Effect of increasing concentrations of serotonin and adrenaline on contractility myocardium of the right ventricle of the heart of adult rats

In recent years progress has been evident in studies of the importance of serotonin in the physiological and pathological processes of the body and its mechanisms. The role of the serotonin system in the development of diseases such as atherosclerosis, arterial hypertension, and ischemic heart disease is largely discussed. In the myocardium of mammals and humans two types of serotonin receptors (5-HT2 and 5-HT4) have been identified. The activity of the heart is also controlled by the action of catecholamines on the adrenergic receptors of cardiomyocytes. In the implementation of the contraction of cardiomyocytes in the hearts of humans and animals there is also activation of adrenergic receptors, such as β1, β4 and α1A. Serotonin and adrenaline are regulators and modulators of physiological processes in organism, which, under pathological conditions, turn into factors contributing to the development of the disease. In studies on myocardial contractility in vitro in adult rats we found that with an increase in each concentration of serotonin, depending on the dose, a positive inotropic response to the right ventricular myocardium was observed. The effect of serotonin at the last dose on the force of contraction of the right ventricle compared with the first dose increased by 48.3 %. However, with an increase in the dose of epinephrine, the positive inotropic response weakened. At the maximum concentration of 10.0 mM epinephrine, a negative inotropic effect of 10.4 % was observed compared to the previous concentration. Thus, despite the fact that the distribution and functional role of serotonergic receptors in the heart repeats the role of adrenergic receptors, the inotropic response of cardiomyocytes to serotonin and adrenaline is different.