Effects of bisaramil on coronary-occlusion-reperfusion injury and free-radical-induced reactions

Antioxidant effect of garlic (Allium sativum) and black seeds (Nigella sativa) in healthy postmenopausal women

Objectives:

The objective of this study is to investigate the antioxidant effects of garlic extract and crude black seeds’ consumption on blood oxidant/antioxidant levels in healthy postmenopausal women.

Methods:

In total, 30 healthy postmenopausal women (mean age = 50.31 ± 4.23 years) participated. They ingested two garlic soft gels per day (each is equivalent to 1000 mg of fresh garlic bulb) and crude black seed grounded to powder in a dose of 3 g/day for 8 weeks. Oxidant (malondialdehyde) activity in plasma and antioxidants superoxide dismutase and glutathione peroxidase activities in erythrocytes were studied.

Results:

Significant low levels of plasma malondialdehyde with increased erythrocyte glutathione peroxidase and superoxide dismutase activities.

Discussion:

Menopause is associated with an increase in oxidative stress and a decrease in some antioxidant parameters. Consumption of garlic extracts and crude black seeds may have a beneficial effect on improved balance between blood oxidants and antioxidants in healthy postmenopausal women.

Natural antioxidant-isoliquiritigenin ameliorates contractile dysfunction of hypoxic cardiomyocytes via AMPK signaling pathway

Isoliquiritigenin (ISL), a simple chalcone-type flavonoid, is derived from licorice compounds and is mainly present in foods, beverages, and tobacco. Reactive oxygen species (ROS) is a critical factor involved in modulating cardiac stress response signaling during ischemia and reperfusion. We hypothesize that ISL as a natural antioxidant may protect heart against ischemic injury via modulating cellular redox status and regulating cardioprotective signaling pathways. The fluorescent probe H2DCFDA was used to measure the level of intracellular ROS. The glucose uptake was determined by 2-deoxy-D-glucose-(3)H accumulation. The IonOptix System measured the contractile function of isolated cardiomyocytes. The results demonstrated that ISL treatment markedly ameliorated cardiomyocytes contractile dysfunction caused by hypoxia. ISL significantly stimulated cardioprotective signaling, AMP-activated protein kinase (AMPK), and extracellular signal-regulated kinase (ERK) signaling pathways. The ROS fluorescent probe H2DCFDA determination indicated that ISL significantly reduced cardiac ROS level during hypoxia/reoxygenation. Moreover, ISL reduced the mitochondrial potential (Δψ) of isolated mouse cardiomyocytes. Taken together, ISL as a natural antioxidant demonstrated the cardioprotection against ischemic injury that may attribute to the activation of AMPK and ERK signaling pathways and balance of cellular redox status.

Protective effects of Ping-Lv-Mixture (PLM), a medicinal formula on arrhythmias induced by myocardial ischemia-reperfusion

Ping-Lv-Mixture (PLM) is a Chinese medicinal formula. The present study aimed to determine the effects of PLM on myocardial ischemia-reperfusion (MI/R) induced arrhythmias in rats. Arrhythmia model was established by occlusion of the left arterial descending coronary artery and thereafter reperfusion. A lead II electrocardiogram was monitored throughout the experiment. The results showed that pretreatment of PLM to MI/R rats significantly reduced the incidence and duration of ventricular tachycardia and ventricular fibrillation. On induction of MI/R, the activities of creatine kinase and lactate dehydrogenase were increased in vehicle group. PLM (0.04-1.00 g/kg) administration prevented the increase of these enzymes. Moreover, a significant increase of myocardium superoxide dismutase and decrease of malondialdehyde contents were observed in rats of PLM groups. On the other hand, the expressions of platelet activating factor (PAF) receptor mRNA was down-regulated in a dose-dependent manner in the PLM-treated groups by RT-PCR. Thus, it can be concluded that pretreatment with PLM inhibited lipid peroxidation in rats through suppressing the expression of PAF receptor, which may contribute to its preventive effect on myocardial ischemia-reperfusion induced arrhythmias.

Metallothionein mediates cardioprotection of isoliquiritigenin against ischemia-reperfusion through JAK2/STAT3 activation

AIM

To examine whether isoliquiritigenin (ISL) can attenuate myocardial ischemiareperfusion (MI/R) injury in rats by inducing metallothionein (MT) through activation of janus kinase 2 (JAK 2)/signal transducers and activators of transcription 3 (STAT 3) pathway.

METHODS

The experimental model of MI/R in rats was generated by 30 min of ischemia and reperfusion for 2 h. The mRNA expression of MT, COX-2, and iNOS were measured by RT-PCR. The protein expressions of MT, JAK/STAT, extracellular signal-regulated kinase (ERK), and Akt were determined by Western blotting in the absence or presence of a JAK kinase inhibitor, tyrphostin AG490 (1.0 mg/kg, iv, 1 h before ischemia).

RESULTS

Pretreatment with ISL markedly decreased the severity of reperfusion-induced arrhythmias and myocardial infarct size. In the ISL 20 mg/kg group, the activities of lactate dehydrogenase (LDH) and creatinine phosphokinase (CPK) were reduced by 38.4% and 51.3% when compared with the vehicle group. Increased JAK 2/STAT 3 phosphorylation was accompanied by increased synthesis of MT but not of COX-2 or iNOS in ISL-treated groups. AG490 can significantly weaken ISL-induced cardioprotection and prevent the increase of MT expression and JAK 2/STAT 3 phosphorylation.

CONCLUSION

ISL protected MI/R injury through activation of JAK 2/STAT 3 signal transduction pathway, which might be involved in mediating the upregulation of MT expression.

Retroinfusion of NFkappaB decoy oligonucleotide extends cardioprotection achieved by CD18 inhibition in a preclinical study of myocardial ischemia and retroinfusion in pigs

Myocardial reperfusion injury is partially mediated by postischemic inflammation. Beyond acute PMN recruitment, postischemic inflammation comprises subacute PMN adhesion, eg via NFkappaB activation. In a pig model of 60-min LAD occlusion by PTCA ballon inflation and 1 to 7 days of reperfusion, we investigated the impact of targeted NFkappaB decoy oligonucleotide (ODN) transfection in the area at risk (AAR) on infarct size and regional myocardial function. After 55 min of LAD occlusion, liposomes containing NFkappaB ODN were selectively retroinfused into the anterior interventricular vein for 5 min. Then, retroinfusion was stopped and reperfusion was initiated. Where indicated, CD18 antibody IB4 was infused systemically at 30 min of ischemia. Methylen blue and tetrazolium-red staining were used for quantification of the infarct size. Subendocardial segment shortening (SES) by sonomicrometric crystals in infarct area and AAR was assessed under pacing (expressed as % of control region). NFkappaB decoy ODN retroinfusion reduced infarct size (36 +/- 4% versus 49 +/- 5% in control hearts at day 7), whereas functional reserve of the AAR (SES 73 +/- 17% versus 46 +/- 18% at 180/min) tended to improve. Similar effects were observed after IB4 infusion (38 +/- 5% infarct size, 85 +/- 7% SES at 180/min). A combination of NFkappaB decoy ODN retroinfusion and IB4 infusion further decreased infarct size (26 +/- 2%) and improved functional reserve (SES 94 +/- 6% at 180/min). We conclude that NFkappaB decoy ODN transfection by retroinfusion is feasible in pig hearts and provides postischemic cardioprotection in addition to CD18 blockade.

Effects of acute exposure to the radiofrequency fields of cellular phones on plasma lipid peroxide and antioxidase activities in human erythrocytes

Radiofrequency fields of cellular phones may affect biological systems by increasing free radicals, which appear mainly to enhance lipid peroxidation, and by changing the antioxidase activities of human blood thus leading to oxidative stress. To test this, we have investigated the effect of acute exposure to radiofrequency fields of commercially available cellular phones on some parameters indicative of oxidative stress in 12 healthy adult male volunteers. Each volunteer put the phone in his pocket in standby position with the keypad facing the body. The parameters measured were lipid peroxide and the activities of superoxide dismutase (SOD), total glutathione peroxidase (GSH-Px) and catalase. The results obtained showed that the plasma level of lipid peroxide was significantly increased after 1, 2 and 4 h of exposure to radiofrequency fields of the cellular phone in standby position. Moreover, the activities of SOD and GSH-Px in human erythrocytes showed significant reduction while the activity of catalase in human erythrocytes did not decrease significantly. These results indicate that acute exposure to radiofrequency fields of commercially available cellular phones may modulate the oxidative stress of free radicals by enhancing lipid peroxidation and reducing the activation of SOD and GSH-Px, which are free radical scavengers. Therefore, these results support the interaction of radiofrequency fields of cellular phones with biological systems.

Effects of bisaramil, a novel class I antiarrhythmic agent, on heart, skeletal muscle and brain Na+ channels

The effects of bisaramil, a novel diazabicyclononane antiarrhythmic agent, were compared to those of lidocaine, a clinically used class Ib antiarrhythmic agent, on heart, skeletal muscle and brain Na+ channels expressed in Xenopus laevis oocytes using a two-electrode voltage clamp. Both bisaramil and lidocaine produced a concentration-dependent tonic block of Na+ current that was most effective on cardiac channels, but bisaramil was more potent than lidocaine. Both drugs produced a concentration-dependent shift in the voltage-dependence of inactivation and delayed recovery from inactivation. Bisaramil produced marked frequency-dependent block of heart channels and mild frequency-dependent block of skeletal muscle and brain channels, whereas lidocaine produced marked frequency-dependent block of all three channel types. Therefore, bisaramil shows tonic and frequency-dependent blockade that is most potent against the heart Na+ channel, which may account for its potent antiarrhythmic efficacy in vivo, and may result in reduced central nervous system toxicity compared to clinically used agents such as lidocaine.

Bisaramil and antiarrhythmics as inhibitors of free radical generation

The aim of this study was to investigate the effect of bisaramil--an antiarrhythmic drug under clinical trials-on free radical generation of isolated polymorph neutrophil granulocytes (PMN) and furthermore to compare its activity to that of well-known antiarrhythmics which have different modes of action. PMNs were isolated from healthy beagle dogs, and superoxide radical generation was induced by phorbol-myristate-acetate. Stimulated free radical generation capacity of PMNs and the time lag necessary for the initiation of free radical production were measured. All compounds were used at the concentrations of 10, 25, 50, 75, 100 micrograms ml-1. None of the antiarrhythmics stimulated by itself the free radical generation. Bisaramil exerted concentration dependent inhibitory effect on PMA-stimulated free radical generation and prolonged the time lag concentration dependently. At the investigated concentration range of antiarrhythmics only propafenon, mexiletine and diltiazem showed similar activity to bisaramil, but clear concentration dependency could not be seen in any of the cases. According to the results of this study inhibition of the stimulated free radical production of isolated PMNs cannot be closely connected merely to either membrane stabilizing or Ca-antagonistic activity of drugs. In vitro and earlier measured in vivo inhibitory action of bisaramil on free radical generation indicate a possible cardioprotective effect existing independently from its antiarrhythmic one. This observation may be important in outlining of the clinical indication field of bisaramil, and may be useful in the treatment of reperfusional damage.