Protective effects of clopidogrel on oxidant damage in a rat model of acute ischemia

Antioxidant Properties of Oral Antithrombotic Therapies in Atherosclerotic Disease and Atrial Fibrillation

The thrombosis-related diseases are one of the leading causes of illness and death in the general population, and despite significant improvements in long-term survival due to remarkable advances in pharmacologic therapy, they continue to pose a tremendous burden on healthcare systems. The oxidative stress plays a role of pivotal importance in thrombosis pathophysiology. The anticoagulant and antiplatelet drugs commonly used in the management of thrombosis-related diseases show several pleiotropic effects, beyond the antithrombotic effects. The present review aims to describe the current evidence about the antioxidant effects of the oral antithrombotic therapies in patients with atherosclerotic disease and atrial fibrillation.

Supplementation of Lipoic Acid, Zinc and Clopidogrel Reduces Mortality Rate and Incidence of Ventricular Arrhythmia in Experimental Myocardial Infarction

Despite the significant advances in management of coronary heart diseases, myocardial infarction (MI) is still associated with a high mortality rate. The present study was planned to investigate the possible protective effects of the anti-oxidants lipoic acid and zinc sulfate as well as the anti-platelet clopidogrel on cardiac dysfunction in experimental isoproterenol (ISO)-induced MI, aiming at achieving useful means for protection and therapy against MI. Wistar rats of both sexes were allocated into five groups: control, untreated MI and MI pre-treated with lipoic acid, zinc, or clopidogrel. All rats were subjected to ECG recording and measurement of plasma levels of troponin I, creatine kinase-MB (CK-MB) unit, triglycerides and total cholesterol. The hearts were isolated and studied on Langendorff preparation for assessment of intrinsic cardiac activities. The results revealed that the percent mortality was markedly reduced upon pre-treatment and the total arrhythmia was also decreased except for the zinc pre-treated rats. The ST-segment elevation was significantly reduced and the plasma levels of CK-MB were only decreased in lipoic acid and clopidogrel pre-treated rats with variable hypolipidemic effect. Hearts of clopidogrel pre-treated rats showed augmented inotropic activity both basal and in response to β-adrenergic stimulation. While zinc pre-treated hearts revealed improved rate of contraction and increased myocardial flow rate. Overall, these results indicate that lipoic acid, zinc and clopidogrel were variably effective in modifying the ISO-induced MI insults and offered partial protection against experimental myocardial damage.

An evaluation of rivaroxaban and clopidogrel in a rat lower extremity ischemia-reperfusion model: An experimental study

Background

This study aims to compare clopidogrel and rivaroxaban against ischemia-reperfusion injury after a long reperfusion time and to investigate its effects on various tissues.

Methods

A total of 40 Wistar rats were included in the study and were randomly divided into four groups (n=10 per group). Groups were defined as follows: control (Group 1), sham (Group 2), clopidogrel pre-treatment (Group 3), and rivaroxaban pre-treatment (Group 4). Ischemia (6 h) and reperfusion (8 h) were induced at the lower hind limb in Groups 2, 3, and 4. The ischemic muscle, heart, kidney, liver, and plasma tissues of the subjects were obtained to test for the oxidant (malondialdehyde) and antioxidants (glutathione, superoxide dismutase, and nitric oxide).

Results

Malondialdehyde levels were significantly higher in the sham group, compared to the controls in all tissues. Clopidogrel and rivaroxaban pre-treatment significantly decreased malondialdehyde levels, compared to the heart, ischemic muscle, liver, and blood tissues of the sham group. Kidney malondialdehyde levels were reduced only by rivaroxaban. Group 4 had significantly decreased malondialdehyde levels, compared to Group 3 in ischemic muscle (p<0.010). The glutathione reduction, compared to sham group, in the kidney was only significant for Group 4 (p<0.050). With clopidogrel and rivaroxaban pretreatment, nitric oxide levels significantly decreased only in the heart tissue, compared to sham group (p<0.001 and p<0.050, respectively).

Conclusion

The study results suggest that rivaroxaban and clopidogrel are effective in reducing ischemia-reperfusion injury in the heart, ischemic muscle, liver, and blood. Rivaroxaban also protects the kidneys and is superior to clopidogrel in ischemic muscle protection.

The Effect of Clopidogrel on the Response to Ischemia Reperfusion

Reperfusion in the setting of acute ischemia is essential in limiting tissue necrosis. However, reperfusion itself is associated with significant adverse effects. There is animal evidence that platelets play a role in the adverse effects of ischemia and reperfusion (IR) injury. We examined whether clopidogrel would have favorable effects on endothelial dysfunction induced by an episode of IR. Using a parallel design, we administered clopidogrel 600 mg or matching placebo to normal volunteers (n = 20) 24 hours before an episode of IR. Flow-mediated dilatation (FMD, radial artery) was assessed before and after 20 minutes of upper arm ischemia. Following IR, there was a highly significant decrease in FMD in the placebo group (7.6% ± 1.3% vs 3.4% ± 0.1%; P < .001). In the clopidogrel group, there was no change in FMD post-IR (8.3% ± 0.8% vs 7.1% ± 1.2%; P = not significant). Following IR, FMD in the placebo group was significantly smaller than that observed in the clopidogrel group ( P < .01). Ischemia and reperfusion caused no change in plasma levels of biomarkers of inflammation (intercellular adhesion molecule 1, chemokine ligand 5, and interleukin 6) in either group. Therefore, a single dose of clopidogrel given 24 hours prior to an episode of IR had protective effects, limiting the adverse effects of ischemia on endothelial function.

Protective effects of ginseng extracts and common anti-aggregant drugs on ischaemia-reperfusion injury

OBJECTIVE

Ginseng is a traditional herbal medicinal product widely used for various types of diseases because of its cellular protective effects. Possible protective effects of ginseng were investigated in blood, cardiac and renal tissue samples and compared with common anti-aggregant agents in an animal ischaemia-reperfusion (I/R) model.

METHODS

Twenty rats were equally divided into four different groups as follows: control group (I/R-induced group without drug use), group I (acetylsalicylic acid-administered group), group II (clopidogrel bisulfate-administered group), group III (ginsenoside Rb1-administered group). For the groups assigned to a medication, peripheral I/R was induced by clamping the femoral artery one week after initiation of the specified medication. After reperfusion was initiated, cardiac and renal tissues and blood samples were obtained from each rat with subsequent analysis of nitrogen oxide (NOx), malondialdehyde (MDA), paraoxonase 1 (PON1) and prolidase.

RESULTS

NOx levels were similar in each group. Significant decrements were observed in serum PON1 levels in each group when compared with the control (p < 0.05). Serum MDA levels were significantly lower in groups II and III (p < 0.05). Ameliorated renal prolidase levels were detected in study groups (p < 0.05) and recovered cardiac prolidase levels were obtained in groups II and III (p < 0.05).

CONCLUSION

These findings indicate that ginseng extracts may have a potential beneficial effect in I/R injury. However, more comprehensive studies are required to clarify the hypothetical cardiac, renal and systemic protective effects in reperfusion-induced oxidative damage.

Effect of N-acetylcysteine and allopurinol combination to protect spinal cord ischemia/reperfusion injury induced by aortic cross-clamping in rat model

Purpose

The aim of this experimental study was to determine whether combination of N-acetylcysteine and allopurinol can reduce the ischemia/reperfusion injury of spinal cord in a rat model.

Methods

Twenty-seven Spraque Dawley rats, all male, weighing between 220 to 370 (mean 325) gr were used in the study. 27 rats were divided into three groups: sham group, control group and experimental group. Abdominal aortic occlusion between the renal arteries and iliac bifurcations was carried out for 60 min with proximal and distal clip in control and experimental groups. Hindlimb motor functions were evaluated at 24, and 48 h using the Tarlov Scale. Besides, spinal cord samples were taken for determination of superoxide dismutase, and catalase activities as antioxidant enzymes, and malondialdehyde as an indicator of lipid peroxidation and xanthine oxidase levels as source hydroxyl radical for biochemical studies. Also, histopathological evaluation was made from cord tissue samples.

Results

The experimental group subjects had better neurological functions than control group subjects. In experimental group; superoxide dismutase and catalase levels increased, while malondialdehyde and xantine oxidase levels decreased as compared with control group. Histopathological examination showed that experimental group had less cell degeneration, hemorrhage, edema and inflammation loss than control group.

Conclusions

This study offers that combined use of N-acetylcysteine and allopurinol might help protect the spinal cord against ischemia/reperfusion injury.

Blood reflects tissue oxidative stress: a systematic review

We examined whether the levels of oxidative stress biomarkers measured in blood reflect the tissue redox status. Data from studies that measured redox biomarkers in blood, heart, liver, kidney and skeletal muscle were analyzed. In seven out of nine investigated redox biomarkers (malondialdehyde, reduced glutathione, superoxide dismutase, catalase, glutathione peroxidase, vitamin C and E) there was generally good qualitative and quantitative agreement between the blood and tissues. In contrast, oxidized glutathione and the reduced to oxidized glutathione ratio showed poor agreement between the blood and tissues. This study suggests that most redox biomarkers measured in blood adequately reflect tissue redox status.

Contribution of RhoA/Rho-kinase/MEK1/ERK1/2/iNOS pathway to ischemia/reperfusion-induced oxidative/nitrosative stress and inflammation leading to distant and target organ injury in rats

The small G protein RhoA and its downstream effector Rho-kinase play an important role in various physiopathological processes including ischemia/reperfusion (I/R) injury. Reactive oxygen and nitrogen species produced by iNOS and NADPH oxidase are important mediators of inflammation and organ injury following an initial localized I/R event. The aim of this study was to determine whether RhoA/Rho-kinase signaling pathway increases the expression and activity of MEK1, ERK1/2, iNOS, gp91(phox), and p47(phox), and peroxynitrite formation which result in oxidative/nitrosative stress and inflammation leading to hindlimb I/R-induced injury in kidney as a distant organ and gastrocnemius muscle as a target organ. I/R-induced distant and target organ injury was performed by using the rat hindlimb tourniquet model. I/R caused an increase in the expression and/or activity of RhoA, MEK1, ERK1/2, iNOS, gp91(phox), p47(phox), and 3-nitrotyrosine and nitrotyrosine levels in the tissues. Although Rho-kinase activity was increased by I/R in the kidney, its activity was decreased in the muscle. Serum and tissue MDA levels and MPO activity were increased following I/R. I/R also caused an increase in SOD and catalase activities associated with decreased GSH levels in the tissues. Y-27632, a selective Rho-kinase inhibitor, (100µg/kg, i.p.; 1h before reperfusion) prevented the I/R-induced changes except Rho-kinase activity in the muscle. These results suggest that activation of RhoA/Rho-kinase/MEK1/ERK1/2/iNOS pathway associated with oxidative/nitrosative stress and inflammation contributes to hindlimb I/R-induced distant organ injury in rats. It also seems that hindlimb I/R induces target organ injury via upregulation of RhoA/MEK1/ERK1/2/iNOS pathway associated with decreased Rho-kinase activity.

The CXCR1/2 ligand NAP-2 promotes directed intravascular leukocyte migration through platelet thrombi

Thrombosis promotes leukocyte infiltration into inflamed tissues, leading to organ injury in a broad range of diseases; however, the mechanisms by which thrombi guide leukocytes to sites of vascular injury remain ill-defined. Using mouse models of endothelial injury (traumatic or ischemia reperfusion), we demonstrate a distinct process of leukocyte recruitment, termed "directed intravascular migration," specifically mediated by platelet thrombi. Single adherent platelets and platelet aggregates stimulated leukocyte shape change at sites of endothelial injury; however, only thrombi were capable of inducing directed intravascular leukocyte migration. Leukocyte recruitment and migration induced by platelet thrombi occurred most prominently in veins but could also occur in arteries following ischemia-reperfusion injury. In vitro studies demonstrated a major role for platelet-derived NAP-2 (CXCL-7) and its CXCR1/2 receptor in regulating leukocyte polarization and motility. In vivo studies demonstrated the presence of an NAP-2 chemotactic gradient within the thrombus body. Pharmacologic blockade of CXCR1/2 as well as genetic deletion of NAP-2 markedly reduced leukocyte shape change and intrathrombus migration. These studies define a distinct process of leukocyte migration that is initiated by homotypic adhesive interactions between platelets, leading to the development of an NAP-2 chemotactic gradient within the thrombus body that guides leukocytes to sites of vascular injury.

The impact of commercially available purinergic ligands on purinergic signalling research

Due to the extremely wide-spread expression of purinergic receptors, purinergic signalling has been implicated in numerous physiological and pathophysiological areas. To better understand the involvement of purinergic receptors in such areas, the researcher's requirement for diverse and varied purinergic receptor ligands has greatly increased. This has generated increased commercial opportunities for life science suppliers, and ultimately, has led to a rapid expansion in the number of commercially available purinergic receptor ligands. The wide-spread availability of ligands to researchers has greatly benefited the scientific community, nurturing the rapid and continued expansion of the purinergic signalling field.

Beneficial effects of clopidogrel on glycemic indices and oxidative stress in patients with type 2 diabetes

Objective of present study is to evaluate the possible role of clopidogrel in improving glycemic indices and oxidative stress in patients with type 2 diabetes. This study was performed on 42 uncontrolled type 2 diabetic patients at the specialized center for Endocrinology and Diabetes, Al-Rasafa Directorate of Health, Baghdad. All of the patients were treated with (glibenclamide 5 mg at morning) and randomized into two groups: the first group includes 22 patients treated with clopidogrel tablets (75 mg/day) for 2 months; the second group includes 20 patients treated with a placebo formula (sodium bicarbonate 200 mg/day) for the same period. Treatment with clopidogrel produced significant improvement (P < 0.05) in fasting serum glucose (FSG), fasting serum insulin level, quantitative insulin sensitivity check index (QUICKI); and oxidative stress markers: serum malondialdehyde (MDA) and serum reduced glutathione (GSH) compared to their baseline levels. There was significant elevation (P < 0.05) in both FSG and fasting serum insulin and the MDA level with significant reduction (P < 0.05) in QUICKI of placebo group compared to their baseline levels. However, clopidogrel produced significant elevation (P < 0.05) in AST and ALT levels but placebo formula caused no significant alteration (P > 0.05) in the serum levels of these two enzymes. In conclusion the treatment with clopidogrel improved glycemic indices and reduced oxidative stress in patients with type 2 diabetes.

Metallothionein enhances angiogenesis and arteriogenesis by modulating smooth muscle cell and macrophage function

OBJECTIVE

In a previous study we identified metallothionein (MT) as a candidate gene potentially influencing collaterogenesis. In this investigation, we determined the effect of MT on collaterogenesis and examined the mechanisms contributing to the effects we found.

METHODS AND RESULTS

Collateral blood flow recovery was assessed using laser Doppler perfusion imaging, and angiogenesis was measured using a Matrigel plug assay. Smooth muscle cells were isolated from MT knockout (KO) mice for functional assays. Gene expression of matrix metalloproteinase-9, platelet-derived growth factor, vascular endothelial growth factor, and Fat cadherin in smooth muscle cells was measured by real-time polymerase chain reaction, and protein levels of vascular endothelial growth factor and matrix metalloproteinase-9 were determined using enzyme-linked immunosorbent assay and Western blot. CD11b(+) macrophages were tested for invasiveness using a real-time impedance assay. Both flow recovery and angiogenesis were impaired in MT KO mice. Proliferation, migration, and invasion were decreased in MT KO smooth muscle cells, and matrix metalloproteinase-9, platelet-derived growth factor, and vascular endothelial growth factor expression were also decreased, whereas FAT-1 cadherin expression was elevated. MT KO CD11b(+) cells were more invasive than wild-type cells.

CONCLUSIONS

MT plays an important role in collateral flow recovery and angiogenesis, an activity that appears to be mediated, in part, by the effects of MT on the functionality of 3 cell types essential for these processes: endothelial cells, smooth muscle cells, and macrophages.

The Effect of Aprotinin on Brain Ischemic-Reperfusion Injury After Hemorrhagic Shock in Rats: An Experimental Study

BACKGROUND

We aimed to demonstrate the positive effects of the serine protease inhibitor aprotinin on neural ischemia-reperfusion injury and apoptosis in a rat model.

METHODS

There were 18 rats divided into 3 groups: group A (sham, n = 6), group B (ischemia-reperfusion, n = 6), and group C (ischemia-reperfusion + aprotinin, n = 6). The systolic blood pressure of the group B and C rats was decreased to 40% to 50% of the normal level by taking blood from the femoral vein to develop hemorrhagic shock. The blood was retained and given to the remaining group B and C rats for reperfusion 20 minutes after the procedure. In group B, isotonic solution and, in group C, aprotinin was administered to the rats 5 minutes before reperfusion. After the rats were killed, the brain tissue samples were fixed for histopathologic examination. Brain tissue superoxide dismutase, malondialdehyde, and tissue myeloperoxidase level and apoptotic cell analyses were performed in all groups.

RESULTS

Superoxide dismutase level decreased from group A to group B and increased from group B to group C (p < 0.05). Malondialdehyde and myeloperoxidase levels and apoptotic cells increased from group A to group B and decreased from group B to group C (p < 0.05).

CONCLUSION

The results suggest that the systemic use of aprotinin in ischemic neural tissue prevents reperfusion injury and also protects the morphologic, functional, and biochemical integrity of the neural tissue.

The Evaluation of Protective Effects of FK-506 on Neural Ischemic-Reperfusion Injury: an Experimental Study

OBJECTIVE

In this study, we aimed to delineate the mode of neuroprotective action of FK-506, and demonstrated that FK-506 could decrease oxidative stress and apoptotic cell death in an in vivo rat model of neural ischemia-reperfusion after hemorrhagic shock.

METHODS

Thirty rats were used as experimental subjects and divided into five equal groups. Group A rats (sham group, n = 6) were anesthetized and craniotomies were performed for collecting brain tissue samples. In group B ischemia-reperfusion (I/R + 1 h, n = 6), group C (I/R + 24 h, n = 6), group D (I/ R + 1 h FK-506, n = 6) and group E (I/R + 24 h FK-506, n = 6), systolic blood pressure of the rats decreased to 40-50% of the normal level via bleeding from the femoral vein. Thus, a hemorrhagic shock and ischemic neural tissue model was formed. The bloodwas retained and given to the remaining animals in groups B, C,Dand E via femoral vein for reperfusion 20 min after the procedure. In group D and E, 1 mg/kg FK-506 in 0.5 ml isotonic solution was administered to the rats 5 min before reperfusion. Group B and D rats were sacrificed after 1 h and group Cand E rats were sacrificed 24 h after reperfusion; the rats were sacrificed via bleeding associated with intracardiac puncture. Craniotomy was also performed in groups B, C, D and E and brain tissue samples were fixed using neutral buffered 10% formaldehyde solution for immunohistopathological examination as in group A. Brain tissue superoxide dismutase (SOD) activities, malondialdehyde (MDA) levels, tissue myeloperoxydase (MPO) activities and apoptotic cell analyses with Apo 2.7 immunohistochemically were also performed in all groups.

RESULTS

The result of the study revealed that the SOD activities were lower for groups B (I/R + 1 h) and C (I/ R + 24 h) than for group A (sham group) (p < 0.05). In addition, SOD activities were higher in groups D (I/ R + 1 h FK-506) and E (I/R + 24 h FK-506) than in groups B (I/R + 1 h) and C (I/R + 24 h) (p < 0.05). MDA levels, MPO activities and the number of apoptotic cells were lower in group A (sham group) than in groups B (I/R + 1 h) and C (I/R + 24 h) (p < 0.05). In addition to these MDA levels, MPO activities and the number of apoptotic cells were higher in groups B (I/R + 1 h) and C (I/R + 24 h) as compared to groups D (I/R + 1 h FK-506) and E (I/R + 24 h FK-506) (p < 0.05).

CONCLUSION

The results suggest that the prophylactic use of FK-506 in an in situ ischemic neural tissue may prevent reperfusion injury.

Effect of Clopidogrel on Nitric Oxide Levels in an Ischemia Reperfusion Model

Ischemia and reperfusion injury is a pathologic process with serious consequences, arising due to interruption of arterial blood flow. Restored blood flow achieved after the ischemic period causes formation of oxygen radicals by activation of a variety of substances and systems. In this study, we investigated the effect of clopidogrel, an antithrombocyte agent, on tissue nitric oxide (NO) levels in an experimental ischemia reperfusion model. For this purpose, 6 hours of ischemia and 4 hours of subsequent reperfusion were applied to the right lower extremities of the subjects. Clopidogrel therapy was started in one of these groups 10 days before the process (study group). NO levels were measured in all groups in the muscle, lung, and liver tissues, and in plasma. Lung, plasma, and liver NO measurement values had statistically significant differences among the groups. There was no statistically significant difference in the measurements made on the muscle tissue. Clopidogrel, which has previously been reported to be suitable to be used as a preventive agent of ischemia reperfusion damage, has had a reducing effect on the NO levels in tissues in the ischemia reperfusion model created in our present study.

Suppression of angioplasty-related inflammation by pre-procedural treatment with trimetazidine

Percutaneous transluminal coronary angioplasty (PTCA) has been recognized as a reliable treatment procedure for acute reversible ischemia and reperfusion. Ischemic reperfusion cycle in PTCA leads to the systemic inflammation and extensive tissue injury by the production of reactive oxygen species including nitric oxide (NO) radicals. In patients with coronary artery disease, undergoing PTCA, the effects of trimetazidine (TMZ), a piperazine-derivative anti-anginal drug, were studied on several indirect markers of systemic inflammatory response: tumor necrosis factor-alpha (TNF-alpha), C-reactive protein (CRP) and NO products (nitrite and nitrate). Patients (n = 11 each group) were untreated or pre-treated with TMZ (20 mg per orally three times a day), begun three days prior to PTCA, and marker levels were measured before the start of TMZ therapy (baseline), just before PTCA (0 hr), and 4, 24, and 48 hrs after PTCA. The baseline levels of markers were not significantly different between the untreated and pre-treated patients. In contrast, all parameters were lower in the TMZ-treated group than those in the matched control group in the pre- and post-angioplasty periods. Interestingly, in the TMZ group, CRP and nitrite levels were significantly lower than in the control group at each time point of the pre- and post-angioplasty periods, but the TNF-alpha levels were significantly decreased only in the post-angioplasty period. Pre-procedural treatment with oral TMZ for three days significantly suppressed the elevation of inflammatory markers before and shortly after PTCA. We suggest the usefulness of TMZ in preventing inflammatory cardiovascular events after PTCA.