Problems and prospects for finding new pharmacological agents among adenosine receptor agonists, antagonists, or their allosteric modulators for the treatment of cardiovascular diseases.

A1-adenosine receptors (A1AR) are widely distributed in the human body and mediate many different effects. They are abundantly present in the cardiovascular system, where they control angiogenesis, vascular tone, heart rate, and conduction. This makes the cardiovascular system A1AR an attractive target for the treatment of cardiovascular diseases (CVD). The review summarizes the literature data on the structure and functioning of A1AR, and analyzes their involvement in the formation of myocardial hypertrophy, ischemia-reperfusion damage, various types of heart rhythm disorders, chronic heart failure, and arterial hypertension. Special attention is paid to the role of some allosteric regulators of A1AR as potential agents for the CVD treatment.

The role of iNOS inhibition in the mechanism of the cardioprotective effect of new GABA and glutamic acid derivatives in the model of acute alcoholic myocardial injury in rats.

The cardioprotective effects of new derivatives of glutamic acid (glufimet) and GABA (mefargin) were studied in rats exposed to acute alcohol intoxication (AAI) under conditions of selective blockade of inducible NO-synthase (iNOS). AAI induced a pronounced decrease in the contractile function of the myocardium during exercise tests (load by volume, test for adrenoreactivity, isometric exercise), caused mitochondrial dysfunction and increased processes of lipid peroxidation (LPO) in heart cells. A decrease in NO production during iNOS inhibition and AAI improved the respiratory function of mitochondria, a decreased the level of LPO products, and increased mitochondrial superoxide dismutase activity of heart cells. This led to an increase in myocardial contractility. The studied compounds, glufimet and mefargin, caused a statistically significant increase in the rates of myocardial contraction and relaxation, left ventricular pressure, and also reduced NO production. This was accompanied by a decrease in the intensity of LPO processes and an increase in the respiratory control ratio (RCR), reflecting the coupling between respiration and phosphorylation processes during activation of the respiratory chain complexes I and II. The decrease in NO concentration during selective blockade of iNOS and administration of the studied substances was less pronounced than without blockade of the enzyme. This suggests the putative effect of new derivatives of neuroactive amino acids on the NO system.

Effect of RGPU-260, a Novel GABA Derivative, on Functional Reserves of Rat Heart after Chronic Alcohol Intoxication.

The effect of a new derivative of GABA, the compound RGPU-260, on the heart contractility of rats exposed to chronic alcohol intoxication (10% ethanol solution for 24 weeks) was studied. In comparison with intact rats, the alcoholized ones were characterized with smaller increments in the rates of myocardial contraction (+dP/dtmax) and relaxation (-dP/dtmax), left ventricular pressure, and maximum intensity of functioning of structures during the load tests (volume load/preload, stimulation of the cardiac adrenergic receptors, and occlusion of the ascending aorta/afterload) attesting to degraded cardiac contractility function. In rats treated with RGPU-260 (daily, 25 mg/kg intragastrically during 14 days), these parameters were higher in comparison with control values indicating a positive action of the examined agent on inotropic function of the heart. Effectiveness of cardiotropic action of RGPU-260 was comparable to that of the reference drug mildronate.

Effects of Zoniporide and BMA-1321 Compound on the Rate of Oxygen Absorption by Cardiomyocyte Mitochondria in Rats with Experimental Chronic Heart Failure.

Uncoupling of respiration and ATP production by myocardial mitochondria was observed in rats with chronic isoproterenol intoxication (L-isoproterenol subcutaneously, 1 mg/kg, for 10 days) in comparison with controls (injected with the solvent). Inhibitors of NHE-1 zoniporide (1 mg/kg intraperitoneally, 13 days) and BMA-1321 compound (0.92 mg/kg intraperitoneally, 13 days) improved the mitochondrial function in rats with isoproterenol-induced cardiac failure: respiratory control coefficients increased, more so for the respiratory chain complex II, the main source of ROS in heart failure. The effect of BMA-1321 was more manifest (53%; p<0.05) in comparison with zoniporide (35%; p<0.05).

Correction of Alcohol-Induced Damage to Mitochondria in Cardiac and Cerebral Cells by Derivatives of Neuroactive Amino Acids.

We studied LPO intensity and respiration of mitochondria in brain and heart cells of rats receiving 5% ethanol for 20 weeks and treated with derivatives of neuroactive amino acids. Chronic semicompulsory alcohol intoxication increased the concentration of LPO products in cardiac and cerebral mitochondria by 46 and 45% (diene conjugates), by 97 and 8% (diketones), and by 28 and 81% (malondialdehyde), respectively, reduced activity of antioxidant enzymes in cardiac and cerebral mitochondria by 24 and 45% (glutathione peroxidase) and by 22 and 26% (superoxide dismutase), respectively, and uncoupled the process of respiration and ATP synthesis, which manifested in a decrease in respiratory control (V3/V4 ratio according to Chance). Glutamic acid derivative Neuroglutam (26 mg/kg) and GABA derivative succicard (44 mg/kg) administered intraperitoneally daily for 28 days after termination of alcoholization decreased the levels of primary and secondary LPO products, up-regulated activity of antioxidant enzymes in mitochondria of the heart and brain, and moderated the mitochondrial dysfunction.

Effects of Gaba Derivatives on Anxious and Compulsive Behavior in Offspring of Rats with Experimental Preeclampsia.

We studied the effects of GABA derivatives on anxious and compulsive behavior of progeny of rats with experimental preeclampsia provoked by replacement of drinking water for 1.8% NaCl solution from the first day of pregnancy to delivery. In comparison with progeny of health rats, the offspring of dams with complicated pregnancy demonstrated high level of anxiety and the development of obsessive-compulsive disorder both at the early (40 and 70 days) and late (6 and 12 months) stages of ontogeny. GABA derivatives succicard, salifen, and phenibut reduced symptoms of experimental preeclampsia in offspring of various age by decreasing the level of anxiety and reducing compulsive behavior. The efficacy of the examined derivatives was similar to that of the reference drug Pantogam.

[Age-specific changes in the functional indices of rats' cardiac mitochondria in chronic alcohol intoxication.]

The effect of chromic continuous consumption of 5 and 10% ethyl alcohol over 6 months on the respiratory function and oxidant/antioxidant status of rats' cardiac mitochondria of different gender and age has been studied. A decrease in oxygen consumption rate by cardiomyocyte mitochondria in the metabolic conditions V2, V3, V4 according to Chance involving activation of respiratory chain complexes I, I+II and II in elderly (24-month old) animals as compared to young (11-month old) animals. As the rats were ageing, the concentration of lipid peroxidation (LPO) products (malondialdehyde) was increasing, while the activity of antioxidant enzymes (superoxide dismutase and glutathione peroxidase) was decreasing in cardiomyocyte mitochondria. Chronic alcoholization of 24-month old rats of both genders resulted in a more pronounced decline in the respiratory function activity of cardiac mitochondria, uncoupling of respiration and oxidative phosporylation, reduced activity of antiradical protection enzymes and increased LPO products as compared to younger rats.

Composition and cardioprotective effects of Primula veris L. solid herbal extract in experimental chronic heart failure.

BACKGROUND: High interest in chronic heart failure (CHF) is accounted for by its high incidence, poor prognosis, growing number of hospital admissions due to the heart failure relapse, and inadequate treatment. These facts necessitate a search for new pharmacological agents for the CHF correction. Herbal medicinal products appear to be very promising as they have a noticeable therapeutic effect and tend to be more harmless in comparison to the most of synthesized medications. PURPOSE: Our aim was to study the composition of the Primula veris L. solid herbal extract (PVSHE) and its effects on the myocardial contractile function in animals with experimental CHF. STUDY DESIGN: The study design involved the identification of the raw material composition of the P. veris L. extract. For the experimental part of our research, we used the model of CHF to elucidate the cardioprotective properties of PVSHE. METHODS: The active extract constituents were isolated by thin-layer chromatography and column chromatography; the extract components were identified by high-performance liquid chromatography, ultraviolet spectroscopy (UVS), and nuclear magnetic resonance spectroscopy (NMRS). To model CHF, L-isoproterenol at a dose of 2.5 mg/kg was intraperitoneally injected to the experimental rats twice a day for 21 days. Cardiac output was assessed with the loading test, adrenoreactivity test, and maximum isometric loading test; CHF markers adrenomedullin and copeptin were detected in blood plasma with ELISA kit for adrenomedullin and copeptin (Coud-Clone Corp., USA). RESULTS: P. veris L. solid herbal extract contains flavonoid aglycons (apigenin, quercetine, kaemferol), flavonoid glycosides (cinarozid, rutin, hyperozid), as well as polymethoxylated flavonoids acting as chemotaxonomic markers for the genus Primula (8-methoxy-flavone; 3',4'methylenedioxy-5'-methoxyflavone). The substance 3',4'methylenedioxy-5'-methoxyflavone has been isolated from the primrose herb for the first time. We showed that the PVSHE has a cardioprotective effect when it was administered at a dose of 30 mg/kg in the experimental CHF, as evidenced by a lower number of animal death, lower level of CHF markers in the blood plasma of the experimental animals, the higher increase in rate of myocardial contraction and relaxation, the higher level of left ventricular pressure (LVP) and of maximum intensity of structural performance (MISP), as compared to the control group. CONCLUSION: P. veris L. solid herbal extract contains flavonoid aglycons, flavonoid glycosides, and polymethoxylated flavonoids. The herbal agent increases the myocardial contractility in experimental CHF.

[Influence of the dense extract from herb of Primula veris L. On the oxidative stress development and the functional state of the cardiomyocytes mitochondria of rats with experimental chronic heart failure]. / Vliianie gustogo ékstrakta iz travy pervotsveta vesennego na razvitie oksidativnogo stressa i funktsional'noe sostoianie mitokhondrii kardiomiotsitov krys s éksperimental'noi khronicheskoi serdechnoi nedostatochnost'iu.

Experimental chronic heart failure (CHF), caused by administration of L-isoproterenol (2.5 mg/kg twice a day intraperitoneally for 21 days), promotes uncoupling of respiration and oxidative phosphorylation. The rate of mitochondrial oxygen consumption in the metabolic state V3 by Chance in animals with CHF decreased by 53.3% (p<0.05) with malate using (as an oxidation substrate feeding сomplex I of the electron transport chain (ETC)), by 70.6% (p<0.05) with succinate using (сomplex II substrate) and by 63.6% (p<0.05) when malate and succinate were added simultaneously. The respiratory control ratio significantly decreased 2.3 times for сomplex I, 2.5 for сomplex II, and 2.6 times for the simultaneous operation of two respiratory chain complexes in mitochondria of CHF rats compared to intact animals. Mitochondrial dysfunction in experimental CHF is evidently due to the development of oxidative stress. It was revealed that the content of malonic dialdehyde (MDA) in the group of rats with experimental CHF was higher by 54.7% (p<0.05), as compared with intact animals. The activity of superoxide dismutase (SOD) and catalase was lower by 17.5% (p<0.05), and by 18.4%, respectively than in the intact group. The dense extract from herba of Primula veris L. (DEHPV) 30 mg/kg limits the development of mitochondrial dysfunction in rats with experimental CHF, as evidenced by an increase in the role of V3 respiration for the first and second respiratory chain complexes in 1.7 (p<0.05) and 2.0 times (p<0.05), respectively, the ratio of respiratory control (RCR) - 1.7 times (p<0.05) for сomplex I and 2 times (p<0.05) for сomplex II compared with the negative control. The concentration of MDA was by 15.7% (p<0.05), lower and the activity of SOD was by 56.3% (p<0.05) higher.

Evaluation of DNA Damage in Experimental Preeclampsia by Comet Assay.

Experimental preeclampsia induced by substitution of drinking water with 1.8% NaCl during pregnancy was associated with an increase in the level of DNA damage in fetal brain and placenta measured by DNA comet assay by 35.7 and 27.8 times, respectively, in comparison with physiological pregnancy.

Inhibition of the Expression of Inducible NO Synthase by Neuroactive Amino Acid Derivatives Phenibut and Glufimet In Vitro and Ex Vivo.

The effects of glufimet and phenibut (glutamic acid and GABA derivatives, respectively) on concentration of inducible NO synthase and cGMP in LPS-activated mouse peritoneal macrophages and on NO end products in their culture medium were examined in vitro and ex vivo. Addition of LPS into culture medium elevated concentration of NO metabolites in this medium and increased concentration of inducible NO synthase and cGMP in the lysates of peritoneal macrophages, whereas incubation of the cells with examined agents applied at concentration of 10-5 M diminished these indices. Similar results were obtained with intraperitoneal injection of LPS, glufimet, and phenibut. In culture medium containing peritoneal macrophages from the mice injected with LPS (100 µg/kg), the concentrations of inducible NO synthase and cGMP as well as the total concentration of nitrite and nitrate ions increased, whereas in culture medium with the cells from LPS-exposed mice treated with glufimet (28.7 mg/kg) and phenibut (50 mg/kg) these indices significantly decreased.

Effect of Phenibut and Glufimet, a Novel Glutamic Acid Derivative, on Respiration of Heart and Brain Mitochondria from Animals Exposed to Stress against the Background of Inducible NO-Synthase Blockade.

Increased oxygen consumption by heart and brain mitochondria in the absence of ADP and reduced mitochondrial respiration in the presence of ADP were observed in rats exposed to stress simulated by suspension by the dorsal neck skin fold for 24 h, which attests to uncoupling of substrate oxidation and ATP synthesis and can cause electron drain from the respiratory chain, formation of ROS, and oxidative damage to cell structures. Blockade of inducible NO synthase with aminoguanidine (single intraperitoneal dose of 50 mg/kg before stress exposure) increased coupling of respiration and oxidative phosphorylation in heart and brain mitochondria of rats exposed to immobilization-painful stress, which was especially pronounced in cardiomyocytes. The test compounds glufimet (single intraperitoneal dose of 29 mg/kg before stress exposure) and phenibut (single intraperitoneal dose of 50 mg/kg before stress exposure) limited stress-induced mitochondrial damage against the background of inducible NO synthase blockade and without it, which was seen from increased respiratory control ratio in comparison with that in untreated rats exposed to stress (control).

[Protective effects of a new glutamic acid derivative against stress after nNOS blockade]. / Stressprotektornoe deistvie novogo proizvodnogo glutaminovoi kisloty pri blokade neironal'noi NO-sintazy.

We studied the effects of a new glutamic acid derivative, glufimet, on oxidative stress, activity of antioxidant enzymes, mitochondrial respiration, endothelial vasodilation and anti-platelet activity in female rats after exposure to 24-hour immobilization pain stress and 7-nitroindazole, a neuronal nitric oxide synthase (nNOS) inhibitor. A single dose administration of glufimet (29 mg/kg intraperitoneally) 10 minutes before stress exposure caused a decrease of NO metabolites in serum (by 27.2%) and heart homogenate (33.5% (p£0.05), respectively, compared with the control group. Administration of 7-nitroindazole with glufimet also decreased the studied parameters by 14.3% in the heart homogenate and by 30,3% in the brain (p£0.05) compared with stress exposed rats receiving only the nNOS inhibitor. Glufimet decreased the levels of primary and secondary products of lipid peroxidation (LPO), conjugated dienes by 20% (p£0.05) and 17.3% (p£0.05), ketodienes by 16% and 13.7%, malondialdehyde by 15% (p£0.05) and 26.6% (p£0.05) in the heart and brain mitochondria of stress exposed rats, respectively, compared with the control group. Glufimet administration also increased SOD activity (by 14.4% and 13.1%, respectively), catalase (by 19% and 26.8%, respectively) and glutathione peroxidase (GPx) activity (by 45.5% (p£0.05) and 7.3%, respectively). The antioxidant effect of glufimet may be also attributed to increased coupling between the processes of mitochondria respiration and oxidative phosphorylation. This was evidenced by an increase in the respiratory control ratio (RCR) (by 46.0% (p£0.05) for malate/glutamate and by 49,7% (p£0.05) for succinate) in the heart mitochondria. A statistically significant increase in RCR (by 37.3% (p£0.05)) was observed in stress exposed female rat brain mitochondria for succinate. RCRs differed significantly for succinate in the heart and brain of rats receiving glufimet after nNOS blockade. RCR increased by 62.3% (p£0.05) in the heart mitochondria and by 72.2% (p£0.05) in the brain mitochondria compared with the RCRs in stress exposed rats receiving 7-nitroindazole.

Features of endothelial dysfunction and morphofunctional changes of the uteroplacental complex in experimentally induced pre-eclampsia.

BACKGROUND: Pre-eclampsia is considered to be a severe complication of pregnancy. Theoretical investigation of its etiology and pathogenesis, development of strategies for its prevention and treatment are conditioned by the development of appropriate experimental models of this pathology. METHODS: The study involved Wistar rat lines weighing 220-240g. Experimental pre-eclampsia was modeled by replacing drinking water consumed by pregnant female rats with 1.8% NaCl solution throughout gestation. Arterial pressure, protein concentration in urine and tissue hydration extent were measured on the 1st and 21st days of gestation. Uteroplacental blood flow, vasodilating and antithrombotic endothelial functions were also assessed. For pathomorphological and immunohistochemical investigation murine monoclonal antibodies against vascular endothelial growth factor (VEGF), polyclonal rabbit antibodies against inducible and endothelial NO-synthases were used. RESULTS: Replacing drinking water with 1.8% NaCl solution in female rats throughout gestation elevates arterial pressure, causes proteinuria and edema, impairs vasodilating and antithrombotic endothelial properties, and suppresses uteroplacental blood circulation. A morphological examination of the animals revealed the signs of focal duodenitis, spasms of myometrium arteries with no invasion of syncytiotrophoblast into its walls which also involved a raised VEGF and reduced eNOS expression in the endothelium of myometrial vessels, as well as cytoplasmic expression of iNOS in the cells of inflammatory infiltrate. CONCLUSIONS: These findings make it possible to conclude that replacing drinking water with 1.8% NaCl solution causes a number of changes typical of pre-eclampsia and, therefore, can be regarded as an experimental model of this pathologic condition.

[The effect of sulodexide on placental mitochondria function in rats with experimental preeclampsia]. / Vliianie sulodeksida na funktsional'noe sostoianie mitokhondrii platsenty samok krys s éksperimental'noi preéklampsiei.

Substitution of drinking water for 1.8% NaCl in pregnant rats caused a pronounced increase in arterial pressure by 24,3% and urinary protein by 117% to day 21 of pregnancy. State 4 respiration of isolated placental mitochondria in the group of negative control was 3- and 1.5-fold higher with malate/glutamate and succinate as substrates than in placental mitochondria isolated from uncomplicated pregnant animals. This led to a decrease of the respiratory control ratio. These results suggest that development of experimental preeclampsia is accompanied by mitochondrial dysfunction through uncoupling of oxidative phosphorylation. Daily administration of sulodexide to females with experimental preeclampsia (EP) per os at a dose of 30 LE during the whole period of gestation decreased manifestations of the disease as evidenced by a slight increase in blood pressure (by 8,6%) and less pronounces increase in urinary protein (by 58,9%). Sulodexide decreased development of mitochondrial dysfunction in EP rats as shown a decrease of non-stimulated ADP respiration with malate/glutamate and succinate (4.5- and 2.5-fold, respectively) as compared with the negative control group and the corresponding increase in the respiratory control ratio (2.5- and 1.5-fold, respectively). Thus, sulodexide reduces uncoupling of oxidative phosphorylation and enhances the functional activity of mitochondria in EP animals, possibly due to its antioxidant and endotelioprotective effects.

Spatial Memory in the Progeny of Rats Subjected to Different Types of Experimental Preeclampsia.

Spatial memory was studied in 2-month-old offspring of rats subjected to different types of experimental preeclampsia (replacement of drinking water with 1.8% NaCl from day 1 to 21 of gestation or intraperitoneal administration of non-selective NO-synthase inhibitor L-NAME to pregnant rats in a daily dose of 25 mg/kg for 7 days on gestation days 14-20). Spatial memory was evaluated in an elevated 8-arm radial maze. Both types of experimental preeclampsia impaired spatial (long-term and short-term) memory and can be used in the development of drugs correcting negative effects of this pregnancy complication on memory.

[Glutamate Metabotropic Receptors: Structure, Localisation, Functions].

The data on the structure, location and functions of the metabotropic glutamate receptor is shown. The family consists of 8 mGluRs subtypes and is divided into three groups: I group--mGluRs1/mGluRs5, II group--mGluRs2/mGluRs3, III group--mGluRs4/mGluRs6/mGluRs7/mGluRs8. They are associated with G-protein; signaling in the cells is carried out by IP3 or adenylate cyclase signaling pathways, in the result of which, mGluRs modify glial and neuronal excitability. Receptors are localized in the CNS and periphery in non-neuronal tissues: bone, heart, kidney, pancreas pod and platelets, the gastrointestinal tract, immune system. Their participation in the mechanisms of neurodegenerative diseases, mental and cognitive disorders, autoimmune processes, etc. is displayed. Agonists, antagonists, allosteric modulators of mGluRs are considered as potential medicines for treatment of mental diseases, including depression, fragile X syndrome, anxiety, obsessive-compulsive disorders, Parkinson's disease, etc.

[Glutamate lonotropic Receptors: Structure, Localisation, Function].

The data on the structure, location and function of ionotropic glutamate receptors is shown. These include NMDA-, AMPA-, kainate and orphan receptor, activation them ensures the formation of an action potential. The ionotropic receptors are present in the CNS and peripheral organs. There are a large number of them allosteric modulators, agonists and antagonists. NMDA- and AMPA-receptors play a key role in the origin and manifestation of long-term potentiation. When NMDA- and AMPA-receptors are hyperactivity excitotoxicity arises--a pathological process that causes damage and death of neurons. The ionotropic glutamate receptors are involved in the regulation of mental functions, respiratory, sensory, cardiovascular, nociceptive, etc. g. systems.

[Cardioprotective effect of the new derivative of glutamic acid - glufimet in acute immobilization-painful stress in animals of different ages].

The effect of the 24-hour immobilization-painful stress on myocardial contractility of young (6-month), middle-aged (12-month) and old (24-month) female rats was studied. It was identified a reduction of the functional reserve of the heart, which showed a smaller growth rates of contraction and relaxation of the myocardium (+ dP/dt max and -dP/dt max), left ventricular pressure (LVP) and the maximum intensity of the functioning of the structures (MIFS) under increased pre- afterload and adrenergic stimulation of the heart, especially pronounced in the group of 24-month old rats. The animals of all ages treated before and after stressing glufimet in a dose 29 mg/kg, have higher rates of growth + dP/dt max, -dP/dt max, LVP and MIFS during load tests, most significant rates of growth are noticed in older rats compared with the young and middle-aged. Phenibut improves studied parameters equally at 6, 12 and 24-month old females, subjected to stress.

[CHANGES OF THE OXIDATIVE STATUS, MITOCHONDRIAL FUNCTION, BLOOD PRESSURE AND INDICATORS OF HEMOSTASIS IN STRESSED ANIMALS AND IN THE CONDITIONS OF NO-SYNTHASE BLOCKADE].

Changes in the metabolism of female rats hanging by cervical dorsal skin fold within 24 hours were examined. It was found that stress exposure results in an increase of the concentration of the final nitric oxide metabolites in the blood serum and homogenates of the heart and brain of animals, intensification of processes peroxidation lipids and mitochondrial dysfunction in these organs. Thus increase of mean arterial blood pressure by 18.9 % from baseline and violation of platelet and plasma components of hemostasis. Inhibitor of neuronal NO-synthase 7-nitroindazole in the dose of 50 mg/kg aggravates of the studied parameters changes. Administration of an animal selective inhibitor of inducible NOS aminoguanidine (50 mg / kg) contributes to limiting the damaging effects of stress reaction.