Frequency Of Heart Contractions Research Articles

The effect of technological stress on the biochemical parameters of the blood of ewes

In the course of the research, the effect of technological stress on the biochemical parameters of the blood of Ukrainian Mountain Carpathian sheep was studied before shearing and after it on the first and fifth day. Zootechnical, clinical-biochemical, biometric research methods were used. The research results showed that after shearing, stress in sheep of the first and second groups was clinically manifested by general depression, accelerated heartbeat and breathing. Such differences in the frequency of heart contractions and the number of respiratory movements in ewes can be explained by increased excitability of the nervous system due to shearing. The number of erythrocytes and leukocytes in the blood of sheep of both experimental groups before and after shearing was normal and did not go beyond physiological fluctuations. A slight decrease in blood parameters was detected in ewes of the first and second groups one and five days after the hygienic procedure. No significant difference in the number of erythrocytes and leukocytes was found between the experimental groups. Under the influence of stress factors, the content of total protein in blood serum decreased in ewes, especially one day after shearing in the experimental groups. After exposure to stressors, a decrease in urea content was detected in all experimental animals after one day and on the fifth day, which is due to the fact that under the influence of stress in the body, the breakdown of proteins and, accordingly, the level of the end products of protein metabolism decreases. As a result of shearing after a day, the cholesterol content in the blood of experimental sheep of the first and second groups probably decreased, with a slight tendency to increase after the fifth day. After exposure to stressors, the total lipid content of ewes of the first and second groups probably decreased on the first day, and a significant increase was observed on the fifth day. When the body is under stress, energy is wasted. He receives part of it at the expense of fats, which is why the content of total lipids in the blood of experimental animals decreases a day after a haircut. After shearing, the blood glucose content of all ewes increased, especially with a high probability in experimental animals after the first day, which is a consequence of the breakdown of increased glycogen. This indicates that these sheep had a stronger state of stress. After the fifth day, in the experimental ewes of the first and second groups after shearing, all the investigated indicators probably did not differ from those obtained before their shearing.

Cardiotonic activity of the aqueous extract of euphorbia poissonii on the isolated frog heart

Aim. The effects of the water extract of the leaves of Euphorbia Poissonii (Euphorbiacea) on frog heart contraction and its possible mechanism action were investigated. Method. By using the Langerdhorff model of the isolated frog heart preparation, the strength and frequency of heart contractions as well as cardiac output were measured under perfusion with test drugs. Results and conclusion. When assessed with digoxin and adrenaline as positive controls, the water extract (3 mg/mL) exhibited significant positive inotropic (70.00% improvement compared to baseline) and chronotropic (17.79% improvement) effects. Additionally, heart contractility was inhibited in the presence of propranolol and amlodipine, suggesting that the testing extract is having adrenergic properties. Reversible heart arrest was noticed at the dose of 6 mg/mL.

Coronarographic and magnetic-resonant study of the myocardium of rats for artificial hypobyosis

The one of newest future methods of anesthesia is the state of artificial hypobiosis. For detail studying this method with a possibility of its further introduction in clinical practice, and before – in conducting clinical studies, it is necessary to have specified data of pre-clinical studies. Among important methods that characterize the completeness of pre-clinical data are magnetic resonance imaging procedure and coronography of key vessels of the myocardium of rats. Coronography – is the rontgenological method of research that demonstrates the structural deformation and speed of the bloodstream of key vessels of the heart. Its principle is based on introducing a contrast substance including iodine in the peripheral vein of a patient with the further rontgenological scanning during several full cycles of circuit. In its turn, the magnetic-resonance imaging procedure of the myocardium – non-invasive method of the structural-diagnostic study characterizes 3D-model using the three-dimensional reconstruction of the cardiac muscle, and also demonstrates the volume of cardiac chambers, characterizing the dynamics of changes of the wall thickness. That is why just these methods were chosen for the detail characteristics of structural-functional changes of the myocardium of rats at artificial hypobiosis. In experiments there were used white outbred male-rats with mass 180-200 g, kept in standard vivarium conditions. The animals were divided in groups: control (intact animals) and experimental (artificial hypobiosis). The number of animals in each group n = 7. Experiments were conducted in correspondence of requirements of the “European convention about protection of vertebral animals, used for experimental and other scientific purpose” (Strasburg, France, 1985), According to general ethical principles of experiments, accepted by the first national congress of Ukraine on bioethics (2001). As a result of the conducted studies, it was demonstrated that the state of artificial hypobiosis favors the essential narrowing of the clearance of great vessels of the myocardium of rats, decrease of the frequency of heart contractions in six times comparing with the control one, and also decrease of the chambers of the cardiac muscle

Heart mechanical and hemodynamic parameters of a beetle, Tenebrio molitor, at selected ages.

The physiological processes that occur during the aging of insects are poorly understood. The aim of this study was to describe the changes in contractile activity and hemodynamic parameters of the heart that take place as the coleopteran beetle, Tenebrio molitor, ages. The frequency of heart contractions in beetles that had just undergone metamorphosis (median 24.7 beats/min) was significantly lower than the frequency of heart contractions in older beetles. In 56% of beetles that were<1week of age, a pattern of contractile activity with alternating periods of higher and lower contraction frequency was detected, suggesting that some posteclosion developmental processes occur during the first week of adulthood. All beetles that were 1week of age showed a regular rhythm of heart contractions (median 72 beats/min). In older beetles, abnormalities such as heart arrhythmias or heart arrest were observed. The incidence of arrhythmia as well as the arrhythmicity index was highest in beetles that were 8-18weeks old. The calculated stroke volume (SV) was also found to increase from eclosion to 12weeks of age, and then decreased as adults aged further. Interestingly, cardiac output increased gradually, but the ejection fraction did not change significantly with age.

Tactics of antihypertensive therapy in patients with hypertonic crisis complicated with hemorrhagic stroke

To determine an optimal tactics of antihypertensive therapy in patients with hypertonic crisis complicated with hemorrhagic stroke. We examined 86 inpatients, 42 men and 44 women, aged 46-87 years, with hypertonic crisis complicated with hemorrhagic stroke. The severity of neurological deficit, parameters of cardiac output and Kaplan-Meier survival curve based on the level of arterial pressure (AP) were assessed. The best survival rate of the patients with systolic blood pressure >162 mm Hg to the 20th min from the beginning of treatment with the greater rate of its increase was established. The efficacy of antihypertensive therapy did not depend on the baseline neurological deficit. The remote survival rate did not depend on such factors as sex, age, baseline AP level, AP, frequency of heart contractions, hematoma's volume.

RESUSCITATION OF VITAL ACTIVITY AFTER COLD ARREST OF RESPIRATION BY PHYSIOLOGICAL METHODS WITHOUT REWARMING THE BODY

The arrest of respiration during deep hypothermia means death, though at a low temperature the heart may rhythmically contract for 30–40 minutes more. The attempts of rewarming only shorten the time before the heart arrest. “The aim of the study” the attempts to develop the methods of stimulating the respiration and heart without rewarming the body. Calcium ions (Ca2+) are believed to accumulate in the nervous cells in cold. An excess of these ions inhibits the metabolism. Moreover it stimulates the cell proteases, which destroy the cell membranes. “Materials and methods” The work was carried out on wite rats 250-320 g in weight. We introduced disodium salt of ethylenediaminetetraacetic acid (EDTA) into the animals. The second method of blocking the mechanisms of the cold death was artificial respiration. “Results”EDTA reacts with calcium ions, decreases their quantity in the blood, and, consequently, in a complex manner in the cell protoplasm. Artificial respiration not only increases the flow of oxygen into an organism but also decreases the lowest temperature threshold of the cold death of an organism. “Conclusions” A decrease in the surviving threshold by 1.5-1.8oC is very important from the point of view of reanimation of an organism since to preserve life in the critical period of reanimation each 0.5oC are important. Prolongation of minimal frequency of heart contractions and maintaining a minimal arterial blood pressure in an overcooled organism given the body temperature of 11-12.5oC is a special problem of great interest associated with many physiological and biological parameters.

The force of the spontaneously contracting zebrafish heart, in the assessment of cardiovascular toxicity: Application on adriamycin

The heart of the zebrafish has been used extensively to assess the cardiotoxic effect of compounds, using the frequency of heart contractions as the main index of cardiac response to drugs. In this study, the force and the frequency generated by the spontaneously contracting zebrafish heart, isolated in saline, were found to be 0.87±0.05mN and 1.54±0.03Hz (n=6) respectively within the first hour of recording. Both values of force and frequency remained constant for over 8h. The advantage of prolonged vitality in the assessment of cardiovascular toxicity was shown using the well-known anticancer drug adriamycin, which has severe cardiotoxic side effects. At 10.0μM there was a 21.05±4.42% (p=0.02, n=4) decrease in the force of contraction, while the frequency was not affected after 3h treatment (p>0.05). At 50.0 and 100.0μM there was a 33.24±3.0 and 46.6±4.80% irreversible decrease in force (p<0.05, n=4), while a 18.02±4.07% and 16.16±4.07% reversible increase was observed in the frequency (p=0.02, n=4). These contradictory positive chronotropic and negative inotropic responses indicate the strong inhibitory effect of adriamycin on ventricular cardiomyocytes and its excitatory effects on auto-rhythmical pacemaker cells. If heart frequency was the only parameter used to assess the cardiotoxic effect of adriamycin, at the above range of concentrations, this compound would have been classified as non-cardiotoxic.