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Biomedical subjects

F Z Meerson

Publications and source records attributed to F Z Meerson.

At least 19 recordsLinked to original sources
PubMed1979

[Correlation of the parameters of myocardial contraction and relaxation in compensatory cardiac hypertrophy].

The parameters of myocardial contraction and relaxation were determined from the left ventricular pressure curves obtained in closed chest rabbits. One month after the creation of ascending aorta stenosis when the relative weight of the left ventricle increased by 54% as compared to the control, systolic pressure was higher by 42% and maximum rate of pressure development by 47%. This increase corresponded to the degree of left ventricular hypertrophy so that the load on the unit of myocardial mass did not change. No changes were found in the contractility index. The index of relaxation, however, determined by the relation between the maximum rate of relaxation and the developed pressure and characterizing the function of the myocardial relaxation system was 20% lower than that of the control. This was associated with the decrease of the diastolic pause by 27%. The slowing down of relaxation is one of the first and must' signs of compensatory function of the heart.

Animals↗
PubMed1979

[Effect of hypokinesia on the contractile function of the myocardium].

Rats were subjected to hypokinesia for two months and the contractile function of isolated papillary muscles was studied. Hypokinesia reduced significantly the isotonic contraction velocity which depended on the ATPase activity of the myofibrils; it also reduced the velocity and index of relaxation which depended on the functional capacity of the Ca++-pump of the sarcoplasmic reticulum. The maximum force of isometric contraction determined by the quantity of actomyosine bridges in the myofibrils did not change after hypokinesia. This complex of changes is contrary to that observed in adaptation to exercise, when the velocity of isotonic contraction and relaxation increases while the force of isometric contraction does not change. The possible mechanism of this stability of the contractile force during adaptation and readaptation of the heart is discussed.

Animals↗
PubMed1979

[Effect of emotional stress on the contractile function of human heart (according to the echocardiographic data)].

Cardiac function was studied by echocardiography in 12 healthy sixth-year students at mid-semester, immediately before taking an exam and 30 minutes after it. It was found that the emotional stress experienced prior to the exam is attended with an increase in cardiac output by one and a half times and external work by two. This increase of the pump cardiac function is ensured without any essential increase in the diastolic dimensions of the left cardiac ventricle at the expense of fuller blood ejection from the left ventricle and decrease of its residual systolic volume. Since the students had taken more than 50 exams in the past and were adapted to the pre-examination situation, the circulatory changes revealed may be regarded as adaptive providing for the rich flow of blood to the brain.

Adult↗
PubMed1979

Influence of adaptation to altitude hypoxia on the behavior of rats in a conflict situation.

Adaptation to altitude hypoxia under conditions of conflict between thirst and defensive motivation was studied. The subjects adapted to altitude hypoxia made three times more attempts to drink from a water bowl despite receiving an intense shock. Adaptation to altitude hypoxia increased the stability of an initiated drinking reaction over intense shock. In adapted animals that began to drink, the drinking response changed to defensive behavior with twice the shock intensity as in control animals. In the absence of conflict, there was no difference in the satisfaction of the thirst and the defensive motivation in animals adapted to hypoxia and in controls. Hence, the effect of adaptation to hypoxia consists in making the animals more capable of inhibiting the responses to defensive motivation under conditions where it is necessary to satisfy another vital motivation.

Adaptation, Physiological↗
PubMed1979

[Prevention of stress-induced and hypoxic heart lesions by means of an antioxidant ionol].

It was shown in experiments on male Wistar rats that activation of peroxidized oxidation of myocardial lipids and accumulation of hydroperoxides in the myocardium comprise the decisive link of the pathogenic chain of stress and hypoxic damages to the heart. Injection of a potent non-toxic antioxidant into the animals before exposure to the stress or hypoxia blocks the activation of peroxidized oxidation and prevents disorder of the contractile function and damage to the heart muscle appraised according to the elimination of enzymes from the myocardial cells.

Animals↗
PubMed1979

[Activation of lipid peroxidation in emotional-pain stress].

Accumulation of primary and secondary products of lipid peroxidation (PLP) in different tissues of Wistar rats under emotional-pain stress (EPS) was studied using UV-spectrophotometry and fluorescense of Schiff bases. It was shown that under EPS the amount of PLP increased mostly in the heart and to a lesser degree in the skeletal muscle and brain. An increase in hydroperoxidases in all the organs studied was less than that in the PLP end-products, i. e. flourescent Schiff bases.

Animals↗
PubMed1979

[Decrease in the stress reaction and the ulcerative lesions of the stomach under the influence of gamma-hydroxybutyric acid].

The effect of preliminary Na gamma-hydroxybutyric acid (GHBA) injection on the activation of adrenergic and hypophyseal-adrenal systems during emotional-painful stress and ulcerous affection of the stomach after the stress cessation was studied in experiments on rats. It was established that the preliminary GHBA administration inhibits stimulation of stress causing systems and thereby prevents ulcerous affection of the stomach mucosa. It is suggested that the activation of GHBA-ergic inhibiting system, which accompanies the stress, is a natural mechanism of limitation of the stress reaction and prevention of the stress affections.

Animals↗
PubMed1979

[Effect of emotional-pain stress on the contractile function and sensitivity to noradrenaline of cardiac muscle].

The effect of variations in the Ca concentration in the perfusate on the function of isolated hearts of control rats and of those who sustained the emotional-pain stress (EPS) was studied. It was found that the EPS sharply increased the cardiac response in the animals to shifts in the Ca concentration. A rise in the main parameters of the cardiac contractile function in response to an increased Ca concentration was more pronounced in rats after the EPS than in the controls. The sensitivity to noradrenaline decreased 2-fold as compared to the control animals. It is suggested that the growth of the relationship between the cardiac function and the Ca concentration in the animals after the EPS is caused by the damaged membranous mechanisms of Ca transport in the myocardial cells.

Animals↗
PubMed1978

[Effect of adaptation to physical loads on the contractile function and mass of the left ventricle of the heart].

Echocardiography was used to examine 20 highly trained athletes and 12 untrained persons at rest and during increasing physical load. It was established that in untrained persons the stroke volume in moderate and large physical loads increases mainly due to an increase in the diastolic output with the systolic output unchanged. In highly trained athletes the stroke volume with an equal load increases due both to growth in the diastolic output and to considerable decrease in the systolic output, i.e., due to the more complete ejection of blood from the cavity of the ventricle. As a result in trained patients a sufficient minute output in physical exertion is attained with less external work of the left ventricle and myocardial tension.

Adaptation, Physiological↗
PubMed1978

[Myocardial energy metabolic disorders in emotional-pain stress and the prevention of these disorders by using sodium gamma-oxybutyrate].

Marked disorders of energy metabolism in the heart muscle simultaneously with the development of ulcerous lesions of the stomach were revealed in animals which had suffered an emotional-pain stress (EPS). These disorders are displayed in the fact that two hours after EPS, the glycogen reserve in the animal's myocardium diminishes, resynthesis of glycogen and oxidation of the main substrates of the tricarboxylic acid cycle are inhibited, and malate dehydrogenase and possibly other dehydrogenase systems of the mitochondria are partly inactivated. Such decrease in the activity of the metabolic tracts is attended by depression of the force and rate of cardiac contractions revealed on inducing a high rate of contractions. The preliminary administration of sodium gammaoxybutyrate to a considerable extent prevents all the changes in the animal's myocardium occurring due to the effect of EPS.

Animals↗
PubMed1978

[Effect of hypokinesia on the contractile function and nervous regulation of the heart].

Prolonged hypokinesia caused cardiac deadaptation in rabbits which resulted in diminishing of the left ventricle speed of contraction and relaxation joined later by a decreased vascular resistance. As a result, the ejection velocity as well as the stroke volume and the cardiac output were normal. The decrease of the relaxation speed became more obvious at a high heart rate and resulted in shortening of the diastolic pause and diminishing of cardiac output. Hearts of the hypokinetic animals were characterized by normal maximal pressure developed by a unit of myocardial mass at aorta clamping, decrease adrenoreactivity, and increased cholinoreactivity. This complex of changes is contrary to changes observed in adaptation to exercise, but is similar to changes observed in the compensatory hypertrophy of the heart.

Adaptation, Physiological↗
PubMed1978

[Mechanism of the decrease in basal metabolism during adaptation to hypoxia].

Oxygen uptake fell by 40% in rat adaptation to the periodic action of hypoxia under conditions of pressure chamber. This phenomenon did not disappear in animals in the state of profound anesthesia, and, consequently, was independent of adaptation changes of the cortical regulation of the animal motor activity. A cut of oxygen uptake by half persisted with the action of cold, noradrenaline, and 2,4-dinitrophenol, uncoupling oxidation and phosphorylation, on the organism. Thus, economic expenditure of oxygen in hypoxia adaptation could not be fully explained by increase of oxydation and phosphorylation conjugation.

Adaptation, Physiological↗