[The effect of neurotensin on the cardiovascular system].

Neurotensin is a peptide involved in regulation of cardiovascular system. Neurotensin immunoreactivity is found in myocardium, conduction system of the heart, intracardiac ganglion cells, coronary vessels. High content of this peptide is also determined in structures of sympathoadrenal system. This creates the possibility of hormonal neurotensin action on the heart following sympathetic activation. Neurotensin accelerates heart rate, increases myocardial contractility, affects central haemodynamics, regional blood flow and coronary circulation. Neurotensin modulates autonomic influences on the heart and plays role in mechanisms of cardiac arrhythmogenesis, especially in dynamics of vagally induced cardiac rhythm disorders. Cardiovascular effects of this peptide may be associated with direct influence on the heart and vessels, stimulating action on release of histamine and catecholamines and activation of capsaicin-sensitive afferent neurons which contain calcitonin-gene related peptide and substance P. Cardiovascular action of neurotensin is species dependent and it is followed by pronounced tachyphylaxis. Cellular mechanism of neurotensin action is associated with stimulation of phosphoinositide turnover, elevation of intracellular calcium and cyclic nucleotides level.