Adrenoceptors in Dopaminergic Regulation of Rat Myocardial Contractility in Rats During Ontogeny.

The effects of different dopamine concentrations on contractility of myocardium with blocked α- or β-adrenoceptors were examined in vitro in 21- and 100-day old rats. In myocardial strips with blocked α-adrenoceptors, dopamine (10-5 M) increased the right atrial contractile force. By contrast, this neurotransmitter (10-9 -10-5 M) reduced the contractile force of atrial and ventricular strips with blocked β-adrenoceptors.