Correlation of the Left Ventricular Systolic Dysfunction and Ventricular Depolarization in a Post-Infarction Model of Chronic Heart Failure.

The body surface potential mapping of the heart during the period of ventricular depolarization and the inotropic function of the ventricles were studied in rats under conditions of a translational model of post-infarction chronic heart failure developed by us. We revealed a statistically significant (p<0.001) correlation between the left-ventricular ejection fraction and the values of the maximum positive and negative extrema of the cardioelectric field on the body surface of rats with post-infarction chronic heart failure caused by anterior transmural myocardial infarction. The calculated linear regression equations have high predictive efficiency, which makes it possible to use the amplitude characteristics of the heart cardioelectric field as a marker of the development of chronic heart failure.

Changes in Microcirculation in the Brain, Heart, and Liver in Female Rats with Translational Model of Alcoholic Cardiomyopathy.

We studied some features of blood and lymph microcirculation in the brain, heart, and liver of female rats with developed alcoholic cardiomyopathy. In female rats after 24-week forced consumption of 10% ethanol solution, the size and inotropic function of the heart were measured by echocardiography. Microcirculation in the brain, myocardium, and liver was assessed by laser Doppler flowmetry using LAKK-OP2 and LAZMA-D computerized laser analyzers. Using spectral wavelet analysis, we determined the absolute and normalized to total perfusion amplitudes of microcirculation oscillations reflecting various regulatory mechanisms. Intact animals served as controls. In rats of the experimental group, alcoholic cardiomyopathy completely developed. Under these conditions, the index of microcirculation in the brain, myocardium, and liver significantly decreased. At the same time, there was a redistribution in the brain between shunting and nutritive blood flow in favor of the latter. In the myocardium and liver, this ratio did not change.

Cardioprotective Effects of Metalloproteinase Inhibitor 1-({4-[(4-Chlorobenzoyl)amino]phenyl}sulfonyl-L-Proline in Modeled Acute Myocardial Infarction.

Cardioprotective effect of 1-({4 [(4 chlorobenzoyl)amino]phenyl}sulfonyl-L-proline (compound AL-828) was studied in rats with modeled acute myocardial infarction. The test compound was administered intragastrically in a dose of 30 mg/kg/day for 3 days prior to infarction modeling. Metalloproteinase inhibitor antibiotic doxycycline served as the reference drug and was administered in a dose of 40 mg/kg/day by the same schedule. It was shown that AL-828 similar to doxycycline significantly reduced the intensity of myocardial remodeling and maintained the inotropic function of the myocardium in the acute phase of myocardial infarction. By the 20th minute of ischemia, the end-systolic dimension of the left ventricle in control animals increased from 1.98±0.12 to 3.84±0.16 mm, while in animals treated with AL-828, this increase was significantly (p=0.007) less pronounced (from 1.84±0.07 and 2.87±0.21 mm, respectively). The ejection fraction characterizing the inotropic status of the left ventricle in animals treated with AL-828 was significantly higher (p=0.02). By its cardioprotective activity, AL-828 was not inferior to the reference drug doxycycline. It can be assumed that the cardioprotective activity of compound AL-828 is related to suppression of MMP-9 expression and/or inhibition of its activity as was previously demonstrated by us.

Examination of Cardioprotective Effects of Fabomotizole Hydrochloride in Translational Rat Model of Chronic Heart Failure.

A translational rat model of chronic heart failure was employed to examine the cardioprotective effect of fabomotizole hydrochloride. Fabomotizole therapy for 28 days (15 mg/kg/day intraperitoneally) restored inotropic function of the left ventricle and increased ejection fraction from 54±3 to 65±3% (p=0.001). The inotropic function returned to normal against the background of significantly reduced myocardial expression of angiotensin (p=0.01) and glucocorticoid (p=0.03) receptors and significant increased expression of sigma-1 receptors (p=0.04). Inhibition of abnormal expression of angiotensin and glucocorticoid receptors responsible for activation of the pathological cascades underlying the postinfarction remodeling of the left ventricle as well as activation of the expression of cytoprotective sigma-1 receptors are viewed as the key features of the cardioprotective action of fabomotizole hydrochloride.

A Translational Model of Chronic Heart Failure.

We created a translational model of chronic heart failure in rats that developed in 3 months after reproducing experimental anterior transmural myocardial infarction. The model simulated the basic clinicodiagnostic criteria of this disease: impaired contractility and dilatation of heart ventricles, signs of venous congestion, elevated plasma content of biochemical markers, and abnormal overexpression of AT1aR and ß-adrenoceptors.

On the Mechanism of the Cardioprotective Action of σ1 Receptor Agonist Anxiolytic Fabomotizole Hydrochloride (Afobazole).

Original translational rat model of chronic heart failure provoked by experimental anterior transmural myocardium infarction was employed to examine the preventive action of anxiolytic Afobazole (15 mg/kg/day administered intraperitoneally during the first 15 days after coronary occlusion) on the development of the heart failure assessed in 3 months after infarction. Afobazole prevented the development of pathologic remodeling of the myocardium, maintained its inotropic function, and decreased the plasma level of brain natriuretic peptide known as a biochemical marker of chronic heart failure. In the myocardium, Afobazole down-regulated overexpression of the genes induced in chronic heart failure and assessed by corresponding RNA levels, which code angiotensin (AT1A-R), vasopressin (V1A-R), and glucocorticoid (GR) receptors as well as Epac2 protein. The revealed biochemical changes are consistent with the data on cardioprotective action of Afobazole.

Alcoholic Cardiomyopathy: Translation Model.

We developed a translation model of alcoholic cardiomyopathy in rats. By the end of forced alcoholization (the rats received 10% ethanol solution as the only source of fluid for 24 weeks; mean daily ethanol consumption was 5.0-6.5 g/kg), the rats developed dilated heart failure. Echocardiography and morphometric study of the myocardium revealed a decrease in inotropic function of the heart and dilatation of the right and left ventricles. Fatty degeneration of the myocardium (pathognomonic sign of alcoholic cardiomyopathy) and decrease in electrical stability of cardiomyocytes reliably reproduce the clinical pattern of alcoholic cardiomyopathy.

Delayed Results of Experimental Afobazole Therapy in Rats after Acute Myocardial Infarction.

Delayed cardioprotective effects of anxiolytic Afobazole (15 mg/kg, intraperitoneally for 14 days) were evaluated using dynamic echocardiographic recordings on days 2, 15, 56, and 98 after experimental myocardial infarction modeling (rat model of acute myocardial ischemia). The cardiotropic activity of Afobazole is assumed to be related to its agonistic effects on σ1 receptor of cardiomyocytes. It was found that animals treated with Afobazole had no signs of heart failure by the end of observation, as evidenced by left ventricular ejection fraction.

Evidence of Echocardiography Validity in Model Experiments on Small Animals.

Dynamic echocardiographic monitoring in rats subjected to forced alcoholization showed the formation of disorders in intracardiac hemodynamics characteristic of ethanol cardiomyopathy formed by the end of 24-week continuous ethanol consumption. The results of echocardiographic monitoring were confirmed by histological and morphometric studies demonstrating fatty infiltration of the myocardium pathognomonic for this condition and bifocal dilatation of cardiac ventricles. These results persuasively demonstrate that echocardiographic studies on small animals are valid and can be used for search for cardiotropic drugs and studies of the mechanisms of their activities.

[To the potential use of alcoholic cardiomyopathy echocardiography assessment of forming].

Chronic alcohol abuse leads not only to a significant human psychic and social degradation, but also promotes the alcoholic cardiomyopathy formation, that is one of the leading causes of high mortality of alcoholics. However, to date in clinic there are no unified approaches in the prevention and treatment of alcoholic cardiomyopathy, first of all, due to the lack of the adequate model in the experimental pharmacology, which can assess the stages of formation of alcoholic cardiomyopathy objective and in real time, and thus create the basis for the search and study the mechanisms of action of drugs for the treatment of this serious disease. Studing the possibility of echocardiography using in experiments with rats exposed to prolonged forced alcoholism is one of the approaches to solve this problem. It was shown that the significant changes of intracardiac echocardiography hemodynamics corresponding to the known from the clinic, begining to form from the 20th week of systematic consumption of alcohol by rats. At this time interval the reduction in inotropic function of the heart in alcoholized rats compared to control is observed: fraction shortening (FS) is 41.9% (40.3-42.2) and 51.3% (48.8-59.1) respectively, and ejection fraction (EF) 78.8 (77.4-79.2) and 87.5% (84.6-92.4) respectively, p = 0.0215. The dilated heart failure develops in the rats from the 24 week of regular alcohol consumption, as evidenced not only by dynamic reducing of FS and FV, but also by the dilatation ofthe heart. For example, the end-systolic size of the left ventricle in animals consuming alcohol compared with control increased more than 2 times (4.31 mm (3.80-4.41) and 2.0 mm (1.85-2.36); p = 0.0008, and the end-diastolic dimension was 5.95 mm (5.13-6.37) and 4.52 mm (3.85-4.90) respectively; p = 0.0171. Thus, the echocardiographic picture characteristic for alcoholic dilated cardiomyopathy is formed by the end of the 24th week of chronic alcoholiation.

Effect of metalloproteinase inhibitor on early postinfarction remodeling in the most acute phase of myocardial infarction.

Echocardiography in control narcotized rats (n=12) revealed that acute single-stage ligation of coronary artery induced a rapid and significant decrease in systolic function of the heart, which attained minimum to postischemic minutes 10-20 and then gradually restored during 60 min after coronary occlusion. Matrix proteinase inhibitor doxycycline (40 mg/kg/day intragastrically for 3 days prior to the experiment) prevented dramatic impairment of systolic function in the left ventricle during first 20 min of ischemia and then all the indices characterizing the state of pumping function of the left ventricle in the experimental (doxycycline) group (n=9) surpassed the control. Thus, matrix proteinase inhibitor doxycycline prevented early postischemic remodeling of the heart during the most acute phase of experimental myocardial infarction.

[Peculiarities of myocardial remodeling in the acutest phase of experimental myocardial infarction in rats].

Features of early postischemic cardiac remodeling is well studied both in the clinic and in the experiment. However, the data for this process in the first 60 minutes after occlusion of the coronary vessel in the literature are absent practically. In experiments in rats in which acute myocardial ischemia was reproduced by the simultaneous ligation of the left coronary artery, with the help of echocardiography it is shown that in the first minutes of ischemia in left ventricular systolic function of the heart sharp drops: so, at the 20th minute of ejection fraction (EF) is reduced up 84.5 (79.3-89.2) to 51.7 (50.2-54.4)% - P < 0.05; fraction shortening (FS) is decreased up 52.6 (47.8-59 and 3) to 26.5 (25.9-28.1)% - P < 0.05; a end-systolic dimension (ESD) of the left ventricle is increased up 1.90 (1.70-2.26) to 3.80 (3.50-4.10) mm - P < 0.05, whereas the sham animals were not observed any statistically significant violations of left ventricular systolic function during the observation period (60 minutes). In the period up 20 to 60 min of ischemia is noted a gradual improvement of the relative systolic heart function. At the 60th minute of ischemia all recorded echocardiographic parameters were significantly (P < 0.05) different from those reported in the period from 10 to 20 min of ischemia - EF 62.4 (59.0-64.3)%, FS 33, 7 (31.1-35.2)%, ESD 3.10 (2.80-3.40) mm, etc. Analysis of the results suggests that noted in our experiments the maximum reduction in left ventricular ejection time coincides with the peak of arrhythmogenesis, i.e. with a maximum risk of sudden cardiac death.