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Biomedical subjects

R S Orlov

Publications and source records attributed to R S Orlov.

At least 37 records · Page 2Linked to original sources
PubMed1980

[Effect of gamma-aminobutyric acid and its analogs on the smooth muscle of veins].

Effect of gamma-aminobutyric acid (GABA) and its agonists, phenibut, phenylpyrrolidone and LGPI-29, on contractility of smooth muscle cells was studied on an isolated rat vena porta. The contractility was recorded by a rapidly operating 6MH-1B mechanotrone to show that the solutions of GABA and those of phenibut (to a less extent) exert a distinct inhibitory effect on smooth muscle cells of the rat vena porta at a concentration of 10--20 mM. Phenylpyrrolidone and LGPI-29 did not decrease vascular tone. Depolarization of the cell membrane did not interfere with the inhibitory effect of GABA and its agonists on smooth muscle cell contractility of the rat vena porta.

Animals↗
PubMed1979

[Adrenergic and cholinergic mechanisms of the contractile reactions of major blood vessels].

Epinephrine, norepinephrine, and isoproterenol induced circular contraction of isolated segments of canine intracerebral internal carotid artery. The alpha--and beta-antagonists inhibited the effects of catecholamines. Acetylcholine showed dual effects involving both dilation (5.10(-12)--5.10(-9) g/ml) and contraction 5.10(-8) g/ml and higher). Atropine inhibited both effects. The K+ depolarization abolished the contractile effects of norepinephrine and acetylcholine. The blockade of calcium permeability by Mn++ abolished the contractile effects of sympathetic and parasympathetic mediators.

Acetylcholine↗
PubMed1979

[Effect of the rest interval on the contractile activity of the myocardium].

Isolated strips of the heart auricles and ventricles of frogs at high stimulation frequencies revealed rest potentiation which depended both on the stimulation rhythm and on the duration of rest interval. Amphibians as well as warm-blooded animals and fish seem to display a possibility of Ca++ entering a cell during the period of rest via non-electrogenic calcium canals, but in amphibians this mechanism of the myocardium activation is compansatory, rather.

Animals↗
PubMed1979

[Effect of serotonin and histamine on the cellular contractile activity of the internal carotid artery].

In the experiments on isolated segments of the canine internal carotid artery it was shown that serotonin (5.10(-11)--5.10(-5) g/ml) activated the contractions. Histamine (5.10(-9) g/ml) induced dilation of isolated segments and its higher concentrations produced the contractile responses. Serotonin and histamine were shown to induce the contractions of the depolarized smooth vascular muscle. It is suggested that serotonin activates the inflow of extracellular calcium ions and histamine activates both the inflow of extracellular and the cut-flow of the intracellular calcium ions.

Animals↗
PubMed1979

[Effect of potassium ions on the contractile activity of renal artery smooth muscle].

Study of isolated segments of renal arteries in rabbits showed that decrease of potassium ion concentration in the bathing fluid was followed by increase in tension, while its increase from 5 meq/l to 10 meq/l was accompanied by gradual relaxation of vessel muscles and increase of their sensitivity to noradrenalin (NA). This relationship was lacking in segments activated with NA. The ability of NA and angiotensin to activate renal arterial muscles by electromechanic and pharmacomechanic coupling mechanismes was proved experimentally. The paper discussed the role of the cell membrane sodium potassium pump in vascular muscles.

Acetylcholine↗
PubMed1979

[Functional dependence of single muscle receptors on muscle activity].

In experiments on chloraloso-urethane anesthetized cats changes in spontaneous and induced spike activity of single muscle spindles and Golgi's receptors following a direct and/or indirect electrical stimulation of the muscle were studied. It was found that contractile activity of the plantar (phase) and heel (tonic) muscles decreased the spike activity of both muscle spindle and Golgi's receptors, the decrease in the phase muscle spindle activity being more considerable than in the tonic one.

Animals↗
PubMed1978

[Physiological properties of the blood vessel smooth muscles in experimental atherosclerosis].

The contraction of smooth muscle cells in response to the effect of catecholamines and potassium chloride was studied in experiments on isolated ring segments of the rabbit aorta under normal conditions and in experimental cholesterol atherosclerosis at its early developmental stages. It was found that at the early stages of atherosclerosis development the character of the contractile reactions was marked by changes which may be considered from the standpoint of disorder in the ion mechanisms of the interrelationships of sodium and calcium both on the membrane and within the smooth muscle cell, and from the standpoint of increased reactivity of chemically sensitive calcium channels of the membrane. The cause of these changes may be the accumulation of cholesterol, lipoproteins and acid mucopolysaccharides in the vascular wall at the early stages of atherosclerosis development.

Animals↗
PubMed1977

[Analysis of chrono-inotropy of the myocardium in poikilothermic animals].

Chrono-ionotropic interrelationships were studied in isolated strips of the myocardium of poikilothermous animals (frogs and fishes) in conditions of either stationary or transitional regimens of stimulation. In the stationary regimen, the rhythm-strength relation is simple and corresponds to a parabolic curve. While changing the lesser frequency of stimulation for greater one, both the positive and negative transitional abbreviating stirs were observed, in contrast to literature references. The phenomena of positive and negative transitional stairs were concluded to be unrelated to species while being a general biological form of the myocardium response to change of the stimulation rhythm.

Animals↗
PubMed1977

[Activation mechanisms of the contractile cells of cerebral arteries and veins].

In isolated strips of internal carotid artery and middle cerebral artery in humans, spontaneous electric and contractile activities were revealed. Low (35 degrees C) and high (40--41 degrees C) temperatures inhibited the development of spontaneous contractions. Under depolarization of the cells' membranes by potassium ions, no development of spontaneous electric or contractile waves occurred, while contractions of the tonic type were observed in arterial preparations. No spontaneous contractions were found in the cerebral veins.

Acetylcholine↗
PubMed1977

[Intravascular pressure and spontaneous lymph node contractions].

Interrelations between the spontaneous contractile activity and the level of intravascular pressure were studied on the isolated sections of lymphatic vessels. Spontaneous contraction proved to appear when the intravascular pressure was 1.5 cm H2O and decreased when it reached 10 cm H2O. The latent period of the origination of spontaneous contractile activity in rapid rise of pressure was shorter than such in its gradual rise. The amplitude and frequency of spontaneous contractions changed not only depending on the intravascular pressure value, but also on the rate of their change.

Animals↗
PubMed1977

[Effect of stretch on the contractile response of isolated portal vein smooth muscle].

The character of spontaneous activity of the isolated preparation was shown to be affected only by the first stretching stimulus which was due to release of the intracellular Ca. Active contractile responses to stretching at the peak of the contracture due to perfusion of the preparations with the Krebs sodiumless solution, are directly correlated with the speed of the stretching. Stretching of the preparations in calciumless solution elicited no active response.

Animals↗
PubMed1976

[Inhibition of spontaneous lymph vessel contraction evoked by transmural stimulation].

In isolated sections of mesenteric lymphatic vessels, the constrictory responses to transmural electrical stimulation were studied. Inhibition of the spontaneous rhythm occurring primarily at low frequencies was revealed as well as the inhibition following the excitatory effect of high--frequency stimulation. Analysis of the transmural inhibition showed the latter to occur as the result of activation of adrenergic nervous plexus and to be fulfilled by the beta--adrenoreceptors.

Animals↗