Nitric oxide and cardiobiology-methods for intact hearts and isolated myocytes

Immune response differences in degradable and non-degradable alloy implants

Alloy based implants have made a great impact in the clinic and in preclinical research. Immune responses are one of the major causes of failure of these implants in the clinic. Although the immune responses toward non-degradable alloy implants are well documented, there is a poor understanding of the immune responses against degradable alloy implants. Recently, there have been several reports suggesting that degradable implants may develop substantial immune responses. This phenomenon needs to be further studied in detail to make the case for the degradable implants to be utilized in clinics. Herein, we review these new recent reports suggesting the role of innate and potentially adaptive immune cells in inducing immune responses against degradable implants. First, we discussed immune responses to allergen components of non-degradable implants to give a better overview on differences in the immune response between non-degradable and degradable implants. Furthermore, we also provide potential areas of research that can be undertaken that may shed light on the local and global immune responses that are generated in response to degradable implants.

Stimulation of Akt Phosphorylation and Glucose Transport by Metalloporphyrins with Peroxynitrite Decomposition Catalytic Activity

Iron porphyrin molecules such as hemin and iron(III) 4,4′,4″,4‴-(porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) (FeTBAP) have previously been shown to influence insulin signaling and glucose metabolism. We undertook this study to determine whether a catalytic action of iron porphyrin compounds would be related to their stimulation of insulin signaling and glucose uptake in C2C12 myotubes. FeTBAP did not display nitrite reductase activity or alter protein S-nitrosylation in myotubes, eliminating this as a candidate mode by which FeTBAP could act. FeTBAP displayed peroxynitrite decomposition catalytic activity in vitro. Additionally, in myotubes FeTBAP decreased protein nitration. The peroxynitrite decomposition catalyst Fe(III)5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato chloride (FeTPPS) also decreased protein nitration in myotubes, but the iron porphyrin Fe(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachlorideporphyrin pentachloride (FeTMPyP) did not. FeTBAP and FeTPPS, but not FeTMPyP, showed in vitro peroxidase activity. Further, FeTBAP and FeTPPs, but not FeTMPyP, increased Akt phosphorylation and stimulated glucose uptake in myotubes. These findings suggest that iron porphyrin compounds with both peroxynitrite decomposition activity and peroxidase activity can stimulate insulin signaling and glucose transport in skeletal muscle cells.

Adrenomedullin protects rat dorsal root ganglion neurons against doxorubicin-induced toxicity by ameliorating oxidative stress

OBJECTIVES

Despite effective anticancer effects, the use of doxorubicin (DOX) is hindered due to its cardio and neurotoxicity. The neuroprotective effect of adrenomedullin (AM) was shown in several studies. The present study aimed to evaluate the possible protective effects of AM against DOX-induced toxicity in dorsal root ganglia (DRGs) neurons.

MATERIALS AND METHODS

Rat embryonic DRG neurons were isolated and cultured. The effect of various concentrations of DOX (0.0 to 100 µM) in the absence or presence of AM (3.125 -100 nM) on cell death, apoptosis, oxidative stress, expression of tumor necrosis-α (TNF-α), interleukin1- β (IL-1β), inducible nitric oxide synthase (iNOS), matrix metalloproteinase (MMP) 3 and 13, and SRY-related protein 9 (SOX9) were examined.

RESULTS

Based on MTT assay data, DOX decreased the viability of DRG neurons in a dose and time-dependent manner (IC50=6.88 µm) while dose-dependently, AM protected DRG neurons against DOX-induced cell death. Furthermore, results of annexin V apoptosis assay revealed the protective effects of AM (25 nm) against DOX (6.88 µM)-induced apoptosis and necrosis of DRG neurons. Also, AM significantly ameliorated DOX-induced oxidative stress in DRG neurons. Real-time PCR results showed a significant increase in the expression of TNF-α, IL-1β, iNOS, MMP 3, and MMP 13, and a decrease in the expression of SOX9 following treatment with DOX. Treatment with AM (25 nM) significantly reversed the effects of DOX on the above-mentioned genes expression.

CONCLUSION

Our findings suggest that AM can be considered a novel ameliorating drug against DOX-induced neurotoxicity.

Cardiac stem cells: biology and clinical applications

SIGNIFICANCE

Heart disease is the primary cause of death in the industrialized world. Cardiac failure is dictated by an uncompensated reduction in the number of viable and fully functional cardiomyocytes. While current pharmacological therapies alleviate the symptoms associated with cardiac deterioration, heart transplantation remains the only therapy for advanced heart failure. Therefore, there is a pressing need for novel therapeutic modalities. Cell-based therapies involving cardiac stem cells (CSCs) constitute a promising emerging approach for the replenishment of the lost tissue and the restoration of cardiac contractility.

RECENT ADVANCES

CSCs reside in the adult heart and govern myocardial homeostasis and repair after injury by producing new cardiomyocytes and vascular structures. In the last decade, different classes of immature cells expressing distinct stem cell markers have been identified and characterized in terms of their growth properties, differentiation potential, and regenerative ability. Phase I clinical trials, employing autologous CSCs in patients with ischemic cardiomyopathy, are being completed with encouraging results.

CRITICAL ISSUES

Accumulating evidence concerning the role of CSCs in heart regeneration imposes a reconsideration of the mechanisms of cardiac aging and the etiology of heart failure. Deciphering the molecular pathways that prevent activation of CSCs in their environment and understanding the processes that affect CSC survival and regenerative function with cardiac pathologies, commonly accompanied by alterations in redox conditions, are of great clinical importance.

FUTURE DIRECTIONS

Further investigations of CSC biology may be translated into highly effective and novel therapeutic strategies aiming at the enhancement of the endogenous healing capacity of the diseased heart.

Exogenous intravascular nitric oxide enhances ventricular function after hemodilution with plasma expander

AIMS

This study evaluated the hypothesis that exogenous nitric oxide (NO) supplementation during acute hemodilution with plasma expander (PE) provides beneficial effects on cardiac function.

MAIN METHODS

Acute hemodilution in golden Syrian hamsters was induced by a 40% of blood volume exchange with dextran 70 kDa. Intravascular NO supplementation after hemodilution was accomplished with a NO donor, diethylenetriamine NONOate (DETA NONOate). The test group was treated with DETA NONOate, while the control group received only vehicle. Left ventricular cardiac function was studied using pressure-volume measurements obtained with a miniaturized conductance catheter.

KEY FINDINGS

Cardiac output increased to 122±5% and 107±1% of the baseline in the group treated with NO donor and the vehicle group, respectively. Stroke work per stroke volume (SW/SV) after hemodilution reduced to 90% of the baseline and the NO donor significantly reduced SW/SV compared to the vehicle. The minimum rate of pressure change (dP/dt(min)) was significantly lower in animals treated with the NO donor compared to vehicle treated animals. Systemic vascular resistance (SVR) decreased to 62±5% of the baseline in the NO donor group whereas the vehicle group SVR decreased to 83±5% of the baseline. Using intravital microscopy analysis of microvessel in the dorsal skinfold window chamber, we established that the NO donor group induced significant vasodilation compared to the vehicle group.

SIGNIFICANCE

NO supplementation in an acute hemodilution with PE has beneficial effects on cardiac performance. However, the NO supplementation effects with a NO donor are dose-independent and short-lasting.

Proteome reference map and regulation network of neonatal rat cardiomyocyte

AIM

To study and establish a proteome reference map and regulation network of neonatal rat cardiomyocyte.

METHODS

Cultured cardiomyocytes of neonatal rats were used. All proteins expressed in the cardiomyocytes were separated and identified by two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Biological networks and pathways of the neonatal rat cardiomyocytes were analyzed using the Ingenuity Pathway Analysis (IPA) program (www.ingenuity.com). A 2-DE database was made accessible on-line by Make2ddb package on a web server.

RESULTS

More than 1000 proteins were separated on 2D gels, and 148 proteins were identified. The identified proteins were used for the construction of an extensible markup language-based database. Biological networks and pathways were constructed to analyze the functions associate with cardiomyocyte proteins in the database. The 2-DE database of rat cardiomyocyte proteins can be accessed at http://2d.bjmu.edu.cn.

CONCLUSION

A proteome reference map and regulation network of the neonatal rat cardiomyocytes have been established, which may serve as an international platform for storage, analysis and visualization of cardiomyocyte proteomic data.

First aid kit for hypoxic survival: sensors and strategies

Survival success under conditions of acute oxygen deprivation depends on efficiency of the central and peripheral chemoreception, optimization of oxygen extraction from the hypoxic environment and its delivery to the periphery, and adjustments of energy production and consumption. This article uses a comparative approach to assess the efficiency of adaptive strategies used by anoxia-tolerant and hypoxia-sensitive species to support survival during the first minutes to 1 h of oxygen deprivation. An aquatic environment is much more demanding in terms of diurnal and seasonal variations of the ambient oxygen availability from anoxia to hyperoxia than is an air environment. Therefore, fishes and aquatic turtles have developed a number of adaptive responses, which are lacking in most of the terrestrial mammals, to cope with these extreme conditions. These include efficient central and peripheral chemoreception, acute changes in respiratory rate and amplitude, and acute increase of the gas-exchange interface. A special set of adaptive mechanisms are engaged in reduction of the energy expenditure of the major oxygen-consuming organs: the brain and the heart. Both reduction of ATP consumption and a switch to alterative energy sources contribute to the maintenance of ATP and ion balance in hypoxia-tolerant animals. Hypoxia and hyperoxia are conditions favoring development of oxidative stress. Efficient protection from oxidation in anoxia-tolerant species includes reduction in the glutamate levels in the brain, stabilization of the mitochondrial function, and maintenance of nitric oxide production under conditions of oxygen deprivation. We give an overview of the current state of knowledge on some selected molecular and cellular acute adaptive mechanisms. These include the mechanisms of chemoreception in adult and neonatal mammals and in fishes, acute metabolic adaptive responses in the brain, and the role of nitrite in the preservation of heart function under hypoxic conditions.

Protein S-nitrosylation and cardioprotection

Nitric oxide (NO) plays an important role in the regulation of cardiovascular function. In addition to the classic NO activation of the cGMP-dependent pathway, NO can also regulate cell function through protein S-nitrosylation, a redox dependent, thiol-based, reversible posttranslational protein modification that involves attachment of an NO moiety to a nucleophilic protein sulfhydryl group. There are emerging data suggesting that S-nitrosylation of proteins plays an important role in cardioprotection. Protein S-nitrosylation not only leads to changes in protein structure and function but also prevents these thiol(s) from further irreversible oxidative/nitrosative modification. A better understanding of the mechanism regulating protein S-nitrosylation and its role in cardioprotection will provide us new therapeutic opportunities and targets for interventions in cardiovascular diseases.

Posttranslational glutathiolation of aldose reductase (AKR1B1): a possible mechanism of protein recovery from S-nitrosylation

Nitric oxide (NO) is an important regulator of the catalytic activity of aldose reductase (AR). It reacts with the active site cysteines of AR and this reaction results in the formation of several kinetically distinct forms of the protein. The catalytic activity of AR is increased in the ischemic heart and this increase in activity is associated with NO-dependent modification of AR. During reperfusion, the enzyme reverts back to its un-activated form. Although, AR activation has been linked to thiol oxidation, the mechanisms of de-activation remain unclear. Here we report that treatment of recombinant human AR (AKR1B1) by a non-thiol-based NO-donor (DEANO) results in activation and S-nitrosylation of the protein. The nitrosylated (ARSNO), but not the reduced (ARSH), protein reacted with reduced glutathione (GSH) and this reaction resulted in the formation of glutathiolated AR (ARSSG). The modification of AR by NO was site-specific at Cys-298 and was not affected by selective mutation of the neighboring residue, Cys-303 to an alanine. Incubation of the glutathiolated AR (ARSSG) with GSH resulted in the regeneration of the reduced form of the protein (ARSH). Treatment of nitrosylated AR (ARSNO) with ascorbic acid also led to the conversion of the protein to its reduced form. These observations suggest that intracellular reductants such as GSH and ascorbate could convert the nitrosylated form of AR to its basal or reduced state. In general, such reductive reactions might represent a common mechanism for denitrosylating proteins or an "off" switch in NO-mediated signaling pathways involving protein S-nitrosylation reactions.