The influence of putrescine low concentrations on contractile activity of myocardium in large and small laboratory animals and possible mechanisms of its direct and/or mediated influence on morphofunctional state of cardiomyocytes was studied. Single intravascular injection of 10-8 mg/ml putrescine to mice was accompanied by elevation of functional indices of heart contractile functions, which were expressed as the increase of heart mechanical contractions amplitude, increase of the apical potential in electrocardiogram. No signs of rapid or reduced heart rate were observed. Echo-tests/ultra-sound/in young puberal male pigs revealed that already in a minute after the injection of putrescine at the same concentrations as administered to experimental mice, the contractile ability of myocardium increased. This latter was expressed in increase of emission fraction of the left ventricle of heart. The most positive inotropic effect of putrescine was observed on the fourth minute after the injection of putrescine. The indicated parameters were normalized, ie reached the control values on the tenth minute of the experiment. Structural alterations characterising the high contractile ability of myocardium of the left ventricle in experimental mice were revealed by phase-contrast microscopy. With the help of enzyme immunoassay, it was established that on the 20th minute post injection of putrescine the content of adrenalin was considerably increased in heart, adrenals, and blood serum. The established fact of activation of synthetic processes occurring in the medulla of adrenal glands was confirmed by means of fluorescent microscopic research that allowed to register structural changes in endocrynocytes testifying to their hyperfunction.

On the background of an increase of intracellular ionised calcium content, the decrease of adrenergic nerve fibrils number with low content of noradrenaline was observed in myocardium of experimental animals. Due to the research performed, the conclusion might be drawn suggesting that the positive inotropic effect to heart under the conditions of injection of putrescine to experimental animals is mostly conditioned by processes of activation of catecholamine synthesis in the adrenals followed by their enhanced inflow into blood and heart.