Abstract. Myocardium includes typical and atypical cardiomyocytes -pacemakers, which form the cardiac conduction system. Excitation from the atrioventricular node in normal conditions is possible only in one direction. Retrograde direction of pulses is impossible. The most important prerequisite for the work of cardiomyocytes is the anatomical integrity of the conduction system. Changes in contractile force of the cardiomyocytes, which appear periodically, are due to two mechanisms of self-regulation -heterometric and homeometric. Graphic course of the excitation pulse propagation along the heart muscle more accurately reveals the understanding of the arrhythmia mechanism. These models have the ability to visualize the essence of excitation dynamics. However, they do not have the proper forecasting function for result estimation. Integrative mathematical model enables further investigation of general laws of the myocardium active behavior, allows for determination of the violation mechanism of electrical and contractile function of cardiomyocytes. Currently, there is no full understanding of the topography of pacemakers and ionic mechanisms. There is a need for the development of direction of mathematical modeling and comparative studies of the electrophysiological arrangement of cells of atrioventricular connection and ventricular conduction system. IntroductionThe most important features of the myocardium are automatism, excitability, conductivity, contractility and refractivity. Automatism of the heart lies in the ability of rhythmic contractions of myocytes under the influence of the pulses, occurring in the heart.The myocardium includes typical and atypical cardiomyocytes -pacemakers, which form the cardiac conduction system. The latter provides automatism of cardiac contractions, as well as the coordination of the contractile function of myocardium of atria and ventricles. The first sinoatrial node of the system is a major center of automatism, i.e., the first-order pacemaker. Excitation is transmitted from the sinoatrial node to the cells. It reaches the atrioventricular node (second-order node) going along special conducting bundles from the atria. Atrioventricular node can generate pulses itself. Excitation from the atrioventricular node in normal conditions is possible only in one direction. Retrograde direction of pulses is impossible. Third-order node provides rhythmic automatism of the heart action. It is located in the bundle of His and in the Purkinje fibers. Automatism centers, which are located in the conduction system of the ventricles, are called third-order pacemakers. The frequency of myocardium activity is generally defined by sinoatrial node. It governs all underlying conductive system formations, and it "pushes" its rhythm upon them [1,2].
Provision of high efficacy and quality of drugs developed based on nanotechnology is possible only in case of compliance with the requirements for the development, study, introduction and production of new pharmaceuticals. While determining the toxicological characteristics of substances, determination of genotoxicity and cytotoxicity is the first stage, the purpose of which is to determine the ability to induce primary DNA damage, as well as the possible negative effects on cell cultures. Taking into account the need for the introduction of new antimicrobial agents it is reasonable to develop combined agents that would have better efficacy and safety indicators. The studies of nanosilver-based drugs acting against antibiotic-resistant microorganisms, cytotoxicity and genotoxicity study of nanocomposite, finely dispersed silica and silver nanoparticles produced by alkaline single cell-gel electrophoresis assay are of significant scientific and practical interest. It has been demonstrated that finely dispersed silica nanocomposite with silver nanoparticles has no genotoxic properties, and its cytotoxicity disappears at concentrations below 0.007% [1 -3].Creation of functional nanomaterials and nanodevices is the most promising using the nanoparticles obtained by the chemical solution methods. These methods allow producing nanoparticles, especially from precious metals such as gold and silver, with a profusive variety of composition, structure, shapes and sizes.Possible applications of nanoparticles are not limited to a certain range. They are widely used for diagnostics and treatment of various diseases, including cancer. They are also used in immunochemical studies. So, they have been extensively studied in a new sect of experimental medicine, which is now called "nanomedicine". According to the literature it is known that, in particular, the silver nanoparticles may be used to produce a wide range of materials with antibacterial properties. At the same time, it has been found over the past few years that different nanoparticles when they enter the body, can lead to the development of serious diseases (nanopathologies). It is also emphasized that metal nanoparticles can enter the body in different ways, for example, through the mucous membranes of the respiratory tract and digestive system and through the skin when using cosmetics. They can penetrate through the bloodstream as an ingredient of vaccines and serums, etc. The risk of the spread of diseases of that type (nanopathologies) has been still not entirely investigated or realized. However, their importance is great today and in it is obvious that it will increase in the future. The determination of the causes of "harmful" (pathological) effect of nanoparticles and development of the ways to control the manifestations of diseases associated therewith are still going on. The question raised by the penetration of nanoparticles into the body remains an open one. Therefore, this area is now becoming the subject of the new and developing sect in the modern exper...
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