Antiarrhythmic properties of a new Suphan-based combined preparation and their possible mechanism of realisation

Considerable potentiation of antiarrhythmic and antifibrilation effects of two cardiotonic agents, Suphan and the Na-channel blocker L1, was found in the model experimentsin vivo with early occlusion and reperfusion arrhythmias. Suphan in combination with L1 inhibited the rise of intracellular Ca²⁺ (by about 70%) in isolated cardiomyocytes incubated under hypoxic conditions. Translated fromByulleten' Eksperimental'noi Biologii I Meditsiny, Vol. 125, No. 1, pp. 59–62, January, 1998     

Estimation of Na-blocking efficiency of rihlocaine and its combinations with low-molecular-weight polymers on isolated rat cardiomyocytes

The effect of glucose-base polymers (dextrans with relative molecular weight 10, 40, and 70 kD) and vinylpyrrolidone (polyvinylpyrrolidone: 10, 24, and 40 kD) on changes in the sarcoplasmic Na⁺ concentration in stimulated cardiomyocytes (1.0 Hz, 10 msec, 60 mV) were examined. In the concentration range of 1–100 μM, the polymer preparations produced cardioprotective effect on cells incubated under hypoxic conditions; the effect depended on the nature and molecular weight of the polymer. Rihlocaine (25 μM) inhibits by 42% elevation of intracellular Na⁺ induced by plasma membrane depolarization. Dextran 40 is shown to significantly increase Na-blocking effect of rihlocaine. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 12, pp. 649–651, December, 1997     

Anin vitro study into the mechanisms of lidocaine and befol actions on sodium exchange in normal and hypoxia-exposed rat cardiomyocytes

Using benzofuran isophthalate, a fluorescent probe for sodium ions, intracellular (sarcoplasmic) Na⁺ concentrations ([Na⁺]_i) were estimated in cardiomyocytes isolated from the left ventricle of rats. Lidocaine (1–100 μM) had little effect on [Na⁺]_i in resting (unstimulated) cardiocytes, while befol lowered it by virtue of its inhibitory effect on Na/H exchange. In cardiomyocytes exposed to “chemical” hypoxia (produced by 5 mM KCN+30 mM 2-deoxyglucoses). [Na⁺] were three times higher than in resting cells, and the Na-blocking effects of both lidocaine and befol were much stronger. When these two drugs were used together, potentiation of these effects was observed, which may be accounted for by their action on different Na-transporting systems. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 5, pp. 45–47, July, 1996     

Comparison of antiarrhythmic activities of rihlocaine and lidocaine

In different models of arrhythmia, the local anesthetic rihlocaine (rinocaine) exhibits a higher (or comparable) antiarrhythmic activity and therapeutic spectrum than that of lidocaine. Antiarrhythmic activity of rihlocaine may be associated with its effect on sodium and, to a greater extent, on calcium channels. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 11, pp. 517–520, November, 1996     

The role of neurotropic component in therapeutic effect of antiarrhythmic drugs

Acute experiments on anesthetized cats with neurogenic atrial fibrillation showed that the antifibrillatory effect of procainamide, lidocaine, and ethacizin correlated with their vagolytic rather than with cardiotropic activity. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 3, pp. 353–356, March 1999     

Estimation of cardiomyocyte transmembrane potential with potential-sensitive fluorescent probes

Transmembrane potentials on the plasma (Δφ₄) and mitochondrial (Δφ_m) membrane of isolated rat cardiomyocytes were estimated using the potential-sensitive fluorescent probe DSM. The values were −93±4 and −196±11 mV, respectively. Sufan significantly decreased the reduction of Δφ_m induced by chemical hypoxia. The effects of antiarrhythmic drugs on changes in Δφ_p were studied using the fluorescent probe dis-C₃-(5). Lidocaine, novocainamide, richlocaine, and leocaine blocked depolarization of the myocyte plasma membrane induced by electrical stimulation and did not affect the Δφ_m. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 11, pp. 594–597, November, 1998     

Effect of repeated complete starvation on quantitative parameters of rat cardiomyocytes

Sixty-four male Wistar rats were subjected to repeated complete starvation with free access to water. Each starvation period lasted 6 days and was followed by a 7-day recovery period. The concentration of cardiomyocytes (CMC) and their total number in the left ventricle (LV) were measured after alkaline dissociation of the myocardium. The volume density of muscle fibers and their absolute total mass in the LV were determined by stereological analysis. It is shown that after 6 successive starvation periods the proliferative potential of the CMC population is reduced. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 6, pp. 658–660, June, 1994 Presented by D. S. Sarkisov, Member of the Russian Academy of Medical Sciences     

Stereological ultrastructural analysis of rat cardiomyocytes after total hyperthermia

Hyperthermia results in the suppression of intracellular regeneration in cardiomyocytes, manifested as intensified lysis and destruction of organelles, and leads to myocardial atrophy. Intracellular reorganization of cardiomyocytes is characterized by increases in the volume and surface density of myofibrils, sarcoplasmic reticulum, and T system. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 1, pp. 96–100, January, 1994 Presented by V. A. Trufakin, Member of the Russian Academy of Medical Sciences     

Intracellular reorganization of rat cardiomyocytes following transfer to high latitudes

It is shown that as soon as the 1st day after transfer to high latitudes, the regenerative processes are suppressed in some cardiomyocytes, this manifesting itself in lytic changes of the sarcoplasm and organelles in the perinuclear zone. After flight in the middle latitudes morphological signs of disturbances in the processes of intracellular regeneration are observed only toward the end of the experiment. Intracellular spatial reorganization of cardiomyocytes for transfer to high latitudes and for flight in the middle latitudes has a stereotypic pattern and primarily manifests itself in an increase of the volume density of myofibrils and a decrease of this parameter for mitochondria. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 5, pp. 538–542, May, 1994 Presented by V. P. Kaznacheev, Member of the Russian Academy of Medical Sciences     

Effects of isoproterenol and suphan on the concentration of free calcium ions in isolated cardiomyocytes: a comparative study

Isoproterenol and suphan, two cardioactive drugs with different mechanisms of action, are studiedin vitro for their effects on calcium homeostasis in myocardial cells. Isoproterenol lowers the basal Ca²⁺ level in resting cardiomyocytes and potentiates its rise in these cells after their induction. Suphan stimulates reversible elevation of the diastolic Ca²⁺ concentration, causing increased calcium accumulation in the sarcoplasmic reticulum of cardiomyocytes. In anin vitro model of hypoxia, the Ca response to isoproterenol is significantly reduced, whereas that to dibutyryl cAMP is retained. The effect of suphan on the Ca²⁺ content of cardiomyocytes exposed to “chemical” hypoxia is 30–50% higher than its effect on the Ca²⁺ content of intact cells. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 8 pp. 170–172, August, 1996     

Comparative study of antiarrhythmic effects of methacizin and its components under conditions of neurogenic atrial fibrillation

Antifibrillatory effect of methacizin under conditions of neurogenic atrial fibrillation in cats was due to its vagolytic rather than cardiotropic activity. The immediate antifibrillatory effect of methacizin surpassed that of its components (ethacizin and ethmozin). However, 30 min after administration the antiarrhythmic effect of methacizin did not differ from that of ethacizin alone. Translated fromByulleten's Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 9, pp. 291–293, September, 1999     

Chondriome ultrastructure of rat cardiomyocytes after apparent death and in the postresuscitation period

Twelve-minute blockade of blood circulation caused different changes in cardiomyocyte organelles, particularly in the mitochondria. The initial cardiomyocyte structure was restored within 3.5 h of the postresuscitation period. Ultrastructural changes in cardiomyocytes were observed again 1 month after resuscitation. They disappeared after 5 months. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 1, pp. 95–100, January 1999     

Quantitative ultrastructural analysis of rat cardiomyocytes after a prolonged stay in the mountains

Disturbances of intracellular regeneration in cardiomyocytes (CMC) are demonstrated in rats kept for a prolonged period in the mountains. These disturbances cause focal destruction and lysis of organelles. The spatial intracellular reorganization of CMC under these conditions is characterized by an increased volume and surface density of myofibrils and decreased volume density of mitochondria, agranular sarcoplasmic reticulum, and T-system. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 6, pp. 661–665, June, 1994 Presented by V. P. Kaznacheev, Member of the Russian Academy of Medical Sciences     

Clinical and experimental study of antiarrhythmic and antianginal effects of quaternidine

High antiarrhythmic activity of a new Russian antiarrhythmic drug quaternidine in ventricular arrhythmia was studied in 96 coronary patients by Holter monitoring, bicycle ergometry, and echocardiography. The drug had a positive impact on local kinetics in left-ventricular ischemic myocardium and some parameters of bicycle exercise test. The preparation possesses no arrhythmogenic effect. Experiments on 30 random-bred rats showed that the drug reduced the necrotic zone under conditions of experimental coronary occlusion. Experiments on 14 intact cats demonstrated that quaternidine had no effect on coronary bloodflow. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 130, No. 11, pp. 581–584, November, 2000     

Effect of psychotropic drugs on self-stimulation

Amphetamine and cocaine have been shown to facilitate septal self-stimulation. Morphine, imipramine, benactyzine, meprobamate,diazepam, chlordiazepoxide, phenobarbital, and DLK-25, in small doses do not affect, but in large doses inhibit this reaction. It is suggested that amphetamine and cocaine have a direct activating effect on the positive reinforcement system of the septum. The ineffectiveness of the other drugs is explained by the absence of a nervous substrate for negative reinforcement at the septal level. Comparative analysis of the effect of psychotropic drugs on septal and hypothalamic self-stimulation leads to the conclusion that the activating effect of psychtropic drugs on the positive reinforcement system depends on their action on the emotiogenic structures of the brain and not on structures responsible for the formation of motivations.Laboratory for the Search and Study of Measures for the Prevention and Treatment of Drug Addiction, Department of Pharmacology, Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 429–432, April, 1977.     

Inhibition of contractile activity of cultured rat cardiomyocytes in response to reduced oxygenation

Hypoxia completely abolishes the spontaneous contractile activity of cardiomyocytes. Once the original oxygenation is restored, the cells regain their functional activity, which exceeds the control level (particularly after a 2-h hypoxia). It can be assumed that the rapid restoration of cardiomyocyte functional activity is due to the preservation of a sufficiently high oxygen content and to the compensatory activation of glycolysis. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 2, p. 215–217, February, 1995 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Effect of boron on the ultrastructure of parathyrocytes and atrial cardiomyocytes

Ultrastructural shifts in parathyrocytes and atrial cardiomyocytes induced by long-term treatment with boron-containing water (250 mg/liter) were found against the background of boron accumulation. These changes are indicative of enhanced secretory activity of these cells. It is hypothesized that boron modulates the effect of parathyroid hormone and atrial natriuretic factor and the rate calcium-sodium exchange. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 7, pp. 111–114, July, 1997     

Mechanism of action of the new cardiotonic suphan on calcium exchange in cardiomyocytes

Effects of suphan, a new cardiotonic agent containing succinyl tryptophan, on the entry of Ca²⁺ into rat cardiomyocytes, its intracellular compartmentalization, and its exit from these cells were evaluatedin vitro. It was found that the recorded sulfan-induced rise of intracellular calcium was due to Ca²⁺ entering the cell via L-type calcium channels, and that a reversible reduction of its concentration in the sarcoplasm occurred through its accumulation in the sarcoplasmic reticulum and was blocked by the specific Ca²⁺-ATPase inhibitor thapsigargin (10 μM). Suphan did not alter the activity of Na⁺/Ca²⁺ exchange in a concentration range of 5–150 μg/ml. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 7, pp. 57–59, July, 1996     

Apoptosis of cardiomyocytes as extreme manifestation of regeneration and plastic insufficiency of myocardium

Alkaline dissociation of the myocardium from rats with modeled anthracycline cardiomyopathy revealed decreased absolute number of cardiomyocytes, disturbances in their intracellular regeneration, although no sings of necrosis were observed. Regeneration and plastic insufficiency of the myocardium due to structural changes in the nuclei and disturbances in myofibril reproduction resulting from selective suppression of synthesis of contractile proteins in the cardiomyocytes leads to the death of up to 30% cardiomyocytes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 9, pp. 336–341, September, 2000     

Atrial cardiomyocytes of a heterothermic animal in various physiological states

Hormone-producing cardiomyocytes of the right atrium of suslik were studied in summer and winter periods (the torpidity and spontaneous awake states). The hormone was shown to be intensely synthesized in summer. The intensity of this process decreased during hypothermia and increased during winter spontaneous awakenings. The role of these changes in the maintenance of water and salt homeostasis is discussed. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 9, pp. 353–356, September, 1998