Nevena Jeremic

The effects of glycine, glutamate and their combination on cardiodynamics, coronary flow and oxidative stress in isolated rat hearts

Objectives: To examine the effects of glycine, glutamate and their combination on cardiac function, coronary flow and oxidative stress in isolated rat hearts, and to examine the effects of potential activation of N-methyl-Daspartate (NMDA) receptors in isolated rat hearts. Methods: The hearts of male Wistar albino rats were excised and perfused according to the Langendorff technique, and cardiodynamic parameters (maximum rate of pressure development in the left ventricle [dp/dt max]; minimum rate of pressure development in the left ventricle [dp/dt min], systolic left ventricular pressure, diastolic left ventricular pressure, heart rate) and coronary flow were determined during the subsequent administration of glycine, glutamate and their combination. Oxidative stress biomarkers, including thiobarbituric acid-reactive substances, nitrites (NO2 −), superoxide anion radical (O2 −) and hydrogen peroxide (H2O2), were each determined spectrophotometrically in coronary venous effluent. Results: Treatment with glycine and glutamate alone did not cause a statistically significant change in any of the observed parameters; however, their combined administration induced significant decreases in dp/dt max, dp/dt min, heart rate and coronary flow compared with the control conditions. Treatment with glycine and glutamate together induced significant increases in NO2 −, O2 − and H2O2 levels. After the washout period, all parameters that had changed (cardiodynamic parameters, coronary flow and levels oxidative stress biomarkers) returned to values that were not significantly different from controls. Conclusions: The results of the present study indicate that NMDA receptors likely have important roles in the function of the heart and coronary circulation. In addition, these results are suggestive of a damaging effect of NMDA receptor overstimulation in heart functioning, potentially mediated by oxidative stress.

Effects of ischemia and omeprazole preconditioning on functional recovery of isolated rat heart

Objective The aim of this study was to compare protective effects of ischemic and potential protective effects of pharmacological preconditioning with omeprazole on isolated rat heart subjected to ischemia/reperfusion. Methods The hearts of male Wistar albino rats were excised and perfused on a Langendorff apparatus. In control group (CG) after stabilization period, hearts were subjected to global ischemia (perfusion was totally stopped) for 20 minutes and 30 minutes of reperfusion. Hearts of group II (IPC) were submitted to ischemic preconditioning lasting 5 minutes before 20 minutes of ischemia and 30 minutes of reperfusion. In third group (OPC) hearts first underwent preconditioning lasting 5 minutes with 100μM omeprazole, and then submitted 20 minutes of ischemia and 30 minutes of reperfusion. Results Administration of omeprazole before ischemia induction had protective effect on myocardium function recovery especially regarding to values of systolic left ventricular pressure and dp/dt max. Also our findings are that values of coronary flow did not change between OPC and IPC groups in last point of reperfusion. Conclusion Based on our results it seems that ischemic preconditioning could be used as first window of protection after ischemic injury especially because all investigated parameters showed continuous trend of recovery of myocardial function. On the other hand, preconditioning with omeprazole induced sudden trend of recovery with positive myocardium protection, although less effective than results obtained with ischemic preconditioning not withstand, we must consider that omeprazole may be used in many clinical circumstances where direct coronary clamping for ischemic preconditioning is not possible.

The effects of verapamil and its combinations with glutamate and glycine on cardiodynamics, coronary flow and oxidative stress in isolated rat heart

The role of N-methyl-D-aspartate receptor (NMDA-R) in heart is still unclear. For these ionotropic glutamate receptors is characteristic the necessity of both co-agonists, glutamate and glycine, for their activation, which primarily allows influx of calcium. The aim of the present study was to examine the effects of verapamil, as a calcium channel blocker, alone and its combination with glycine and/or glutamate on cardiac function, coronary flow, and oxidative stress in isolated rat heart or to examine the effects of potential activation of NMDA-R in isolated rat heart. The hearts of male Wistar albino rats were excised and perfused according to Langendorff technique, and cardiodynamic parameters and coronary flow were determined during the administration of verapamil and its combinations with glutamate and/or glycine. The oxidative stress biomarkers, including thiobarbituric acid-reactive substances, nitrites, superoxide anion radical, and hydrogen peroxide, were each determined spectrophotometrically from coronary venous effluent. The greatest decline in parameters of cardiac contractility and systolic pressure was in the group that was treated with verapamil only, while minimal changes were observed in group treated with all three tested substances. Also, the largest changes in coronary flow were in the group treated only with verapamil, and at least in the group that received all three tested substances, as well as the largest increase in oxidative stress parameters. Based on the obtained results, it can be concluded that NMDA-R activation allows sufficient influx of calcium to increase myocardial contractility and systolic pressure, as well as short-term increase of oxidative stress.

Ablation of Toll-like Receptor 4 Mitigates Cardiac Mitochondrial Dysfunction in Hyperhomocysteinemia.

Hyperhomocysteinemia (HHcy) is a risk factor for adverse cardiovascular events; however, the mechanism for development of this disease is still unknown. Toll-like receptor 4 (TRL4) is a molecule involved in the immune response pathway and is quickly becoming a receptor of interest in the field of hypertension. In this study, we hypothesized that ablation of TLR4 mitigates cardiac mitochondrial dysfunction in a model of HHcy. Five strains of mice (C57BL/6J, CBS+/-, C3H, CBS+/-/C3H, and C3H/HeOuJ) 10-12 weeks old were utilized. We found that HHcy causes heart hypertrophy and promotes oxidative stress while mice with HHcy and inactivated TLR4 showed significant improvement in examined parameters. A dominance of endothelial cell mitochondrial fission over mitochondrial fusion in HHcy and oxidative stress was observed, which may explain the endothelial cell loss and dysfunction that contributes to inward cardiac remodeling.

MODULATION OF N-METHYL-D-ASPARTATE RECEPTORS IN ISOLATED RAT HEART

Considering the limited data on the role of NMDA-Rs in the cardiovascular system, the aim of the present study was to examine the effects of NMDA and DL-Hcy TLHC, alone and in combination with glycine, memantine, and ifenprodil, in the isolated rat heart. The hearts of Wistar albino rats were retrogradely perfused according to the Langendorff technique at a constant perfusion pressure. The experimental protocol for all experimental groups included the stabilization period, application of estimated substance for 5 min, followed by a washout period of 10 min. Using a sensor placed in the left ventricle, we registered the following parameters of myocardial function: dp/dtmax, dp/dtmin, SLVP, DVLP, HR; CF was measured using flowmetry). We estimated the following oxidative stress biomarkers in the coronary venous effluent using spectrophotometry: TBARS, NO2-, O2-, and H2O2. NMDA alone did not induce any change in any of the observed parameters, while DL-Hcy TLHC alone, as well as a combined application of NMDA and DL-Hcy TLHC with glycine, induced a reduction of most cardiodynamic parameters. Memantine and ifenprodil induced a reduction of cardiodynamic parameters and CF, as well as some oxidative stress biomarkers.

Redox Status in Patients with Femoral Neck Fractures

Abstract The femur transfers the body weight from the pelvic bone to the shinbone. Femur fractures are a significant cause of morbidity and mortality among the group of locomotor apparatus injuries, especially in the elderly population. Considering that oxidative stress occurs as a result of increased production of free radicals that damage cell function and cause numerous pathological conditions and diseases, the aim of this study was to investigate oxidative stress parameters in older patients with femoral neck fractures. This clinical study included 70 patients, of which 35 had femoral neck fractures (26 males and 9 females), while the other half of the patients formed the matched control group. Markers of oxidative stress (NO2−, TBARS, H2O2 and O2-) and anti-oxidative enzymes (SOD, CAT, and GSH) were measured. Results showed that the levels of O2- increased, while levels of NO2-, H2O2 and all the antioxidative enzymes decreased in patients with femoral neck fractures. These findings indicate that fractures cause oxidative stress, probably because of the reduced activity of osteoblasts and the increased activity of osteoclasts.

Impact of hyperbaric oxygenation on oxidative stress in diabetic patients

Taking into consideration that a high concentration of oxygen can express toxic effects due to production of reactive oxygen species (ROS), the aim of our investigation was to establish the influence of hyperbaric oxygenation on oxidative stress parameters and antioxidant enzymes in patients with diabetes mellitus (DM) type 2. Investigation included 50 patients with DM type 2 divided into two groups. The first group consisted of 25 patients, mean age 70 years, mean duration of illness 12 years and without manifest peripheral vascular complications (Wagner 0). The second group consisted of 25 patients, mean age 74 years, mean duration of illness 17 years and with manifest peripheral vascular complications (Wagner 1-5). All patients underwent the same therapeutic protocol, which included 10 hyperbaric oxygenation therapies, once a day for a duration of 60 minutes, with an average partial oxygen pressure of 1.7 atmospheres absolute (ATA). In blood samples the following parameters of redox balance were determined: levels of nitrites (NO₂-), index of lipid peroxidation (TBARS), superoxide anion radical (O₂-), hydrogen peroxide (H₂O₂) and antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). Our results clearly show that hyperbaric oxygen (HBO₂) therapy does not have a pro-oxidative effect. Additionally, it seems that this procedure strongly mobilized the antioxidant enzyme system, thus improving defense from oxidative damage. All significant data are marked as P ⟨0.05. Our results have shown that in terms of ROS production, HBO₂ can be safe to use in patients suffering from DM type 2 with or without vascular complications.

Oxidative Stress Parameters after Abdominal Hysterectomy and their Relationships with Quality of Recovery

Abstract Study aimed to investigate relationship between oxidative stress markers and postoperative recovery in woman after abdominal hysterectomy, as well as to test the hypothesis that different analgesics differently influence redox status. The quality of recovery was evaluated with a QoR-40 questionnaire in fifty-one patients who underwent abdominal hysterectomy, preoperatively and on the 1st, 2nd, 3rd postoperative days (POD1,2,3). Blood samples were collected at baseline (T0), 3 (T1), 24 (T2), 48 (T3) and 72 (T4) hours after surgery. Oxidative stress markers concentrations (TBARS, NO2−, H2O2, O2− ) as well as antioxidative enzymes (SOD, CAT, and GSH) were analyzed. QoR-40 total score significantly declined on POD1 and POD2 and returned to baseline levels on POD3 (p<0.001). H2O2 levels significantly decreased from T0 to T3 and then, increased at T4 (p=0,011). Changes of TBARS and H2O2 from T0 to T3 showed significant and negative correlation (r=−0.303, p=0.046). There was no significant correlation between QoR-40 total score and any parameter of oxidative stress response (p>0.05). Changes in TBARS levels from T0 to T3 were statistically significant between the study subgroups primarily due to increase of the concentrations in patients receiving paracetamol (p=0.031). Patients age, duration of surgery and cigarette smoking status showed significant influcences on and association with some oxidative stress response markers (TBARS, O2−, CAT) (p<0.05). Women who underwent hysterectomy had significant changes of H2O2 and TBARS activity however, those changes were not associated with changes of QoR-40 total scores during recovery.

Effects of Ischemic and Proton Pump Inhibitors Preconditioning on Oxidative Stress of Isolated Rat Heart

Abstract Aim of present study was to determine the participation of various biomarkers of oxidative damage: nitrite (NO2−), superoxide anion radicals (O2−), index of lipid peroxidation (TBARS) and hydrogen peroxide (H2O2) in coronary circulation after application of the different models of preconditioning such as ischemic and preconditioning with proton pump inhibitors. Examining a biochemical markers of oxidative damage we did not notice any increased production values of any parameter, according to that we can hypothesize that possible occurrence of reperfusion injury after ischemia and PPIs preconditioning is not mediated by this mechanism. Due to the very difficult and controversial application of ischemic preconditioning in clinical practice, the results of this study suggest that in the future proton pump inhibitors can contribute to the prevention of myocardial damage following ischemia

The Effects of Potassium Cyanide on the Functional Recovery of Isolated Rat Hearts after Ischemia and Reperfusion: The Role of Oxidative Stress

This investigation is aimed at examining the effects of pharmacological PostC with potassium cyanide (KCN) on functional recovery, gene expression, cytochrome c expression, and redox status of isolated rat hearts. Rats were divided into the control and KCN groups. The hearts of male Wistar albino rats were retrogradely perfused according to the Langendorff technique at a constant perfusion pressure of 70 cmH2O. After stabilisation, control hearts were subjected to global ischemia (5 minutes), followed by reperfusion (5 minutes), while experimental hearts underwent global ischemia (5 minutes) followed by 5 minutes of reperfusion with 10 μmol/L KCN. The following parameters of heart function were measured: maximum and minimum rates of pressure development, systolic and diastolic left ventricular pressure, heart rate, and coronary flow. Levels of superoxide anion radical, hydrogen peroxide, nitrites, and index of lipid peroxidation (measured as thiobarbituric acid-reactive substances) were measured in coronary venous effluent, and activity of catalase was determined in heart tissue. Expression of Bax, Bcl-2, SOD-1, SOD-2, and cytochrome c was studied as well. It was shown that expression of Bax, Bcl-2, and SOD-2 genes did not significantly differ between groups, while expression of SOD-1 gene and cytochrome c was lower in the KCN group. Our results demonstrated that KCN improved the recovery of myocardial contractility and systolic and diastolic function, enhanced catalase activity, and diminished generation of prooxidants. However, all possible mechanisms and potential adverse effects of KCN should be further examined in the future.