ABSTRACT
We studied the effect of adrenoreceptor stimulation on the frequency of spontaneous activity and amplitude-time parameters of isometric contraction of the atrial myocardial strips from newborn rats, as well as the effect of Y receptor stimulation against the background of adrenoreceptor activation. After addition of Y1,5 receptor agonist [Leu31, Pro34] NPY (10-7 M), a tendency to a decrease in the effect of ß1,2-adrenoreceptor agonist isoproterenol (10-5 M) on the frequency of spontaneous activity and atrial myocardial contractility was observed. The age-related features of the effect of NPY on the frequency of spontaneous activity and contractility of myocardial strips from newborn and adult rats were revealed.
Subject(s)
Neuropeptide Y , Receptors, Neuropeptide Y , Rats , Animals , Neuropeptide Y/pharmacology , Receptors, Neuropeptide Y/agonists , Animals, NewbornABSTRACT
Selective agonist (Leu(31)Pro(34)NPY) and blocker (BIBP-3226) of NPY1 receptors were used to determine the type of NPY receptors involved in myocardial contraction. Experiments with isometric contraction of myocardial strips from mature rats showed that the agonist produced the most potent effect in a concentration of 10-7 M. In this concentration, Leu(31)Pro(34)NPY showed the greatest positive inotropic effect on the contraction of the atria and ventricles. In contrast, selective blocker BIBP-3226 reduced the force of myocardial contractions. Pretreatment of myocardial strips with this blocker abolished the positive inotropic effect of Leu(31)Pro(34)NPY, which attested to important role of NPY1 receptors in myocardial contraction.
