[Effects of high and low doses of vitamins A and E on the excitability of frog cardiomyocytes]

The effects of complex vitamins A and E on electrophysiological characteristics was investigated on frog cardiomyocytes. Large doses of vitamins A and E decreased the steepness of the action potential (AP) front, decreased the spike amplitude, shortened the plateau, decreased the steepness in the last phase of AP-repolarization, and decreased the rest potential level but considerably increased overshoot. The Ap-duration decreased noticeably. Small doses of vitamins decreased the spike amplitude, shortened the plateau, decreased the Ap-duration. We assume that complex of vitamins A and E can affect the cardiomyocyte membrane transport function, mainly due to the suppression of the slow membrane channels. The AP-front increase is less steep under the influence of vitamins. It is shown that the 0-phase depolarization speed decreases due to the inhibition of sodium channels.

[Protective lysosomal autoregulatory mechanism and its disorders in diphtheric intoxication]

Diphterial intoxication was established in rabbits by means of bolus 1 DLM/kg intravenous injection of diphterial toxin. Different types of N-acetyl-beta-1)-galactosaminidase's activity were determined in lysosomal fraction which had been obtained after ultracentrifugation of the left and right ventricles' tissue of the heart. It has been found that the mechanism of fixation's reinforcement of this enzyme exists in lysosomes in case of increasing of its activity. This mechanism was damaged on the different stages of diphterial intoxication that influenced negatively the heart's contractility.

[Effects and high and low doses of vitamin A on the excitability of frog cardiomyocytes]

The effects of the vitamin A lysosomal membrane labilizator on electrophysiological characteristics was investigated on frog cardiomyocytes. Large and small doses of vitamin A produced qualitatively identical effects: decrease of the steepness of action potential (AP) front, decrease of the spike amplitude, shortening of the plateau, decrease of the steepness in the last phase of AP-repolarization. The AP-duration decreased considerably. Large doses of the vitamin also reduced the rest potential level and insignificantly increased the heart contractions frequency. We assume that vitamin A can affect the cardiomyocyte surface membrane permeability, thereby decreasing its excitability due to suppression of the sodium and potassium.

[Effects of atrial natriuretic factor on the cardiovascular system and several parameters of renal excretory function in spontaneously hypertensive rats]

The influence of atrial natriuretic factor on several parameters of cardiovascular system and renal excretory function in spontaneously hypertensive rats has been investigated. The exogenously administered atrial natriuretic factor, not influencing the arterial pressure level and electrolyte concentration in the urine, at the same time breaks the links between APmax and the intensity of electrolyte excretion in urine.

[Spectrophotometric method for determining the stability of lysosomes from animal tissues depending on the hydrogen ion concentration]

Rapid spectrophotometric method of lysosome stability determination depending on hydrogen ion concentration is described. The time of analysis is decreased by 5-6 h in comparison with enzymic method. The process of lysosome degradation was linear at pH 6. The incubation mixture acidity dependence curve of lysosome lysis extend was complex. The lysosome lysis rate rapidly increased at pH much less than 6 less than pH. Lysosome incubation at 0-4 degrees C during 24 h decreased its sensitivity to incubation mixture acidity within the whole investigated pH range. Isolated lysosome acid resistance may be used as an index of its stability and lability in vivo and in vitro by various physicochemical factors. Percentage of initial absorbtion (A520) and initial lysosome lysis rate (delta A520/min) may be index of such effect.

[Dynamic changes in arylsulfatase activity in the initial period of acute focal myocardial ischemia in an experiment]

The increase in arylsulphatase activity in the ischemic zone has been shown by histochemical method in progressing acute myocardial ischemia. The increase in the enzyme activity in a so-called "intact" zone was less marked.

[Protective reaction of the myocardium in poisoning]

Intensive synthesis of collagen-like substance was revealed in the rabbit myocardium during experimental diphtheria intoxication. It was more marked in the right ventricle 24 hours after the injection of diphtheria toxin. Since similar changes (the substance was mainly formed around blood vessels) have been observed in other cases of toxic myocardial alterations (i.e. ethanol intoxication, injection of pharmacological agents, etc.), it can be assumed that it is a standard protective reaction of the altered heart to the penetration of toxic agents from the blood into the myocardial tissue.

[Spectrophotometric method of determining the osmotic resistance of lysosomes isolated from animal tissue]

Rapid spectrophotometric determination of animal tissue lysosome osmoresistance is described. The duration of analysis is decreased by 5-6 h, as compared to enzymatic method. The process of lysosome degradation was linear at 0.7 M sucrose concentration. The dependence of sucrose molarity on the extent of lysosome lysis was complex. The lysosome lysis rate rapidly increased at sucrose molarity less than 0.7 M. Lysosome incubation at 0.4 degrees C for 24 h increased their osmotic sensitivity within the whole investigated osmotic pressure range. Isolated lysosome osmoresistance may be used as an index of dynamic structural and functional state of these particles and the extent of their degradation caused by various physical and chemical factors in vivo and in vitro. The measure of the initial absorption (A520) and the initial lysosome lysis rate (delta A520/min), as well as biological half-life may be the index of such an effect.

[Afferentation of the heart in pathological states of the myocardium]

The state of afferent connections between sinoatrial node zone (SNZ) in the normal and affected myocardium (reversible ischemia, necrosis) and rostral parts of the brain cortex (RPC) was studied with the help of evoked potentials in acute experiments on cats. Interruption of afferent connections (SNZ-RPC) during reversible ischemia and experimental myocardial necrosis of the right ventricle was revealed. Ultramicroscopic data of SNZ studies as well as electrophysiologic changes registered in RCP during irritation of the peripheral part of the right vagus nerve and local application of GABA on SNZ suggest possible interruption of cardiac afferentation at the level of SNZ due to the mechanism of presynaptic inhibition.

[A modified highly sensitive spectrophotometric method for determining acid phosphatase activity in the animal liver]

A modified spectrophotometric procedure is described for estimation of acid phosphatase activity in rabbit liver tissue. Coefficient of instrumental sensitivity (SA/C = 0.029), apparent molar absorption (epsilon 820 = 30,500), relative sensitivity of measurement (Cmin = 0.18 mM) were calculated as well as main metrological patterns were evaluated, which showed that the procedure was highly sensitive, accurate and reproducible. Standard error did not exceed 1% and standard deviation was not above 5%.

[A rapid spectrophotometric method of determining heat-resistant lysosomes in animal tissues]

Rapid spectrophotometric method for the determination of thermoresistance in tissue animal lysosomes is described. The of analysis is decreased by 5-6 h, in comparison with enzymatic technique. The determination regimen was chosen in such a way that the process of lysosomal lysis was linear. The dependence of the incubation mixture temperature on the degree of lysosomal lysis was complex. The rate of lysosomal lysis rapidly increased at greater than 37 degrees C. Lysosome incubation at 0-4 degrees C for 24 h decreased its hypothermal (t = 10-30 degrees C), but not hyperthermal (t greater than 37 degrees C) sensitivity. Isolated lysosome thermoresistance may be used as an index of its stability and labialization in vivo and in vitro by various physico-chemical factors. The percentage of initial absorption (A520) and the initial rate of lysosomal lysis (delta A520/min), as well as melting temperature (Tmel) and biological half-life (t1/2) may be the measurements of such effect.

[Types of mitochondria destruction in the cardiac myocyte (from the data of scanning electron microscopy)]

Scanning electron microscopy has revealed three types of myocardial mitochondria degradation in intact rabbit heart: desquamation of the external membrane, mitochondria swelling with their following destruction, mini-focal ulceration of mitochondrial external membranes. There was a clear-cut daily and seasonal dynamics of the three types of degradation. Mitochondria degradation was much more pronounced in the fibrillating than in intact heart.

[Effect of geomagnetic storms on the state of heart mitochondria and their role in providing energy for myocardial contraction]

The experiments on intact rabbits have shown that geomagnetic storm breaks the relationship between the size of myocardial mitochondria and the degree of cardiac contractility, causes swelling and further destruction of mitochondria. Geomagnetic storm leads to a decline in the left ventricular contractility. The development of geomagnetic storm is associated with a significant strong positive correlation between the size of mitochondria and the blood level of free fatty acids.

[Change in the mitochondria of the left heart ventricle in the intact rabbit during the course of the day (based on scanning electron microscopic data)]

The myocardium of the left ventricle of intact rabbit was investigated by scanning electron microscopy during 24 hours, namely at 0, 6 a.m., noon and 6 p.m. It was discovered that the mitochondria reach the maximal volume at 6 p.m. and the minimal at 6 a.m. The qualitative differences in the mitochondria at different periods of the day are described. A correlation was established between the swelling of the mitochondria and some indices of heart function.

[Changes in the myocardial ultrastructure of the perfused rabbit heart under hypoxia]

Ultrastructure of rabbit heart left ventricle isolated according to Langendorf was examined under different conditions: in intact animals, during ligation of the coronary artery, and hypoxic heart perfusion. The intact perfused heart showed unmarked exo- and intracellular edema and moderate swelling of the mitochondria. During hypoxic perfusion, marked swelling and destruction of the mitochondria were noted. During ligation of the coronary artery, the heart was characterized by a high degree of mitochondrial heterogenicity. The correlation of the data obtained allowed one to reveal the myocardial adaptive-accommodative mechanism, (intermittent mitochondrial activity) that makes it possible to maintain the heart bioenergetics during coronary artery occlusion at a permanently high level.