Alpha(1a)-adrenoreceptor participation in myocardial contractility regulation among newborn rats

Abstract

© 2019 Plant Archives. All rights reserved. The study was conducted on outbred newborn 6-7 day old rats. To stimulate alpha1A-adrenergic receptors, the pharmacological preparation A-61603 was used in concentrations of 10-9 - 10-6 mol. They studied the reaction of contraction force of isolated atrial and ventricular myocardial strips of the heart in response to the action of a selective agonist. Stimulation of alpha1Aadrenergic receptors depending on the concentration of agonist A-61603 caused multidirectional inotropic effects. A-61603 at concentrations of 10-9 and 10-8 mol leads to the decrease, and at the concentrations of 10-7 and 10-6 mol, to the increase of the atrial myocardial strips and ventricle contraction strength among newborn rat. In addition, the duration of a positive inotropic effect also depends on the concentration of the agonist. Our previous studies have shown that in the ventricular myocardium of adult rats, A-61603 in the concentration range of 10-9 - 10-6 mol causes only a negative inotropic effect. It should be noted that the nature of the inotropic effects of alpha1A-adrenergic receptors may depend not only on the activity of different signaling pathways triggered by both different subtypes and a separate subtype of receptors, but may also be associated with the features of activation and maturity of individual elements of one signaling system at different stages of postnatal ontogenesis.