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Biomedical subjects

B I Laptev

Publications and source records attributed to B I Laptev.

At least 19 recordsLinked to original sources
PubMed1992

[The protective effect of carnosine in hypoxia and reoxygenation of the isolated rat heart].

The effect of carnosine (15 mM) on the contractile activity of isolated rat hearts contracting in an isotonic regime (37 degrees C at a 5 Hz stimulation frequency) has been studied. Carnosine added to the perfusing solution had no effect on the contractile activity either in hypoxia or during reoxygenation but decreased it with a simultaneous increase in the coronary flow during reoxygenation. Carnosine inhibited by 60% the lactate dehydrogenase release from cardiac cells. A conclusion is drawn that the protective effect of carnosine is due to its membrane-stabilizing action which is implemented during inhibition of peroxidation of membrane lipids.

Animals↗
PubMed1992

[Functional heterogeneity of the atrial myocardium in patients with congenital and acquired heart defects].

In experiments on atrium trabeculae the heterogeneity of myocardium contractile activity in patients operated on for inborn or acquired heart defects was studied. Contractile activity was assessed in isometric regime of muscle drugs work. The degree of functional heterogeneity was reported to differ in myocardium biopsies from patients with inborn or acquired heart defects. The difference was expressed in susceptibility to stimulating action or electrical impulses and in the degree of the change of myocardium contractile activity. The study of human myocardium functional heterogeneity is likely to present a new approach to increase efficacy of the work of pathologically changed heart muscle.

Biopsy↗
PubMed1990

[The action of fenoptin on cAMP dynamics in the isolated guinea pig heart during contraction-relaxation].

The influence of finoptin and Ca2+ concentration decrease on cAMP dynamic during cardiac cycle in guinea pig isolated heart, activated by isadrin (3 x 10(-8) M), has been studied. In isadrin activation of adrenoceptors cAMP concentration increased by 50% during contraction and decreased during relaxation. Hypocalcium solution (0.15 mM) and finoptin decreased cAMP concentration and influenced its dynamic during cardiac cycle.

Animals↗
PubMed1987

[Role of Ca-calmodulin- and cAMP-dependent reactions in forming the cardiac cycle].

The mechanisms of regulation of calcium ion concentration in the heart muscle during cardiac cycle have been considered. A great deal of attention has been devoted to the interaction of Ca2+-calmodulin- and cAMP-dependent reactions in the heart contraction-relaxation processes. The hypothesis on the two-phase structure of cardiac cycle has been proposed. This hypothesis allows to explain some biochemical mechanisms in the positive inotropic effect of catecholamines, cardiac glycosides and caffeine.

Animals↗
PubMed1986

[Role of calmodulin in the contractile function of the myocardium].

The effect of phenothiazines-trifluoroperazine frenolone, majeptile and aminazine on contractility of papillar muscle of Wistar male rats associated with short-term Ca-concentration increase up to 4 mM has been studied. There has been found the parameter-relaxation index-the change of which under the effect of phenothiazines (10(-5) M in all the cases) made use of significantly correlates with the constants, which reflect the similarity of given agents with calmodulin.

Animals↗
PubMed1986

[Protective effect of aminazine in ischemia and re-perfusion of an isolated heart].

The effect of cholorpromazine on the degree of reduction of the myocardial contractility during reperfusion of the isolated heart after 5 minutes total ischaemia of rats or after 40 minutes ligation of the left coronary artery of the guinea pigs has been studied. It has been shown that in both cases the preparation shows protective effect. In experiments on vesicles of sarcoplasmic reticulum (SR) of rat's skeletal muscles has been established that chlorpromazine prevents from calcium pump of SR dissociation caused by lipid peroxidation activity or by adding phospholipase A2 to SR fragments. It has been concluded that chlorpromazine protective effect depends on its membranostabilized action.

Animals↗
PubMedDate not supplied

[Reserve of serum lipids for peroxidation during oxidative stress in rats].

The index quantitatively characterizing the serum lipids reserve for peroxidation (SLRP) was developed and evaluated in rats with simulated toxic (CCl4) hepatitis. The index represents a ratio of malondialdehyde (MDA) concentrations in serum before and after stimulation of peroxidation by Fe2+ ions (in the same sample). The index SLRP allows to evaluate direction and the intensity of imbalance among prooxidants action and the total activity of serum lipids antioxidant system even when there is no change of MDA basal level.

Animals↗
PubMedDate not supplied

[The effect of obzidan, finoptin and Ca2+ on the cAMP level during contraction-relaxation of isolated heart of guinea pigs activated with isadrin].

The beta-adrenoceptor blockade, slow inward calcium current blockade and calcium concentration decrease in perfusion solution were studied for their effect on cAMP oscillations during cardiac cycle in the isadrin-activated isolated heart of guinea pig. Isadrin activation (3 X 10(-8) M) of beta-adrenoceptors caused an increase of the cAMP concentration by 50% during the contraction. All the actions decreased an average level of cyclonucleotide in the myocardium as compared with isadrin and what is more, obsidan (10(-6) M) removed the cAMP oscillations almost completely, the hypocalcium solution (0.15 mM Ca2+) decreased their amplitude and duration, finoptin (3 X 10(-8) M) qualitatively changed the oscillation profile. The results obtained make it possible to suggest, that a change in the concentration of ionized calcium in myoplasma is one of the reasons inducing changes in the cAMP during the cardiac cycle.

Animals↗
PubMedDate not supplied

[The use of 2-component myocardial contraction for assessing the mechanism of action of inotropic substances].

The possibility of using two-component contraction of the myocardium to evaluate the mechanisms of action of cardiotropic pharmacological agents was studied. Caffeine, ouabain, low-natrium solution, varapamil, nifedipine and BAY K-8644 were used. It was concluded that the analysis of contraction component amplitude dynamics makes it possible to determine the effect of the pharmacological agents on the interrelated mechanisms of the delivery of Ca2+ into the myoplasm of cardiomyocytes from sarcoplasmic reticulum and through sarcolemma during a single cardiac cycle.

Animals↗
PubMedDate not supplied

Effect of calmodulin inhibitors on rat and guinea pig myocardial contractility.

The effects of phenothiazine drugs with different affinities for calmodulin (trifluoperazine, frenolone, majeptile and aminazine) on the contractility of rat and guinea pig papillary muscles were studied. The phenothiazine-induced changes in the contraction-relaxation parameters were shown to correlate with the degree of calmodulin inhibition. These parameters are relaxation-onset index, relaxation index and terminal relaxation index in rats, and relaxation index and maximal developed tension in guinea pigs. An essential role of calmodulin in myocardium relaxation in both animal species is postulated.

Animals↗
PubMedDate not supplied

[The effect of trifluoroperazine on cAMP levels in the rat myocardium during various phases of heart cycle].

Trifluoperazine, a calmodulin inhibitor, has been studied for its effect on cAMP content in rat heart tissue at various cardiac cycle stages with beta-adrenoreceptors stimulation by izadrine. When trifluoperazine is absent, the cAMP level is found to be decreased at the beginning of the cardiac cycle in comparison with the middle of the cardiac cycle. Trifluoperazine (6 X 10(-6) M) induces an increase of the content of cyclic nucleotides at the beginning of the cardiac cycle and has no effect on its level in the middle of the cardiac cycle. This leads to a decrease of the difference between cAMP concentrations in the defined cardiac cycle regions. The calmodulin-dependent reactions might be expected to play an important role in the regulation of the myocardium cAMP concentration change during the cardiac cycle.

Adenylyl Cyclases↗