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 M) increased the right atrial contractile force. By contrast, this neurotransmitter (10-10 M) reduced the contractile force of atrial and ventricular strips with blocked β-adrenoceptors.

[State of adaptive systems of the body in boys aged of 11-15 years in the process of their age development, pubertal maturation and in the dynamics of the school year].

A comprehensive study of the functional state of the sympathoadrenal system (SAS) and adrenal cortex (AC) in boys aged of 11-15 years, was carried out depending on their age, puberty stage and academic year period, on the basis of indices of the daily adrenaline (A), noradrenaline (NA), 17-ketosteroids (17-KS) and 17-oxyketosteroids (17-OKS) excretion. A certain synchronism of the manifestation offunctional activity of the SAS mediator level, glucocorticoid and androgen AC function is determined as boys grow older and during their pubertal changes. At the same time the different dynamics of the studied indices in boys aged of from 14 to 15 years and by the V puberty stage is marked.

Adrenal gland hormones in primary school children.

It was found that in 8-9-year-old children, the hormonal part of the sympathoadrenal system more rapidly develops in boys, while the transmitter part develops more rapidly in girls. The androgenic and glucocorticoid function of the adrenal cortex matures earlier in girls. To the end of the school year, excretion of epinephrine and norepinephrine decreased, which attests to the development of fatigue.

Inotropic effect of dopamine on rat heart during postnatal ontogeny.

We studied the effect of dopamine in concentrations of 10(-9), 10(-8), 10(-7), 10(-6), and 10(-5) M on contraction strength of isolated myocardial strips from the right atrium and right ventricle of rats aging 21, 42, 56, and 100 days. Dopamine in a concentration of 10(-9) M had a positive inotropic effect in rats of various ages. Increasing the concentration of dopamine to 10(-7)-10(-5) M was accompanied by a negative inotropic effect on the heart.