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Biomedical subjects

L M Lobanok

Publications and source records attributed to L M Lobanok.

32 records · Page 2Linked to original sources
PubMedDate not supplied

[The short-term and long-term effects of gamma-irradiation on the inotropic reaction of the myocardium during the activation of alpha- and beta-adrenoreceptors].

The contractile function of myocardium was impaired and its inotropic response to stimulation of alpha- and beta-adrenoreceptors decreased at early times (1-30 days) following whole-body gamma-irradiation with a dose of 1.0 Gy. Six months after irradiation the response of the isolated myocardium to stimulation of adrenoreceptors increased to exceed that of intact animals. In a year the reactivity of the myocardium towards alpha-adrenoreceptor agonists remained high and its sensitivity of phenylephrine hydrochloride increased considerably; the response to beta-adrenoreceptor agonists was virtually absent.

Animals↗
PubMedDate not supplied

[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.). The maximum functional response of catecholamine injured hearts to stimulation of alpha- and beta-adrenoceptors reduced in both age groups, while the sensitivity of the myocardium to beta-adrenoceptor agonists in mature rats increased.

Aging↗
PubMedDate not supplied

[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 Factors↗
PubMedDate not supplied

[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. Stimulation of adrenoreceptors in the case of inadequate oxygenation increased hypoxic myocardial contracture, the increase being greater in adult rats.

Age Factors↗
PubMedDate not supplied

[The intensification of the vasodilator reactions of arterial vessels to stimulation of the beta-adrenergic receptors in the postradiation period].

It was shown with endothelium-containing and endothelium-denuded aorta segments that external gamma-irradiation of rats (6.0 Gy) results in intensification of vasodilatation reactions on beta-adrenoceptor stimulation by isoprenaline with maximum in 30th day of post-radiation period. This post-radiation alteration is not related with endothelium-derived relaxing factor.

Animals↗
PubMedDate not supplied

[The contractile reactions of aortic segments to noradrenaline in the immediate and late postradiation periods].

It is shown on isolated aorta preparations, that external gamma-irradiation of rats in dose 6 Gy results in intensification of endothelium-dependent relaxation which reaches of maximum in 30th days of post-radiation period. Constriction effect of norepinephrine on preparations without endothelium in remote terms after irradiation decreases with maximum on 90th days.

Animals↗
PubMedDate not supplied

[Modifying effect of incorporated 137Cs on the mechanism of adrenergic control of myocardial contraction].

Incorporated 137Cs (absorbed dose of 0.26 Gy) causes decrease of myocardial's contractile function and inotropic response to beta-adrenagonists effect, isoproterenol-stimulated adenylate cyclase activity and beta-adrenoreceptors affinity. Adrenergic effects, mediated by alpha-adrenergic structures on heart contractile function, on the contrary, become stronger, that is due to the increase of the receptors' density on sarcolemma surface.

Adenylyl Cyclases↗
PubMedDate not supplied

[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.

Accidents, Occupational↗
PubMedDate not supplied

[Regulation of glucose transport in rat thymocytes after chronic gamma-irradiation].

Chronic gamma-irradiation (1 Gy, 100 mR/hr) increases cell titre in rat thymus and decreases glucose transport activation by phorbol ester. Animals kept in the Chernobyl evacuation zone over a period of 30 days exhibit reduced thymus cellularity and decreased PMA (200 nM) stimulation of glucose uptake by thymus cells.

Accidents, Occupational↗
PubMedDate not supplied

[The effect of incorporated cesium-137 on the structure of the erythrocyte membranes].

The influence of incorporated cesium 137 (the absorbed doses of 0.26-0.08 Gy) on the erythrocyte membrane structure has been investigated. It has been shown that chronic internal exposure to gamma radiation causes structural reorganization of erythrocyte membranes at remote postirradiation times (in 3 and 6 months) that influences the annular membrane lipid.

Animals↗
PubMedDate not supplied

[Effects of prolonged gamma irradiation and hypoxia on bioelectrical activity of myocardial cells].

It was established that prolonged gamma-irradiation of rats leads to the decrease of amplitude and duration of action potentials of right atrial cells, attenuation of the dependence of these electrophysiological characteristics upon the stimulation frequency, depression of the interval of cardiomyocytes reaction on the hypoxia. The revealed post-radiation changes determine the reduction of function resistance of heart cells bioelectrical activity and promote the initiation of arrhythmias.

Action Potentials↗
PubMedDate not supplied

[Aorta dilatation after prolonged gamma-irradiation].

It is shown on isolated aorta preparations that prolonged gamma-irradiation of rats results in depression of endothelium-dependent and endothelium-independent vasodilatation responses to beta-adrenoceptors stimulation by isoprenaline and M-cholinoceptors by carbachol.

Animals↗