benzo[a]pyrene action during embryonic development of birds is recommended.

Stability of Physiological Functions and Methods of Its Estimation

Problem of physiological functions stability is the important part of the theoretical physiology. P.K.Anohin´s basic ideas - the theory of functional systems and systemic approach to study of physiological functions have begun the development of theoretical physiology and mathematical modeling in biomedicine. In this paper methodological aspects of using of various biomodels for an estimation of stability of physiological functions are considered. Experimental, genetic, mathematical and computer biomodels are described. Practical techniques of an estimation of stability are illustrated on an example of stability of cardiovascular functions to stressor loads. Examples of different experimental models of stress and methods of estimation of stressor loads influence on cardiac electrical stability are described. Cardiac electrical stability was estimated by thresholds for ventricular fibrillation. Besides experimental, examples of mathematical and computer methods of an estimation of stability of cardiovascular functions to stressor loads are presented. Mathematical model that enables to investigate the stability of heart rate dynamics to stressor loads is based on quantitative characteristics of impulse conduction in heart conducting system. The model describes the phenomena observed at gradual increase of stressor intensity. It was shown the existence of a critical point of transition of heart rate dynamics from linear to chaotic mode. The results show that the greatest stability is notable for the linear regime. For this regime small errors in values of initial conditions can’t sharply change the initial dynamics of RR intervals.