Polymerized placenta hemoglobin attenuates ischemia/reperfusion injury and restores the nitroso-redox balance in isolated rat heart

Protective effect and mechanism of low P50 haemoglobin oxygen carrier on isolated rat heart

The protection of the isolated heart is very important in heart transplantation surgery, meanwhile, the ischaemia/reperfusion (I/R) of the isolated heart is the main cause of its damage. A timely supply of oxygen can significantly improve the prevention of myocardial ischaemia, however, the cardioprotective solution does not have an oxygen supply function. Haemoglobin Based on Oxygen Carriers (HBOCs) is a kind of nano-oxygen drug, which can effectively and timely supply oxygen to hypoxic organs and tissues. However, the oxygen-carrying and releasing capacity (P50) is different with different HBOCs. The aim of our study was to investigate whether STS (a kind of cardioprotective solution, St Thomas Solution) +different P50 HBOCs provide superior myocardial protection and decrease myocardial injury compared to only STS in rats Langendorff isolated heart perfusion model. The results showed that STS + HBOCs can improve cardiac function at 37 °C for 35 min and 120 min, and reduce myocardial infarctions, pathological changes, and apoptosis of cardiomyocytes, and the STS + low P50 HBOCs is more effective than the other two higher P50 HBOCs. We further demonstrated the outstanding protective effect of STS + low P50 HBOCs on cardiac function, reducing myocardial infarctions and apoptosis of cardiomyocytes in rat Langendorff isolated heart perfusion model.

Hemoglobin-Based Oxygen Carriers: Potential Applications in Solid Organ Preservation

Ameliorating graft injury induced by ischemia and hypoxia, expanding the donor pool, and improving graft quality and recipient prognosis are still goals pursued by the transplant community. The preservation of organs during this process from donor to recipient is critical to the prognosis of both the graft and the recipient. At present, static cold storage, which is most widely used in clinical practice, not only reduces cell metabolism and oxygen demand through low temperature but also prevents cell edema and resists apoptosis through the application of traditional preservation solutions, but these do not improve hypoxia and increase oxygenation of the donor organ. In recent years, improving the ischemia and hypoxia of grafts during preservation and repairing the quality of marginal donor organs have been of great concern. Hemoglobin-based oxygen carriers (HBOCs) are “made of” natural hemoglobins that were originally developed as blood substitutes but have been extended to a variety of hypoxic clinical situations due to their ability to release oxygen. Compared with traditional preservation protocols, the addition of HBOCs to traditional preservation protocols provides more oxygen to organs to meet their energy metabolic needs, prolong preservation time, reduce ischemia–reperfusion injury to grafts, improve graft quality, and even increase the number of transplantable donors. The focus of the present study was to review the potential applications of HBOCs in solid organ preservation and provide new approaches to understanding the mechanism of the promising strategies for organ preservation.

Carbon Monoxide-Saturated Polymerized Placenta Hemoglobin Optimizes Mitochondrial Function and Protects Heart Against Ischemia-Reperfusion Injury

ABSTRACT

Ischemia-reperfusion (I-R) injury is detrimental to cardiovascular system. This study was designed to investigate whether carbon monoxide-saturated polymerized human placenta hemoglobin (CO-PolyPHb) attenuates cardiac I-R injury and to elucidate the underlying mechanism(s). Sixty male adult Sprague-Dawley rats were randomly divided into 6 groups: saline + sham group, PolyPHb + sham group, CO-PolyPHb + sham group, saline + I-R group, PolyPHb + I-R group, and CO-PolyPHb + I-R group. Rats were pretreated with injection of PolyPHb, CO-PolyPHb (0.5 g Hb/kg/d), or an equivalent volume of saline via caudal vein for 3 days. After pretreatment, hearts were isolated Langendorff perfused and subjected to 30-minute no-flow ischemia and 120-minute reperfusion. As compared with the saline + I-R group, pretreatment with CO-PolyPHb greatly improved the recovery of cardiac function, reduced infarct size, and suppressed the release of cardiac enzyme. Importantly, CO-PolyPHb showed more prominent cardioprotective effect than PolyPHb, exhibiting a promising therapeutic potential in cardiac I-R injury. Further study demonstrated that CO-PolyPHb activated molecular signaling toward mitophagy and significantly elevated the mitochondrial respiratory function in the heart. In addition, CO-PolyPHb upregulated the phosphorylation of the proteins in insulin signaling pathway and increased the glucose uptake rate in cardiomyocytes. Pharmacological inhibition of this pathway by wortmannin abrogated the anti-I-R effect of CO-PolyPHb. In conclusion, using an isolated rat heart model, we have demonstrated that pretreatment with CO-PolyPHb provided protective effect against cardiac I-R injury, and this protection was mediated by the improvement of mitochondrial function and activation of insulin signaling pathway in the heart.

Use of Hemoglobin for Delivering Exogenous Carbon Monoxide in Medicinal Applications

Carbon Monoxide (CO), at low concentrations, can have a variety of positive effects on the body including anti-apoptosis, anti-inflammatory, anti-oxidative and anti-proliferative effects. Although CO has great potential for use as a potent medical bioactive gas, for it to exist in the body in stable form, it must be associated with a carrier. Hemoglobin (Hb) represents a promising material for use as a CO carrier because most of the total CO in the body is stored associated with Hb in red blood cells (RBC). Attempts have been made to develop an Hb-based CO carrying system using RBC and Hb-based artificial oxygen carriers. Some of these have been reported to be safe and to have therapeutic value as a CO donor in preclinical and clinical studies. In the present review, we overview the potential of RBC and Hb-based artificial oxygen carriers as CO carriers based on the currently available literature evidence for their use in pharmaceutical therapy against intractable disorders.

Redox states of hemoglobin determine left ventricle pressure recovery and activity of mitochondrial complex IV in hypoxic rat hearts

Cardiovascular effects were reported to occur in humans and in animal models during transfusion with hemoglobin (Hb)-based oxygen therapeutics. The effects of Hb's iron redox states on cardiac parameters during hypoxia/reoxygenation are however poorly defined. We hypothesize that acute exposures to ferric Hb during hypoxia leads to cardiomyocyte injury and an impaired left ventricular response accompanied by cardiac mitochondrial bioenergetic dysfunction. Recovery of left ventricular functions in an isolated rat heart Langendorff perfusion system was observed following perfusion with ferrous but not with ferric Hb. Ferric Hb induced the development of heart lesions, and impairment of the respiratory chain complex activity. Under normoxia, a sharp decline in cardiac parameters was observed following co-perfusion of low (20 μM) and high (100 μM) ascorbic acid (Asc) with ferrous Hb. This trend continued with ferric Hb co-perfusion, but only at the higher concentration of Asc. These observations suggest that perfusion of the hypoxic heart with ferric Hb increases oxidative stress thereby resulting in cardiac dysfunction. Intervention with Asc to reduce ferric Hb may offer a strategy to control Hb toxicity; however, timing of administration, and dosage of Asc may require individual optimization to target specific redox forms of Hb.

Polydatin Protects Diabetic Heart against Ischemia-Reperfusion Injury via Notch1/Hes1-Mediated Activation of Pten/Akt Signaling

Diabetes exacerbates oxidative/nitrative stress during myocardial ischemia-reperfusion (MI/R) injury. Recent studies highlighted the cardioprotective actions of polydatin. However, its effect on diabetic MI/R injury and the underlying mechanisms remain unknown. This work was undertaken to evaluate the effect of polydatin on diabetic MI/R injury with a focus on Notch1/Hes1 signaling and myocardial oxidative/nitrative stress. Streptozotocin- (STZ-) induced diabetic rats were administered with polydatin (20 mg/kg/d) in the absence or presence of DAPT (a γ-secretase inhibitor) or LY294002 (a PI3K/Akt inhibitor) and then subjected to MI/R injury. Polydatin administration preserved cardiac function and reduced myocardial infarct size. Moreover, polydatin ameliorated myocardial oxidative/nitrative stress damage as evidenced by decreased myocardial superoxide generation, malondialdehyde, gp91^phox expression, iNOS expression, NO metabolite level, and nitrotyrosine content and increased eNOS phosphorylation. However, these effects were blocked by DAPT administration. DAPT also inhibited the stimulatory effect of polydatin on the Notch1/Hes1-Pten/Akt signaling pathway in a diabetic myocardium. Additionally, LY294002 not only abolished polydatin's antiapoptotic effect but also reversed its inhibitory effect on myocardial oxidative/nitrative stress. Polydatin effectively reduced MI/R injury and improved left ventricular functional recovery under diabetic condition by ameliorating oxidative/nitrative stress damage. Importantly, Notch1/Hes1-mediated activation of Pten/Akt signaling played a crucial role in this process.

Polymerized human placenta haemoglobin attenuates myocardial injury and aortic endothelial dysfunction in a rat model of severe burns

This study was designed to investigate the effect of polymerized human placenta haemoglobin (PolyPHb) on cardiac dysfunction after severe burns. A total of 60 male Sprague-Dawley rats were randomly divided into 3 groups: Sham, Burn and Burn + PolyPHb groups. Rats were subjected to third-degree burns to 30% of total body surface area and the haemodynamics, cardiac enzyme release and aortic endothelium ultrastructure/function were measured. PolyPHb (0.5 gHb/kg) greatly improved mean arterial pressure, left ventricular developed pressure (LVDP), maximum LVDP increase and decrease rate and reduced left ventricular end-diastolic pressure as compared to the Burn group. The plasma levels of cardiac enzyme including CK-MB and troponin I were also significantly down-regulated in the Burn + PolyPHb group. In addition, PolyPHb treatment markedly restored the endothelium-dependent relaxation impaired by severe burns and pathological changes of endothelium in aorta. Therefore, our data suggest that PolyPHb can limit severe burn-induced myocardial injury, which is associated with protection of aortic endothelium.

Carbon Monoxide-Saturated Hemoglobin-Based Oxygen Carriers Attenuate High-Altitude-Induced Cardiac Injury by Amelioration of the Inflammation Response and Mitochondrial Oxidative Damage

Objective: To investigate the therapeutic effect of carbon monoxide (CO) on high-altitude hypoxia-induced cardiac damage. Methods: Forty male C57BL/6 mice were randomly divided into 4 groups. The mice were exposed to normoxia or simulated 5,500-meter high-altitude hypoxia in a hypobaric chamber for 7 days. During the first 3 days, the mice were pretreated with CO-saturated hemoglobin (Hb)-based oxygen carrier (CO-HBOC), oxygen-saturated hemoglobin-based oxygen carrier (O2-HBOC) at a dose of 0.3 g Hb/kg/day or an equivalent volume of saline. The in vivo left ventricle function, cardiac enzyme release, histopathological changes, apoptosis and inflammation were also measured. Results: High-altitude hypoxia induced significant cardiac damage, as demonstrated by impaired cardiac function and increased proapoptotic, proinflammatory and pro-oxidant markers. Pretreatment with CO-HBOC significantly improved cardiac performance, reduced cardiac enzyme release and limited myocardial apoptosis. The increased inflammatory response was also suppressed. In addition to the preserved mitochondrial structure, hypobaric hypoxia-induced mitochondrial oxidative damage was remarkably attenuated. Moreover, these antiapoptotic and antioxidative effects were accompanied by an upregulated phosphorylation of Akt, ERK and STAT3. Conclusion: This study demonstrated that CO-HBOC provides a promising protective effect on high-altitude hypoxia-induced myocardial injury, which is mediated by the inhibition of inflammation and mitochondrial oxidative damage.

Antioxidant enzymes as redox-based biomarkers: a brief review

The field of redox proteomics focuses to a large extent on analyzing cysteine oxidation in proteins under different experimental conditions and states of diseases. The identification and localization of oxidized cysteines within the cellular milieu is critical for understanding the redox regulation of proteins under physiological and pathophysiological conditions, and it will in turn provide important information that are potentially useful for the development of novel strategies in the treatment and prevention of diseases associated with oxidative stress. Antioxidant enzymes that catalyze oxidation/reduction processes are able to serve as redox biomarkers in various human diseases, and they are key regulators controlling the redox state of functional proteins. Redox regulators with antioxidant properties related to active mediators, cellular organelles, and the surrounding environments are all connected within a network and are involved in diseases related to redox imbalance including cancer, ischemia/reperfusion injury, neurodegenerative diseases, as well as normal aging. In this review, we will briefly look at the selected aspects of oxidative thiol modification in antioxidant enzymes and thiol oxidation in proteins affected by redox control of antioxidant enzymes and their relation to disease. [BMB Reports 2015; 48(4): 200-208]

High-Dose Polymerized Hemoglobin Fails to Alleviate Cardiac Ischemia/Reperfusion Injury due to Induction of Oxidative Damage in Coronary Artery

Objective. Ischemia/reperfusion (I/R) injury is an unavoidable event for patients in cardiac surgery under cardiopulmonary bypass (CPB). This study was designed to investigate whether glutaraldehyde-polymerized human placenta hemoglobin (PolyPHb), a hemoglobin-based oxygen carrier (HBOC), can protect heart against CPB-induced I/R injury or not and to elucidate the underlying mechanism. Methods and Results. A standard dog CPB model with 2-hour cardiac arrest and 2-hour reperfusion was established. The results demonstrated that a low-dose PolyPHb (0.1%, w/v) provided a significant protection on the I/R heart, whereas the high-dose PolyPHb (3%, w/v) did not exhibit cardioprotective effect, as evidenced by the impaired cardiac function, decreased myocardial oxygen utilization, and elevated enzymes release and pathological changes. Further study indicated that exposure of isolated coronary arteries or human umbilical vein endothelial cells (HUVECs) to a high-dose PolyPHb caused impaired endothelium-dependent relaxation, which was companied with increased reactive oxygen species (ROS) production, reduced superoxide dismutase (SOD) activity, and elevated malonaldehyde (MDA) formation. Consistent with the increased oxidative stress, the NAD(P)H oxidase activity and subunits expression, including gp91^phox, p47^phox, p67^phox, and Nox1, were greatly upregulated. Conclusion. The high-dose PolyPHb fails to protect heart from CPB-induced I/R injury, which was due to overproduction of NAD(P)H oxidase-induced ROS and resultant endothelial dysfunction.

Angiotensin-converting enzyme inhibitor captopril reverses the adverse cardiovascular effects of polymerized hemoglobin

AIM

Cell-free hemoglobin-based oxygen carriers (HBOCs) may increase the risk of myocardial infarction and death. We studied the effect of an angiotensin-converting enzyme (ACE) inhibitor on HBOC-induced adverse cardiovascular outcomes and elucidated the underlying mechanisms.

RESULTS

With a dog cardiopulmonary bypass model, we demonstrated that a high-dose HBOC (3%, w/v) did not reduce-but aggravated-cardiac ischemia/reperfusion injury. Animals administered a high-dose HBOC experienced coronary artery constriction and depression of cardiac function. Exposure of isolated coronary arteries or human umbilical vein endothelial cells to high-dose HBOC caused impaired endothelium-dependent relaxation, increased endothelial cell necrosis/apoptosis, and elevated NAD(P)H oxidase expression (gp91(phox), p47(phox), p67(phox), and Nox1) and reactive oxygen species (ROS) production. All observed adverse outcomes could be suppressed by the ACE inhibitor captopril (100 μM). Co-incubation with free radical scavenger tempol or NAD(P)H oxidase inhibitor apocynin had no effect on captopril action, suggesting that the positive effects of captopril are ROS- and NAD(P)H oxidase dependent. ACE inhibition by captopril also contributed to these effects. In addition, bioavailable nitrite oxide (NO) reduced by high-dose HBOC was preserved by captopril. Furthermore, HBOC, at concentrations greater than 0.5%, inhibited large conductance Ca(2+)-activated K(+) channel currents in vascular smooth muscle cells in a dose-dependent manner, although captopril failed to improve current activity, providing additional evidence that captopril's effects are mediated by the endothelium, but not by the smooth muscle.

INNOVATION AND CONCLUSION

Captopril alleviates high-dose HBOC-induced endothelial dysfunction and myocardial toxicity, which is mediated by synergistic depression of NAD(P)H oxidase subunit overproduction and increases in vascular NO bioavailability.

Isovolemic hemodilution with glutaraldehyde-polymerized human placenta hemoglobin (PolyPHb) attenuated rat liver ischemia/reperfusion injury

This study was to investigate whether glutaraldehyde-polymerized human placenta hemoglobin (PolyPHb) could attenuate ischemia/reperfusion (I/R)-induced liver injury. Isovolemic hemodilution of SD rats was performed by exchanging 15% total blood volume with PolyPHb. I/R was induced by left liver lobes pedicle cross-clamping for 60 min and reperfusion for 2 h. Blood pressure moderately elevated after PolyPHb infusion and returned to basal level within 10 min. The hepatic histopathological damage and the activities of liver injury markers were reduced by PolyPHb. The TUNEL staining and caspase assay indicated hepatic apoptosis was also inhibited. Therefore, our findings suggest PolyPHb can reduce liver I/R injury.

Gastric antisecretory and antiulcer activity of bovine hemoglobin

AIM: To investigate gastric antisecretory and gastroprotective activity of bovine hemoglobin (B-Hb) in rats.

METHODS: Adult Albino-Wistar rats were divided into groups of 6 animals each. B-Hb in doses of 100, 300 and 900 mg/kg body weight was tested for gastric acid secretion and antiulcer activity. Gastric secretions were measured 6 h after pylorus ligation in rats pretreated with B-Hb. The acidity was measured by titrating gastric contents against 0.01 mol/L NaOH to pH 7. Indomethacin ulcers were produced by oral administration of 30 mg/kg bw in the rats pretreated with B-Hb one hour before indomethacin. Six hours after indomethacin stomach removed and ulcer index was recorded. Ethanol ulcer were produced by 1 mL of ethanol in the rats pretreated with B-Hb 30 min before the ethanol. One hour after ethanol stomach were cut open to score ulcers. Histological examination and analysis of gastric wall mucus, non-protein sulfhydryl groups (NP-SH), and myeloperoxidase (MPO) were carried in gastric tissue following ethanol administration.

RESULTS: In control rats pylorus ligation for 6 h resulted in the accumulation of 8.1 ± 0.61 mL of gastric secretion. The treatment of the rats with 100, 300 and 900 mg/kg of B-Hb produced a significant decrease in the volume of gastric secretion 5.6 ± 0.63, 5.5 ± 0.75 and 4.7 ± 0.58 mL respectively as compared to the control group [analysis of variance (ANOVA) F = 4.77, P < 0.05]. The lesion area in the control group was found to be 22.4 ± 3.2 mm² six hours after the administration of indomethacin. Treatment of rats with B-Hb at doses of 100 mg/kg (24.3 ± 3.29 mm²), 300 mg/kg (16.2 ± 1.45 mm²) and 900 mg/kg (12.6 ± 1.85 mm²) produced a dose dependent decreased the lesion scores (ANOVA F = 4.50, P < 0.05). The ulcer index following one hour after 1 mL ethanol was 7.1 ± 0.31. Pretreatment of rats with B-Hb at the doses of 100 mg/kg (2.5 ± 0.42), 300 mg/kg (2.1 ± 0.4) and 900 mg/kg (0.7 ± 0.21) significantly inhibited the formation of gastric lesions (ANOVA F = 63.26, P < 0.0001). Histological examination of gastric mucosa following ethanol showed significant lesions in the form of gastric pits with detachment of the surface epithelium; vacuolation of epithelial cells and elongation of microvessels. The changes were dose-dependently attenuated by B-Hb. The treatment of rats with ethanol significantly decreased the Alcian blue binding capacity of gastric wall mucus (480 ± 25.6 μg Alcian blue/g of tissue) as compared to control rats (667 ± 25.8 μg). Pretreatment of rats with B-Hb at the doses of 100 mg/kg (516 ± 31.6 μg/g), 300 mg/kg (558 ± 28.8 μg/g) and 900 mg/kg (654 ± 33.8 μg/g) significantly attenuated ethanol induced depletion of gastric wall mucus (ANOVA F = 8.05, P < 0.005). A significant and dose dependent increase of gastric mucosal NP-SH (ANOVA F = 19.62, P < 0.001) and decrease in MPO activity (ANOVA F = 3.1, P < 0.05) was observed in B-Hb treated rats.

CONCLUSION: B-Hb possesses significant gastric antisecretory and gastroprotective activity against experimentally induced gastric lesion. The gastroprotective effects of B-Hb are accompanied by inhibition of neutrophils activity, reduction of oxidative stress and maintenance of mucosal integrity.

Pretreatment with xenon protected immature rabbit heart from ischaemia/reperfusion injury by opening of the mitoKATP channel

BACKGROUND

The noble gas anaesthetic, xenon has previously been shown to protect the adult myocardium from ischaemia/reperfusion (I/R) injury, however its effect on immature myocardium is unclear. The aim of this study was to investigate the effect of xenon on the isolated immature heart.

METHODS

Isolated, immature (2-3weeks old) New Zealand rabbit hearts were perfused with Krebs-Henseleit buffer via Langendorff-mode. After 20min of baseline equilibration, hearts were pretreated with 75% xenon, 75% xenon+100μM diazoxide, or 75% xenon+100μM 5-hydroxydecanoate, and then subjected to 1h of global ischaemia and 3h of reperfusion.

RESULTS

Pretreatment with 75% xenon significantly improved cardiac function (P<0.01 vs. the I/R group, respectively), limited myocardial infarct size (20.83±2.16%, P<0.01 vs. 35.82±2.14% of the I/R group), reduced cardiac enzyme release (CK-MB, 1.00±0.19IU/L, P<0.01 vs. 0.44±0.14IU/L of the I/R group; LDH, 6.15±1.06IU/L P<0.01 vs. 3.49±0.37IU/L of the I/R group) and decreased apoptosis (6.17±0.56%, P<0.01 vs. 11.31±0.93% of the I/R group). In addition, the mitochondrial structure changes caused by I/R injury were largely prevented by 75% xenon pretreatment (1.37±0.16, P<0.01 vs. 2.32±0.13 of the I/R group). The mitochondrial adenosine triphosphate-sensitive potassium (mitoKATP) channel opener diazoxide did not influence the effect of xenon, but the specific mitoKATP channel blocker 5-hydroxydecanoate completely abolished this effect.

CONCLUSIONS

Our study demonstrated that pretreatment with 75% xenon protected immature heart from I/R injury, and this protection was probably mediated by preservation of myocardial mitochondria and opening of mitoKATP channel.

The effect of polymerized placenta hemoglobin on renal ischemia/reperfusion injury

The goal of this study was to investigate whether hemoglobin-based oxygen carrier (HBOC) attenuated ischemia/reperfusion (I/R)-induced kidney injury. Male SD rats were randomly divided into a sham group, I/R group, and HBOC group (injection of 0.1 gHb/kg PolyPHb). The ischemia was induced by bilateral renal pedicle cross-clamping for 45min. Then the clamp was released to allow 24h reperfusion. Without increasing blood pressure, PolyPHb reduced the blood urea nitrogen and creatinine in plasma and attenuated the tumor necrosis factor-α and interleukin-8 in kidney tissue. Therefore, our findings suggest that PolyPHb could reduce kidney injury after I/R injury, and this effect was probably associated with the depressed inflammatory response.

Resuscitation with polymerized human placenta hemoglobin attenuated hemorrhagic shock-induced lung injury

This study was designed to investigate whether polymerized human placenta hemoglobin (PolyPHb) attenuated hemorrhagic shock-induced lung injury. A mean arterial pressure (MAP) of 30mmHg was maintained for 60 min. Then, all the rats were randomly resuscitated with hetastarch, whole blood, or PolyPHb. The result indicated that PolyPHb greatly improved the MAP and pulmonary function, and significantly reduced the release of inflammatory cytokines, histopathological changes, and pulmonary edema. Therefore, our findings suggest that PolyPHb could reduce pulmonary injury after hemorrhagic shock, and this effect was probably associated with the depressed inflammatory response.

Polymerized human placenta hemoglobin given before ischemia protects rat heart from ischemia reperfusion injury

This study was to investigate whether polymerized human placenta hemoglobin (PolyPHb) given before ischemia protects in vivo rat heart function against ischemia/reperfusion (I/R) injury. Forty-five male Sprague-Dawley rats were randomly divided (n = 15 per group) into a sham group, control group (pretreatment with Lactated Ringer's solution), or PolyPHb group (pretreatment with 0.1 gHb/kg PolyPHb). Rat hearts were subjected to 30-min ischemia by occlusion of left anterior descending, followed by 2-hr reperfusion. As compared to the control group, PolyPHb preserved cardiac function and reduced cardiac troponin-I release and histopathological changes. Therefore, PolyPHb pretreatment provided a profound cardioprotective effect on the in vivo rat heart.

Alternative use of isoflurane and propofol confers superior cardioprotection than using one of them alone in a dog model of cardiopulmonary bypass

Our previous clinical study reported that isoflurane preconditioning and high-dose propofol posttreatment attenuated myocardial ischemia/reperfusion injury of patients in surgery with cardiopulmonary bypass (CPB). This study was designed to confirm this cardiac protection by use of a dog CPB model and to elucidate the related mechanism. Adult mongrel male dogs undergoing standard CPB were assigned into 4 groups: Sham group, Propofol group, Isoflurane (Iso) group and isoflurane in combination of propofol (pre-Iso+P) group. After induction, anesthesia was maintained with propofol (Propofol group), isoflurane (Iso group) or isoflurane preconditioning in combination with propofol posttreatment (pre-Iso+P group). After 2 h cardiac arrest and CPB, aortic cross-clamping was released to allow 2 h reperfusion. The results demonstrated that joint use of isoflurane and propofol facilitated cardiac functional recovery, improved myocardial oxygen utilization and decreased cardiac enzyme release. Also, the oxidative damage caused by ischemia/reperfusion injury was remarkably attenuated. Linear regression analysis showed that cardiac function performance and oxidative stress status were inversely correlated, indicating the improved cardiac function was in closed association with the attenuation of oxidative stress. In addition, the cardiac oxygen consumption (VO(2)) was found to be significantly associated with the above cardiac function and oxidative stress parameters, suggesting VO(2) was predictive for the levels of cardiac damage and oxidative stress. Therefore, we conclude that alternative use of isoflurane and propofol confers superior cardioprotection against postischemic myocardial injury and dysfunction, and this protection was probably mediated by attenuation of cardiac oxidative damage.

Cardioprotective effect of a hemoglobin-based oxygen carrier on cold ischemia/reperfusion injury

OBJECTIVES

The etiology of myocardial ischemia/reperfusion (I/R) injury is multifactorial, but activation of the innate immune system and the resulting inflammatory response are important components of I/R injury. The aim of this study was to investigate the protective effect of a hemoglobin-based oxygen carrier (HBOC) on cold I/R heart and to explore the underlying mechanisms.

METHODS

Isolated Sprague-Dawley rat hearts were perfused in the Langendorff mode. After 30 min of basal perfusion, rat hearts were arrested with histidine-tryptophan-ketoglutarate solution (HTKs) with or without an HBOC and hypothermically stored (4°C) for 9 or 14 h, followed by 2 h of reperfusion.

RESULTS

Compared with HTKs alone, the HBOC in HTKs greatly improved heart contraction and decreased infarct size, necrosis and apoptosis, which was related to the reduced expression of Toll-like receptor 2 (TLR 2), TLR 4, TNF-α, IL-1β and nuclear factor-κB (NF-κB) activation.

CONCLUSIONS

Our results demonstrated that the HBOC protected isolated rat heart from cold I/R injury and this protection was associated with attenuation of the expression of the TLR 2 and TLR 4/NF-κB signaling pathway, which may down-regulate the inflammatory response.

A novel hemoglobin-based oxygen carrier, polymerized porcine hemoglobin, inhibits H₂O₂-induced cytotoxicity of endothelial cells

Hemoglobin-based oxygen carriers (HBOCs), with their capacity for delivering oxygen, could potentially function as red blood cell substitutes or primary resuscitation solutions. However, there has been some concern regarding redox-related safety issues of HBOCs. The present study describes a novel function of polymerized porcine hemoglobin (pPolyHb) in protecting a human umbilical vein endothelial cell line from H₂O₂-induced cytotoxicity. Through the examination of H₂O₂ consumption and ferrylhemoglobin formation, we found that pPolyHb exhibits antioxidant activity, suggesting that pPolyHb may protect cells from free radical-induced cell damage. Additionally, we investigated the effect of pPolyHb on H₂O₂-induced cell cytotoxicity, and found that pPolyHb significantly inhibits H₂O₂-mediated endothelial cell damage as well as apoptosis. Thus, pPolyHb may be developed as a new HBOC in the future.

Polymerised placenta haemoglobin attenuates cold ischaemia/reperfusion injury in isolated rat heart

Ischaemia/reperfusion (I/R) injury is harmful to the cardiovascular system and is responsible for the inflammatory response, which, in turn, aggravates cardiac dysfunction. This study was designed to investigate the protective effect and potential mechanism of a haemoglobin-based oxygen carrier on cold I/R-injured hearts. Isolated Sprague-Dawley rat hearts were perfused in Langendorff mode. After a 30-min basal perfusion, rat hearts were arrested and hypothermically stored at 4°C for 12h followed by a 2-h reperfusion. Compared with histidine-tryptophan-ketoglutarate solution (HTKs), polymerised placenta haemoglobin (PolyPHb) in HTKs greatly improved heart contraction and decreased infarction size, necrosis, and apoptosis, which was related to reduced expression of TLR2, TLR4, TNF-α, and IL-1β, and NF-κB activation. Our results demonstrate the cardioprotective effect of PolyPHb on cold I/R-injured hearts and revealed that this protection was mediated in large part by attenuation of TLR2 and -4/NF-κB signalling pathway and could possibly down-regulate the inflammatory response.

Hemoglobin vesicle improves recovery of cardiac function after ischemia-reperfusion by attenuating oxidative stress in isolated rat hearts

Hemoglobin vesicle (HbV) could be a useful blood substitute in emergency medicine. The aim of this study was to clarify the effects of HbV on cardiac function after ischemia-reperfusion (I/R) ex vivo. Isolated rat hearts were perfused according to the Langendorff method. An ischemia-reperfusion group (n = 6) was subjected to 25 minutes of global ischemia and 30 minutes of reperfusion. HbV (hemoglobin, 0.33 g/dL) was perfused before ischemia-reperfusion for 10 minutes (HbV group, n = 6). Hemodynamics were monitored, and tissue glutathione contents were measured. The redox state of reactive thiols in cardiac tissues was assessed by the biotinylated iodoacetamide labeling method. Left ventricular developed pressure was significantly recovered in the HbV group after 30 minutes of reperfusion (56.3 ± 2.8 mm Hg vs. ischemia-reperfusion group 27.0 ± 8.0 mm Hg, P < 0.05). Hemodynamic changes induced by HbV were similar to those observed when N-nitro-L-arginine methyl ester was perfused for 10 minutes before ischemia-reperfusion (L-NAME group). The oxidized glutathione contents of cardiac tissues significantly decreased, and biotinylated iodoacetamide labeling of thiols was maintained in both the HbV and the L-NAME groups. HbV improved the recovery of cardiac function after ischemia-reperfusion in isolated rat hearts. This mechanism is dependent on functional protection against thiol oxidation.

Emergent role of gasotransmitters in ischemia-reperfusion injury

Nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) are lipid-soluble, endogenously produced gaseous messenger molecules collectively known as gasotransmitters. Over the last several decades, gasotransmitters have emerged as potent cytoprotective mediators in various models of tissue and cellular injury. Specifically, when used at physiological levels, the exogenous and endogenous manipulation of these three gases has been shown to modulate ischemia/reperfusion injury by inducing a number of cytoprotective mechanisms including: induction of vasodilatation, inhibition of apoptosis, modulation of mitochondrial respiration, induction of antioxidants, and inhibition of inflammation. However, while the actions are similar, there are some differences in the mechanisms by which these gasotransmitters induce these effects and the regulatory actions of the enzyme systems can vary depending upon the gas being investigated. Furthermore, there does appear to be some crosstalk between the gases, which can provide synergistic effects and additional regulatory effects. This review article will discuss several models and mechanisms of gas-mediated cytoprotection, as well as provide a brief discussion on the complex interactions between the gasotransmitter systems.

Pretreatment with hemoglobin-based oxygen carriers protect isolated rat heart from myocardial infarction

This study was designed to investigate whether polymerized human placenta hemoglobin (PolyPHb) pretreatment provided protection to the heart after ischemia/reperfusion (I/R) injury. After 10-min basal perfusion, isolated Sprague-Dawley rat hearts were pretreated with 0.1 gHb/dL PolyPHb and subjected to I/R injury. PolyPHb pretreatment greatly reduced the decreases in left ventricular developed pressure (LVDP), maximum LVDP increase and decrease rate (+/-dp/dt), and the increase in left ventricular end-diastolic pressure (LVEDP) as compared to the control group. Moreover, the myocardial infarction and troponin-I release were significantly reduced in the pre-HBOCs group. Therefore, PolyPHb pretreatment was protective to the isolated I/R heart.

Pretreatment before ischemia induction with polymerized human placenta hemoglobin (PolyPHb) attenuates ischemia/reperfusion injury-induced myocardial apoptosis

This study was designed to investigate the influence of polymerized human placenta hemoglobin (PolyPHb) pretreatment on ischemia/reperfusion (I/R) injury-induced myocardial apoptosis. Isolated Sprague-Dawley rat hearts were perfused by Langendorff model. After basal perfusion, hearts were arrested by St.Thomas' solution (STS) with (Pre-HBOC group) or without PolyPHb (STS group), then subjected to I/R injury. Our results showed that PolyPHb pretreatment greatly reduced the TUNEL-positive myocardial cells and decreased the caspase-3 activity and cleavage, which was further confirmed by the linear regression analysis. Therefore, PolyPHb pretreatment was beneficial to attenuation of myocardial apoptosis and provided protection to the heart against I/R injury.

Protective effects of hemoglobin-based oxygen carrier given to isolated heart during ischemia via attenuation of mitochondrial oxidative damage

Ischemia/reperfusion (I/R) injury is harmful to the cardiovascular system and responsible for mitochondrial oxidative stress, which will in turn aggravate cardiac dysfunction. This study was designed to investigate the protective effect of a hemoglobin-based oxygen carrier (HBOC) on I/R heart and to elucidate the potential mechanism. Isolated Sprague-Dawley rat hearts were perfused in Langendorff mode. After 30-min basal perfusion, warm ischemia (37 degrees C) or hypothermic storage (4 degrees C) was performed and followed by 2-h reperfusion. The results of our study reveal that HBOC provides a profound protection against cardiac I/R injury as evidenced by significantly improved cardiac function and decreased myocardial infarction, necrosis, and apoptosis. In addition to more oxygen supply to the myocardium, the cardioprotection of HBOC was closely related to well-preserved mitochondrial redox potential, significantly elevated mitochondrial superoxide dismutase activity, and decreased mitochondrial hydrogen peroxide and malondialdehyde formation, which indicated that the I/R-induced mitochondrial oxidative damage was remarkably attenuated. Furthermore, the elevated mitochondrial function and unchanged mitochondrial structure provide additional evidence of the prominent role of HBOC in mitochondrial preservation. In conclusion, our results demonstrate the cardioprotective effect of HBOC on I/R heart and reveal that this protection was mediated in large part by attenuation of mitochondrial oxidative damage.