[Modification of adrenergic regulation of heart function under effect of radio-ecological factors within 10-kilometer zone of the accident at Chernobyl nuclear plant].

Rats kept within the ten-kilometer zone of Chernobyl disaster over a period of 30 days exhibited a decreased heart function response to beta-adrenoreceptor stimulus, reduced density of the receptor structures in cardiomyocytes and their affinity to specific agonists. The number of beta-adrenoreceptors in myocardium cells was restored in 6 months, but their affinity and heart function response to the effect of beta-adrenoagonists remained decreased. No significant changes were observed in regulation influenced indirectly via alpha-adrenoreceptors.

[Post-radiation changes in cardiac contractility and responses mediated by beta adrenergic receptors in mature and old age].

Experiments were performed on isolated perfused hearts of rats of the middle and old age. The animals were irradiated with 60Co gamma-rays at a dose of 1 Gy and a dose rate of 2.7 x 10(-4) Gy/s.

[Age-related features of cardiac contractility and its adrenergic regulation in catecholamine damage to the myocardium].

Studies on isolated rat hearts showed that in contrast to 8-month-old animals, in 26-month-old rats the contractile activity of the myocardium increases by the 3rd day after administration of toxic adrenalin doses (1 mg/kg i.m.).

[Age-related characteristics of cholinergic regulation of the biomechanical function of the rat heart in hypoxia].

Hypoxia is shown to decrease chronotropic and inotropic responses of the isolated heart of mature rats to stimulation of M-choline receptors. In aged tissue hypoxia has no influence on the inotropic response to carbocholine effect. The results permit a conclusion to be made on the higher resistance of cholinergic mechanisms that regulate the cardiac function to hypoxic effects in aged animals.

[Age-related characteristics of adrenergic regulation of the contractile function of the heart in hypoxia].

Experiments were performed on isolated hearts of adult (8-10 months old) and aged (24-26 months old) rats perfused with the Krebs-Henseleit solution according to the method of Langendorf. It was demonstrated that when oxygen supply was insufficient (pO2 of the perfusion solution-100 mm Hg), the chronotropic reaction of the heart to the stimulation of alpha- and beta-adrenergic receptors with phenylephrine hydrochloride (5 x 10(-7)--10(-5) M) and isoprenaline (10(-9)--10(-6) M), respectively, increased in adult rats and decreased in aged animals. Positive inotropic effects of adrenoagonists in hypoxic hearts diminished but their values as well as those at adequate oxygenation (pO2 = 600 mm Hg) were higher in aged rats.