Correction to: Peculiar Aspects in Influence of α<inf>1</inf>-Adrenoceptor Stimulation on Isolated Rat Heart (Bulletin of Experimental Biology and Medicine, (2016), 162, 1, (4-6), 10.1007/s10517-016-3530-z)

Correction to the article “Peculiar Aspects in Influence of α1-Adrenoceptor Stimulation on Isolated Rat Heart,” by T. L. Zefirov, I. I. Khabibrakhmanov, N. I. Ziyatdinova, and A. L. Zefirov, Vol. 162, No. 1, pp. 4-6, November 2016

Effect of Clonidine Hydrochloride on Isolated Newborn Rat Heart

The concentration dependenies of the chronotropic response and changes in blood supply to the isolated heart of 7-day-old newborn rats induced by application of α2-adrenergic receptor agonist clonidine hydrochloride in concentrations of 10-9-10-6 M were revealed. The minimum concentration of α2-adrenergic receptor agonist caused tachycardia, while higher concentrations led to bradycardia. The maximum effect manifesting in a decrease in coronary flow was recorded at the minimum concentration of the agonist, while the highest concentration had no effect on the coronary flow. When comparing these results with those obtained in control adult rats, we found that the most pronounced differences in the chronotropic effects were observed after addition of the minimum concentration of the α2-adrenergic receptor agonist: bradycardia in adult rats and tachycardia in newborns. The maximum differences in coronary flow parameters were observed after addition of α2-adrenergic receptor agonist in the maximum concentration that induced a two-phase response in adult rats and had no effect on the blood supply in newborns

Effect of α2-Adrenergic Receptor Stimulation on the Isolated Rat Heart against the Background of I<inf>f</inf> Blockade

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. The study examined the effect of α2-adrenoreceptor (α2-AR) activation against the background of preliminary blockage of If on the performance of Langerndorff-isolated rat heart. Stimulation of α2-AR in isolated rat hearts against the background of ZD7288 in concentrations of 10—9 M and 3×10—5 M changed the negative dynamics of myocardial inotropy to positive (by 25 and 38%; p'0.05). Activation of α2-AR produced opposite effects on HR. If blockade abolished tachycardia caused by activation of α2-AR; HR deceleration in response to α2-AR agonist against the background of If blocker in a concentration 10—9 M was 41% (p'0.05). We observed negative dynamics of coronary flow (by 38%; p'0.05) in isolated adult rat hearts after application of α2-AR agonist against the background of If blockade (10—9 M)

Comparative Analysis of Cardiac Effects of α<inf>1A</inf>-Adrenoreceptor Stimulation In Vivo and Ex Vivo in Newborn Rats

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. The study examined the effects of α1A-adrenoceptor stimulation on chronotropic function of Langendorff-perfused isolated heart ex vivo and on cardiac chronotropy in vivo in 7-day-old rats. α1A-Adrenergic receptor agonist A-61603 reduced heart chronotropy only in the whole organism. No chronotropic effects of selective stimulation of α1A-adrenergic receptors on isolated hearts were observed in ex vivo experiments. These findings suggest that α1A-adrenergic receptors are not implicated in HR regulation in newborn rats. Bradycardia induced by activation of these receptors in vivo is most likely associated with reflex influences on the heart and changes in the vascular tone in the whole organism

Influence of HCN channels on isolated heart functions in adult rats

Heart pacemaking has triggered a research interest for many decades. Hyperpolarization-activated currents (If) and ion channels (HCN channels) that provide this current are widespread in the central and peripheral nervous system. In atypical cardiomyocytes, HCN channels generate a spontaneous electrical activity. The physiological role of HCN channels in the working myocardium remains a subject of constant research. The expression of HCN channels in cardiomyocytes of the ventricles was shown. It is possible that If participates in the formation of the potential action of working cardiomyocytes and, consequently, in the regulation of the inotropic cardiac function. The study was performed in order to investigate the role of hyperpolarization-activated currents on chronotropy, inotropy, and coronary flow of the Langendorff heart in adult rats. Experiments ex vivo were performed on random-bred albino rats aged 20 weeks. The heart was perfused in the Langendorff System (ADInstruments). The coronary flow, left ventricular pressure, and heart rate were calculated along the curve. 10–9 – 3?10–5 М concentrations range of ZD7288 (Sigma) were used for If blockade. The analysis of the results demonstrated that the left ventricular pressure increased after the blockade of If at the concentration of 10–9 M and decreased with the blocker concentration of 3?10–5 M. The ZD7288 caused bradycardia of the isolated heart at the concentrations of 10–9, 10–6, 3?10–5 M. The isolated heart coronary flow decreased with the blockade of If at the concentration of 10–9 M and 3?10–5 M. It was concluded that If blockade changes chronotropy, inotropy, and coronary flow of the isolated heart in adult rats

The aortic elasticity in hearing-impaired girls after dynamic load

© 2019 by Advance Scientific Research. Persons with hearing impairments are a fairly large group of people whose physiological characteristics are poorly understood. Particular attention should be paid to the state of their cardiovascular system due to the fact that the body of a hearing-impaired person develops in reduced motor activity. When measuring hemodynamic parameters in real-time using an ultrasound monitor in girls with varying degrees of hearing loss, differences were revealed compared with those of normally hearing girls. We analyzed the following hemodynamic parameters at rest and after dynamic loading: aortic compliance (C), mean pressure gradient in aorta (Pmn), pulse arterial pressure (BPp), peak velocity (Vpk), and stroke volume variation (SVV). Higher values of mean pressure gradient in aorta, pulse blood pressure, and peak velocity after dynamic loading were obtained. Differences in the dynamics of aortic compliance indicator values were revealed. An assessment of aortic elasticity in girls with hearing impairment is given. These studies can be used during medical examinations in people with disabilities; when compiling guides for doctors and specialists in cardiology and functional diagnostics; in the preparation of teaching aids for specialists in age and sports physiology, teachers and trainers of specialized boarding schools for hearing-impaired and deaf children

Alpha(1)-adrenoceptors activation decreases myocardial contractility in newborn rats

© 2020, Editorial board of Journal of Experimental Biology and Agricultural Sciences. All rights reserved. Alpha(1)-adrenergic receptors (α1-AR) are found in cardiomyocytes, endothelial cells, and smooth muscle cells of humans and animals. Despite the fact that α1-AR make up 10% of the total number of adrenergic receptors, these receptors also involved in the regulation of inotropic and chronotropic functions of the heart. According to some scientists, the effects of α1-AR activation are not required for the basal contractile function of the heart while other group of researchers believe that α1-AR can be considered as cardioprotective targets; in particular, it is postulated that the α1A-subtype of adrenergic receptors can provide significant inotropic support in cardiac pathologies. This study was carried out on 6-7-day-old outbred newborn rat pups to evaluate the effect of alpha(1)-adrenoceptors activation on the myocardial contractility in newborn rats. For this, Alpha1-adrenergic receptors were stimulated by the pharmacological drug methoxamine at concentrations of 10-9-10-6 mol and the reaction of the contractile force of the strips of myocardium ventricles and heart atria in response to the agonist was investigated. Results of study revealed that stimulation of alpha1-adrenergic receptors, regardless of the methoxamine concentration, led to a negative inotropic reaction of the myocardium of atria and ventricles of newborn rat pups. This study showed unidirectional inotropic responses on rat atrial and ventricular myocardium in response to α1-adrenergic receptors stimulation. Methoxamine smoothly reduces the contractile force of the strips of myocardium atria and ventricles. At the same time, the concentration dependence on the inotropic reaction of the myocardium was observed. Results of study suggested that probably α1-adrenergic receptors along with the main regulators β-adrenergic receptors carry out fine tuning of the heart activity

The heart contractility of hearing-impaired young people under static load

© 2019 by Advance Scientific Research. The contractile function of the heart is controlled by the autonomic nervous system. The reaction of the contractile function of the heart to physical activity clearly demonstrates the features of the regulation of the cardiovascular system. In the modern way of life, the response of the body's systems to static loads is of particular importance. It is necessary to conduct regular diagnostics of the state of the cardiovascular system of hearing-impaired people due to the fact that their body develops under reduced physical activity and is exposed to mainly static loads. Diagnosis of hemodynamic parameters using an ultrasound monitor in young men with varying degrees of hearing loss revealed differences compared with healthy young men. We studied the following hemodynamic parameters at rest and after the static load: stroke volume (SV), cardiac output (CO), stroke work (SW), cardiac power (CPO). Higher values of these indicators were recorded at rest (except for SW) and after the static load. Signs of the predominance of the influence of the sympathetic nervous system on the regulation of hemodynamics in young people with hearing pathology were recorded. The reaction of the contractility of the heart in young people with hearing impairments was evaluated. These studies can be used during medical examinations in people with disabilities; when compiling guides for doctors and specialists in cardiology and functional diagnostics; in the preparation of teaching aids for specialists in age and sports physiology