Pyruvate improves redox status and decreases indicators of hepatic apoptosis during hemorrhagic shock in swine

Effects of unpredictable chronic mild stress on the cellular redox state and mitochondrial energy homeostasis in rat adipose tissue: A comprehensive metabolic study

Unpredictable chronic mild stress (UCMS) leads to variable metabolic effects. Oxidative stress (OS) of adipose tissue (AT) and mitochondrial energy homeostasis is little investigated. This work studied the effects of UCMS on OS and the antioxidant/redox status in AT and mitochondrial energy homeostasis in rats. Twenty-four male Wistar rats (180-220 g) were divided into two equal groups; the normal control (NC) group and the UCMS group which were exposed to various stresses for 28 days. An indirect calorimetry machine was used to measure volumes of respiratory gases (VO2 & VCO2 ), total energy expenditure (TEE), and food intake (FI). The AT depots were collected, weighed, and used for measuring activities and gene expression of key antioxidant enzymes (GPx1, SOD, CAT, GR, GCL, and GS), OS marker levels including superoxide anion (SA), peroxynitrite radical (PON), nitric oxide (NO), hydrogen peroxide (H2 O2 ), lipid peroxides (LPO), t-protein carbonyl content (PCC), and reduced/oxidized glutathione levels (GSH, GSSG). Additionally, AT mitochondrial fractions were used to determine the activities of the tricarboxylic acid cycle (TCA) cycle enzymes (CS, α-KGDH, ICDH, SDH, MDH), respiratory chain complexes I-III, II-III, IV, the nicotinamide coenzymes NAD+ , NADH, and ATP/ADP levels. Compared with the NC group, the UCMS group showed very significantly increased OS marker levels, lowered antioxidant enzyme activities and gene expression, as well as lowered TCA cycle and respiratory chain activity and NAD+ , NADH, and ATP levels (p < .001 for all comparisons). Besides, the UCMS group had lowered TEE and insignificant FI and weight gain. In conclusion, AT of the UCMS-subjected rats showed a state of disturbed redox balance linked to disrupted energy homeostasis producing augmentation of AT.

Oral pyruvate prevents high-intensity interval exercise-induced metabolic acidosis in rats by promoting lactate dehydrogenase reaction

Introduction

There is no denying the clinical benefits of exogenous pyruvate in the treatment of pathological metabolic acidosis. However, whether it can prevent exercise physiological metabolic acidosis, delay the occurrence of exercise fatigue, and improve the beneficial effects of exercise and its internal mechanism remain unclear.

Methods

We randomly divided 24 male SD rats into 3 groups: one group was a control without exercise (CC, n = 8), and the other two groups were supplemented with 616 mg/kg/day pyruvate (EP, n = 8) or distilled water of equal volume (EC, n = 8). These groups completed acute high-intensity interval exercise (HIIE) after 7 days of supplementation. The acid metabolism variables were measured immediately after exercise including blood pH (pH_e), base excess (BE), HCO₃ ^-, blood lactic acid and skeletal muscle pH (pH_i). The redox state was determined by measuring the oxidized coenzyme I/reduced coenzyme I (nicotinamide adenine dinucleotide [NAD⁺]/reduced NAD⁺ [NADH]) ratio and lactate/pyruvate (L/P) ratio. In addition, the activities of lactate dehydrogenase A (LDHA), hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK) were determined by ELISA.

Results

Pyruvate supplementation significantly reversed the decrease of pHe, BE, HCO₃ ^- and pH_i values after HIIE (p < 0.001), while significantly increased the activities of LDHA (p = 0.048), HK (p = 0.006), and PFK (p = 0.047). Compared with the CC, the NAD+/NADH (p = 0.008) ratio and the activities of LDHA (p = 0.002), HK (p < 0.001), PFK (p < 0.001), and PK (p = 0.006) were significantly improved in EP group.

Discussion

This study provides compelling evidence that oral pyruvate attenuates HIIE-induced intracellular and extracellular acidification, possibly due to increased activity of LDHA, which promotes the absorption of H⁺ in the LDH reaction. The beneficial effects of improving the redox state and glycolysis rate were also shown. Our results suggest that pyruvate can be used as an oral nutritional supplement to buffer HIIE induced metabolic acidosis.

A Novel Therapeutic Approach With Sodium Pyruvate on Vital Signs, Acid–Base, and Metabolic Disturbances in Rats With a Combined Blast and Hemorrhagic Shock

Background

Blast injuries from improvised explosive devices (IEDs) are known to cause blast traumatic brain injuries (bTBIs), hemorrhagic shock (HS), organ damage, mitochondrial dysfunction, and subsequent free radical production. A pre-citric acid cycle reagent, pyruvate, is suggested to improve mitochondrial ATP production through the activation of the mitochondrial gatekeeper enzyme “pyruvate dehydrogenase complex (PDH).” Our study aimed to investigate the role of physiologic, metabolic, and mitochondrial effects of hypertonic sodium pyruvate resuscitation in rats with a combined blast and HS injury.

Methods

A pre-clinical rat model of combined injury with repetitive 20 PSI blast exposure accompanied with HS and fluid resuscitation (sodium pyruvate as metabolic adjuvant or hypertonic saline as control), followed by transfusion of shed blood was used in this study. Control sham animals (instrumental and time-matched) received anesthesia and cannulation, but neither received any injury nor treatment. The mean arterial pressure and heart rate were recorded throughout the experiment by a computerized program. Blood collected at T0 (baseline), T60 (after HS), and T180 (end) was analyzed for blood chemistry and mitochondrial PDH enzyme activity.

Results

Sodium pyruvate resuscitation significantly improved the mean arterial pressure (MAP), heart rate (HR), pulse pressure (PP), hemodynamic stability (Shock index), and autonomic response (Kerdo index) after the HS and/or blast injury. Compared with the baseline values, plasma lactate and lactate/pyruvate ratios were significantly increased. In contrast, base excess BE/(HCO3-) was low and the pH was also acidotic <7.3, indicating the sign of metabolic acidosis after blast and HS in all animal groups. Sodium pyruvate infusion significantly corrected these parameters at the end of the experiment. The PDH activity also improved after the sodium pyruvate infusion.

Conclusion

In our rat model of a combined blast and HS injury, hypertonic sodium pyruvate resuscitation was significantly effective in hemodynamic stabilization by correcting the acid–base status and mitochondrial mechanisms via its pyruvate dehydrogenase enzyme.

Protection from systemic pyruvate at resuscitation in newborn lambs with asphyxial cardiac arrest

BACKGROUND

Infants with hypoxic-ischemic injury often require cardiopulmonary resuscitation. Mitochondrial failure to generate adenosine triphosphate (ATP) during hypoxic-ischemic reperfusion injury contributes to cellular damage. Current postnatal strategies to improve outcome in hypoxic-ischemic injury need sophisticated equipment to perform servo-controlled cooling. Administration of intravenous pyruvate, an antioxidant with favorable effects on mitochondrial bioenergetics, is a simple intervention that can have a global impact. We hypothesize that the administration of pyruvate following the return of spontaneous circulation (ROSC) would improve cardiac function, systemic hemodynamics, and oxygen utilization in the brain in newborn lambs with cardiac arrest (CA).

METHODS

Term lambs were instrumented, delivered by C-section and asphyxia induced by umbilical cord occlusion along with clamping of the endotracheal tube until asystole; Lambs resuscitated following 5 min of CA; upon ROSC, lambs were randomized to receive pyruvate or saline infusion over 90 min and ventilated for 150 min postinfusion. Pulmonary and systemic hemodynamics and arterial gases monitored. We measured plasma pyruvate, tissue lactate, and ATP levels (heart and brain) in both groups.

RESULTS

Time to ROSC was not different between the two groups. Systolic and diastolic blood pressures, stroke volume, arterial oxygen content, and cerebral oxygen delivery were similar between the two groups. The cerebral metabolic rate of oxygen was higher following pyruvate infusion; higher oxygen consumption in the brain was associated with lower plasma levels but higher brain ATP levels compared to the saline group.

CONCLUSIONS

Pyruvate promotes energy generation accompanied by efficient oxygen utilization in the brain and may facilitate additional neuroprotection in the presence of hypoxic-ischemic injury.

Effect of peritoneal dialysis solution with different pyruvate concentrations on intestinal injury

To investigate the effects of direct peritoneal resuscitation with pyruvate-peritoneal dialysis solution (Pyr-PDS) of different concentrations combined with intravenous resuscitation on acid–base imbalance and intestinal ischemia reperfusion injury in rats with hemorrhagic shock. Sixty rats were randomly assigned to group SHAM, group intravenous resuscitation, and four direct peritoneal resuscitation groups combined with intravenous resuscitation: group NS, LA, PY1, and PY2, that is, normal saline, lactate-PDS (Lac-PDS), lower concentration Pyr-PDS (Pyr-PDS1), and higher concentration Pyr-PDS (Pyr-PDS2), respectively. Two hours after hemorrhagic shock and resuscitation, the pH, oxygen partial pressure, carbon dioxide partial pressure (PCO2), base excess, and bicarbonate ion concentration (HCO3−) of the arterial blood were measured. The intestinal mucosal damage index and intercellular adhesion molecule 1 (ICAM-1), tumor necrosis factor-α, interleukin-6, zonula occludens-1, claudin-1, and occludin levels in intestinal issues were detected. Two hours after resuscitation, group PY2 had higher mean arterial pressure, pH, oxygen partial pressure, and base excess and lower PCO2of arterial blood than group PY1 ( P <  0.05). Tumor necrosis factor-α and interleukin-6 levels in group PY2 were significantly lower than those in group PY1 ( P <  0.05). Zonula occludens-1, claudin-1, and occludin expression levels were significantly higher in group PY2 than in group PY1 ( P <  0.05). Direct peritoneal resuscitation with Pyr-PDS2 combined with intravenous resuscitation enhanced the hemodynamics, improved the acid–base balance, and alleviated intestinal ischemia reperfusion injury from hemorrhagic shock and resuscitation in rats. The mechanisms might include correction of acidosis, inhibition of inflammatory response, enhancement of systemic immune status, regulation of intestinal epithelial permeability, and maintenance of intestinal mucosal barrier function.

Impact statement

Hemorrhagic shock is a life-threatening condition after trauma or during surgery. Acid–base imbalance and intestinal ischemia reperfusion injury are two significant causes in the pathogenetic process and multiple organ dysfunction. As a result, it is urgent and necessary to find an effective method of resuscitation in order to reverse the acid–base imbalance and protect organ function. This current study confirmed the protection against hypoxic acidosis and intestinal ischemia reperfusion injury by peritoneal resuscitation with pyruvate combined with intravenous resuscitation in rats with hemorrhagic shock. And the peritoneal dialysis solution with pyruvate of high concentration plays a crucial role in the process. It provided a new idea and possible direction of fluid resuscitation for alleviating organ injuries, protecting organ functions, and improving clinical prognosis after hemorrhagic shock and resuscitation.

Exogenous pyruvate facilitates ultraviolet B-induced DNA damage repair by promoting H3K9 acetylation in keratinocytes and melanocytes

Ultraviolet radiation (UVR) is the major cause of numerous skin diseases, including sunburn, skin aging, and skin cancers. Pyruvate is a key intermediate in cellular metabolic pathways, which has shown protective effects against oxidative stress and apoptosis, but its role in UV protection remains unclear. Here we established human and mice in vivo model and found that pyruvate protects both human and mouse skin from UVB-induced DNA damage. Moreover, assays in primary keratinocytes and melanocytes further supported the protective role of exogenous pyruvate against UVB-induced DNA damage. Mechanically, pyruvate stimulates the activation of Histone H3 Lysine 9 (H3K9) acetylation, which is an essential step for nucleotide excision repair (NER) pathway. In conclusion, our results suggest that treatment of pyruvate might be an effective strategy to prevent UVB-induced skin diseases.

Insights from ion mobility-mass spectrometry, infrared spectroscopy, and molecular dynamics simulations on nicotinamide adenine dinucleotide structural dynamics: NAD+vs. NADH

Nicotinamide adenine dinucleotide (NAD) is found in all living cells where the oxidized (NAD⁺) and reduced (NADH) forms play important roles in many enzymatic reactions. However, little is known about NAD⁺ and NADH conformational changes and kinetics as a function of the cell environment. In the present work, an analytical workflow is utilized to study NAD⁺ and NADH dynamics as a function of the organic content in solution using fluorescence lifetime spectroscopy and in the gas-phase using trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS) and infrared multiple photon dissociation (IRMPD) spectroscopy. NAD solution time decay studies showed a two-component distribution, assigned to changes from a "close" to "open" conformation with the increase of the organic content. NAD gas-phase studies using nESI-TIMS-MS displayed two ion mobility bands for NAD⁺ protonated and sodiated species, while four and two ion mobility bands were observed for NADH protonated and sodiated species, respectively. Changes in the mobility profiles were observed for NADH as a function of the starting solution conditions and the time after desolvation, while NAD⁺ profiles showed no dependence. IRMPD spectroscopy of NAD⁺ and NADH protonated species in the 800-1800 and 3200-3700 cm^-1 spectral regions showed common and signature bands between the NAD forms. Candidate structures were proposed for NAD⁺ and NADH kinetically trapped intermediates of the protonated and sodiated species, based on their collision cross sections and IR profiles. Results showed that NAD⁺ and NADH species exist in open, stack, and closed conformations and that the driving force for conformational dynamics is hydrogen bonding of the N-H-O and O-H-O forms with ribose rings.

Efficacy of exogenous pyruvate in TremblerJ mouse model of Charcot-Marie-Tooth neuropathy

INTRODUCTION

Classic Charcot-Marie-Tooth (CMT) neuropathies including those with Schwann cell genetic defects exhibit a length-dependent process affecting the distal axon. Energy deprivation in the distal axon has been the proposed mechanism accounting for length-dependent distal axonal degeneration. We hypothesized that pyruvate, an intermediate glycolytic product, could restore nerve function, supplying lost energy to the distal axon.

METHODS

To test this possibility, we supplied pyruvate to the drinking water of the Trembler-J (TrJ ) mouse and assessed efficacy based on histology, electrophysiology, and functional outcomes. Pyruvate outcomes were compared with untreated TrJ controls alone or adeno-associated virus mediated NT-3 gene therapy (AAV1.NT-3)/pyruvate combinatorial approach.

RESULTS

Pyruvate supplementation resulted increased myelinated fiber (MF) densities and myelin thickness in sciatic nerves. Combining pyruvate with proven efficacy from AAV1.tMCK.NT-3 gene therapy provided additional benefits showing improved compound muscle action potential amplitudes and nerve conduction velocities compared to pyruvate alone cohort. The end point motor performance of both the pyruvate and the combinatorial therapy cohorts was better than untreated TrJ controls. In a unilateral sciatic nerve crush paradigm, pyruvate supplementation improved myelin-based outcomes in both regenerating and the contralateral uncrushed nerves.

CONCLUSIONS

This proof of principle study demonstrates that exogenous pyruvate alone or as adjunct therapy in TrJ may have clinical implications and is a candidate therapy for CMT neuropathies without known treatment.

Expression of genes encoding the luciferase from Photobacterium leiognathi in Escherichia coli Rosetta (DE3) and its application in NADH detection

Cloning of genes encoding the luciferase from Photobacterium leiognathi YL in Escherichia coli Rosetta (DE3) was performed successfully and the expressed forms of lux AB were purified to homogeneity. Experimental measurements revealed that luciferase from Photobacterium leiognathi YL has good thermal stability and a high residual activity at extreme pH values, which are extremely important for its various ecological, industrial and medical applications. Furthermore, we made a first attempt for quantitative detection of NADH by recombinant E. coli Rosetta (DE3) coupled enzyme system. A good linear relationship between luminescence intensity and NADH with low (1-12 nmol/L) and high (10-500 nmol/L) concentration was observed, whose standard curve was y = 772.97× + 4041.1, R²  = 0.9884 and y = 1710× + 4.99 × 10⁵ , R²  = 0.9727, respectively. Our results demonstrate a high sensitivity of recombinant E. coli coupled enzyme system to NADH on the basis of high soluble expression of recombinant luciferase and continuous and stable expression of some NAD(P)H-dependent flavin mononucleotide (FMN) reductases.

Roles of nitric oxide and ethyl pyruvate after peripheral nerve injury

Short-lived reactive nitrogen species and reactive oxygen species have acquired significant attention in the field of biomedical science. Nitric oxide (NO), which was thought to be an unstable gas and pollutant, is now regarded as a gas transmitter like H2S and CO. NO is synthesized inside the mammalian body by l-arginine via three different isoforms of NO synthase whereas pyruvate is a glycolysis product and substrate for TCA cycle. Due to poor solubility and stability, therapeutic potential of pyruvate is limited. Ethyl pyruvate (EP) is now considered as a suitable replacement of pyruvate. In this paper, we will try to focus the effect of NO and EP in Schwann cell dedifferentiation, proliferation, nerve degeneration, and regeneration during Wallerian degeneration (WD) of peripheral nerve injury along with their neuroprotective effects, cardiovascular functioning, support in hepatic complication, etc.

Anti-apoptotic and myocardial protective effects of ethyl pyruvate after regional ischaemia/reperfusion myocardial damage in an in vivo rat model

INTRODUCTION

The integration of reactive oxygen species is strongly associated with important pathophysiological mechanisms that mediate myocardial ischaemia/reperfusion (I/R) damage. Pyruvate is an efficacious scavenger of reactive oxygen species and a previous study has shown that ethyl pyruvate (EP) has a myocardial protective effect against regional I/R damage in an in vivo rat model. The purpose of this study was to determine whether the myocardial protective effect of EP is associated with anti-apoptosis.

METHODS

Rats were allocated to receive EP dissolved in lactated Ringer's solution or lactated Ringer's solution alone, via intraperitoneal infusion one hour before ischaemia. They were exposed to 30 minutes of ischaemia followed by reperfusion of the left coronary artery territory over two hours. Anti-apoptotic effects were checked using several biochemical parameters after two hours of reperfusion. Apoptosis was analysed using measured caspase-3 activity, Western blotting of B-cell lymphoma 2 (Bcl-2) family protein cleaved by caspase-3, and assessment of DNA laddering patterns and the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining test.

RESULTS

In ischaemic myocardium, EP increased Bcl-2 expression, but reduced Bcl-2-associated X protein and cleaved caspase-3 expressions. EP reduced the expression of DNA laddering and the number of myocardial I/R-damaged TUNEL-positive cells.

CONCLUSION

This study demonstrated that EP has an anti-apoptotic effect after regional I/R damage in an in vivo rat heart model. The myocardial protective effect of EP may be related to its anti-apoptotic effect.

Pyruvate treatment attenuates cerebral metabolic depression and neuronal loss after experimental traumatic brain injury

Experimental traumatic brain injury (TBI) is known to produce an acute increase in cerebral glucose utilization, followed rapidly by a generalized cerebral metabolic depression. The current studies determined effects of single or multiple treatments with sodium pyruvate (SP; 1000mg/kg, i.p.) or ethyl pyruvate (EP; 40mg/kg, i.p.) on cerebral glucose metabolism and neuronal injury in rats with unilateral controlled cortical impact (CCI) injury. In Experiment 1 a single treatment was given immediately after CCI. SP significantly improved glucose metabolism in 3 of 13 brain regions while EP improved metabolism in 7 regions compared to saline-treated controls at 24h post-injury. Both SP and EP produced equivalent and significant reductions in dead/dying neurons in cortex and hippocampus at 24h post-CCI. In Experiment 2 SP or EP were administered immediately (time 0) and at 1, 3 and 6h post-CCI. Multiple SP treatments also significantly attenuated TBI-induced reductions in cerebral glucose metabolism (in 4 brain regions) 24h post-CCI, as did multiple injections of EP (in 4 regions). The four pyruvate treatments produced significant neuroprotection in cortex and hippocampus 1day after CCI, similar to that found with a single SP or EP treatment. Thus, early administration of pyruvate compounds enhanced cerebral glucose metabolism and neuronal survival, with 40mg/kg of EP being as effective as 1000mg/kg of SP, and multiple treatments within 6h of injury did not improve upon outcomes seen following a single treatment.

Pyruvate dose response studies targeting the vital signs following hemorrhagic shock

Objectives:

To determine the optimal effective dose of sodium pyruvate in maintaining the vital signs following hemorrhagic shock (HS) in rats.

Materials and Methods:

Anesthetized, male Sprague-Dawley rats underwent computer-controlled HS for 30 minute followed by fluid resuscitation with either hypertonic saline, or sodium pyruvate solutions of 0.5 M, 1.0 M, 2.0 M, and 4.0 M at a rate of 5ml/kg/h (60 minute) and subsequent blood infusion (60 minute). The results were compared with sham and non- resuscitated groups. The animals were continuously monitored for mean arterial pressure, systolic and diastolic pressure, heart rate, pulse pressure, temperature, shock index and Kerdo index (KI).

Results:

The Sham group remained stable throughout the experiment. Non-resuscitated HS animals did not survive for the entire experiment due to non-viable vital signs and poor shock and KI. All fluids were effective in normalizing the vital signs when shed blood was used adjunctively. Sodium pyruvate 2.0 M was most effective, and 4.0 M solution was least effective in improving the vital signs after HS.

Conclusions:

Future studies should be directed to use 2.0 M sodium pyruvate adjuvant for resuscitation on multiorgan failure and survival rate in HS.

The effect of Walterinnesia aegyptia venom proteins on TCA cycle activity and mitochondrial NAD(+)-redox state in cultured human fibroblasts

Fibroblast cultures were used to study the effects of crude Walterinnesia aegyptia venom and its F1–F7 protein fractions on TCA cycle enzyme activities and mitochondrial NAD-redox state. Confluent cells were incubated with 10 μg of venom proteins for 4 hours at 37°C. The activities of all studied TCA enzymes and the non-TCA mitochondrial NADP⁺-dependent isocitrate dehydrogenase underwent significant reductions of similar magnitude (50–60% of control activity) upon incubation of cells with the crude venom and fractions F4, F5, and F7 and 60–70% for fractions F3 and F6. In addition, the crude and fractions F3–F7 venom proteins caused a drop in mitochondrial NAD⁺ and NADP⁺ levels equivalent to around 25% of control values. Whereas the crude and fractions F4, F5, and F7 venom proteins caused similar magnitude drops in NADH and NADPH (around 55% of control levels), fractions F3 and F6 caused a more drastic drop (60–70% of control levels) of both reduced coenzymes. Results indicate that the effects of venom proteins could be directed at the mitochondrial level and/or the rates of NAD⁺ and NADP⁺ biosynthesis.

Effects of sodium pyruvate on ameliorating metabolic acidosis

OBJECTIVE

To examine the effects of sodium pyruvate (SP) on metabolic acidosis.

METHODS

For the in vivo experiments, we evaluated effects of SP on an ammonium chloride (NH4Cl)-induced hyperchloremic acidosis rat model. SP was infused at overall doses of 2, 4, and 6 mmol·kg(- 1) for the SP1, SP2, and SP3 groups, respectively. Treatment with sodium bicarbonate (SB) was used as a positive control (2 mmol·kg(- 1)), and treatment with normal saline (NS) was used as a volume control (2 mL·kg(- 1)). Blood was sampled from the ophthalmic venous plexus for pH, blood gases, electrolytes, glucose, creatinine (Cr), and urea analysis after injection. For the in vitro experiment, propionate was applied to induce intracellular acidosis in human endothelial cells. Intracellular pH (pHi) was fluorimetrically measured after the addition of SP.

RESULTS

In the in vivo study, the pH of SP1 group showed no significant difference compared with that of the NS group. The SP2 and SP3 groups had a higher pH than the NS group (P < 0.01). The SP3 group had a higher pH than the SB group (P < 0.05) and SP1 group (P < 0.05). Moreover, SP treatment ameliorated the abnormality of calcium and decreased the blood potassium levels. The SP3 group had higher glucose levels than SP1 group (P < 0.05). No significant differences were observed between all the groups in the plasma Cr and urea levels. In the in vitro study, the pHi increased immediately after the addition of SP.

CONCLUSION

The data suggest that intravascular treatment with SP represents a novel therapeutic strategy to ameliorate metabolic acidosis.

Pyruvate-enriched resuscitation: metabolic support of post-ischemic hindlimb muscle in hypovolemic goats

Tourniquet-imposed ischemia-reperfusion of extremities generates reactive oxygen and nitrogen species (RONS), which can disrupt intermediary metabolism and ATP production. This study tested the hypothesis that fluid resuscitation with pyruvate, a natural antioxidant and metabolic fuel, ameliorates the deleterious effects of ischemia-reperfusion on intermediary metabolism in skeletal muscle. Anesthetized male goats (∼25 kg) were bled to a mean arterial pressure of 48 ± 1 mmHg and then subjected to 90 min hindlimb ischemia with a tourniquet and femoral crossclamp, followed by 4-h reperfusion. Lactated Ringers (LR) or pyruvate Ringers (PR) was infused intravenous for 90 min, from 30 min ischemia to 30 min reperfusion, to deliver 0.05 mmol kg(-1) min(-1) lactate or pyruvate. Time controls (TC) underwent neither hemorrhage nor hindlimb ischemia. Lipid peroxidation product 8-isoprostane, RONS-sensitive aconitase and creatine kinase activities, antioxidant superoxide dismutase activity, and phosphocreatine phosphorylation potential ([PCr]/[{Cr}{P(i)}]), an index of tissue energy state, were measured in reperfused gastrocnemius at 90 min resuscitation (n = 6 all groups) and 3.5 h post-resuscitation (n = 8 TC, 9 LR, 10 PR). PR more effectively than LR suppressed 8-isoprostane formation, prevented inactivation of aconitase and creatine kinase, doubled superoxide dismutase activity, and augmented [PCr]/([Cr][P(i)]). Pyruvate-enriched Ringer's is metabolically superior to Ringer's lactate for fluid resuscitation of tourniqueted muscle.

Pyruvate-fortified resuscitation stabilizes cardiac electrical activity and energy metabolism during hypovolemia

AIM: To test the hypothesis that fluid resuscitation with Ringer’s solution enriched with pyruvate (PR), a physiological antioxidant and energy substrate, affords protection of myocardial metabolism and electrophysiological performance superior to lactated Ringer’s (LR) during hypovolemia and hindlimb ischemia-reperfusion.

METHODS: Male domestic goats (25-30 kg) were exsanguinated to a mean arterial pressure of 48 ± 1 mmHg. Right hindlimb ischemia was imposed for 90 min by applying a tourniquet and femoral crossclamp. LR or PR, infused iv, delivered 0.05 mmol/kg per minute L-lactate or pyruvate, respectively, from 30 min hindlimb ischemia until 30 min post-ischemia. Time controls (TC) underwent neither hemorrhage, hindlimb ischemia nor resuscitation. Goats were sacrificed and left ventricular myocardium biopsied at 90 min fluid resuscitation (n = 6 per group) or 3.5 h later (n = 9 LR, 10 PR, 8 TC).

RESULTS: Myocardial 8-isoprostane content, phosphocreatine phosphorylation potential, creatine kinase activity, and heart rate-adjusted QT interval (QTc) variability were evaluated at 90 min resuscitation and 3.5 h post-resuscitation. PR sharply lowered pro-arrhythmic QTc variability vs LR (P < 0.05); this effect persisted 3.5 h post-resuscitation. PR lowered myocardial 8-isoprostane content, a product of oxidative stress, by 39 and 37% during and 3.5 h after resuscitation, respectively, vs LR. Creatine kinase activity fell 42% post-LR vs TC (P < 0.05), but was stable post-PR (P < 0.02 vs post-LR). PR doubled phosphocreatine phosphorylation potential, a measure of ATP free energy state, vs TC and LR (P < 0.05); this energetic enhancement persisted 3.5 h post-resuscitation.

CONCLUSION: By augmenting myocardial energy state and protecting creatine kinase activity, pyruvate-enriched resuscitation stabilized cardiac electrical function during central hypovolemia and hindlimb ischemia-reperfusion.

The role of anesthetic drugs in liver apoptosis

CONTEXT

The modern practice of anesthesia is highly dependent ona group of anesthetic drugs which many of them are metabolized in the liver.

EVIDENCE ACQUISITION

The liver, of course, usually tolerates this burden. However, this is not always an unbroken rule. Anesthetic induced apoptosis has gained great concern during the last years; especially considering the neurologic system.

RESULTS

However, we have evidence that there is some concern regarding their effects on the liver cells. Fortunately not all the anesthetics are blamed and even some could be used safely, based on the available evidence.

CONCLUSIONS

Besides, there are some novel agents, yet under research, which could affect the future of anesthetic agents' fate regarding their hepatic effects.

NAD+ metabolism and oxidative stress: the golden nucleotide on a crown of thorns

In the twentieth century, NAD+ research generated multiple discoveries. Identification of the important role of NAD+ as a cofactor in cellular respiration and energy production was followed by discoveries of numerous NAD+ biosynthesis pathways. In recent years, NAD+ has been shown to play a unique role in DNA repair and protein deacetylation. As discussed in this review, there are close interactions between oxidative stress and immune activation, energy metabolism, and cell viability in neurodegenerative disorders and ageing. Profound interactions with regard to oxidative stress and NAD+ have been highlighted in the present work. This review emphasizes the pivotal role of NAD+ in the regulation of DNA repair, stress resistance, and cell death, suggesting that NAD+ synthesis through the kynurenine pathway and/or salvage pathway is an attractive target for therapeutic intervention in age-associated degenerative disorders. NAD+ precursors have been shown to slow down ageing and extend lifespan in yeasts, and protect severed axons from degeneration in animal models neurodegenerative diseases.

The mitochondrial paradigm for cardiovascular disease susceptibility and cellular function: a complementary concept to Mendelian genetics

While there is general agreement that cardiovascular disease (CVD) development is influenced by a combination of genetic, environmental, and behavioral contributors, the actual mechanistic basis of how these factors initiate or promote CVD development in some individuals while others with identical risk profiles do not, is not clearly understood. This review considers the potential role for mitochondrial genetics and function in determining CVD susceptibility from the standpoint that the original features that molded cellular function were based upon mitochondrial-nuclear relationships established millions of years ago and were likely refined during prehistoric environmental selection events that today, are largely absent. Consequently, contemporary risk factors that influence our susceptibility to a variety of age-related diseases, including CVD were probably not part of the dynamics that defined the processes of mitochondrial-nuclear interaction, and thus, cell function. In this regard, the selective conditions that contributed to cellular functionality and evolution should be given more consideration when interpreting and designing experimental data and strategies. Finally, future studies that probe beyond epidemiologic associations are required. These studies will serve as the initial steps for addressing the provocative concept that contemporary human disease susceptibility is the result of selection events for mitochondrial function that increased chances for prehistoric human survival and reproductive success.

The redox basis of epigenetic modifications: from mechanisms to functional consequences

Epigenetic modifications represent mechanisms by which cells may effectively translate multiple signaling inputs into phenotypic outputs. Recent research is revealing that redox metabolism is an increasingly important determinant of epigenetic control that may have significant ramifications in both human health and disease. Numerous characterized epigenetic marks, including histone methylation, acetylation, and ADP-ribosylation, as well as DNA methylation, have direct linkages to central metabolism through critical redox intermediates such as NAD(+), S-adenosyl methionine, and 2-oxoglutarate. Fluctuations in these intermediates caused by both normal and pathologic stimuli may thus have direct effects on epigenetic signaling that lead to measurable changes in gene expression. In this comprehensive review, we present surveys of both metabolism-sensitive epigenetic enzymes and the metabolic processes that may play a role in their regulation. To close, we provide a series of clinically relevant illustrations of the communication between metabolism and epigenetics in the pathogenesis of cardiovascular disease, Alzheimer disease, cancer, and environmental toxicity. We anticipate that the regulatory mechanisms described herein will play an increasingly large role in our understanding of human health and disease as epigenetics research progresses.

Role of pyruvate dehydrogenase complex in traumatic brain injury and Measurement of pyruvate dehydrogenase enzyme by dipstick test

Objectives:

The present study was designed to investigate the role of a mitochondrial enzyme pyruvate dehydrogenase (PDH) on the severity of brain injury, and the effects of pyruvate treatment in rats with traumatic brain injury (TBI).

Methods:

We examined rats subjected to closed head injury using a fluid percussion device, and treated with sodium pyruvate (antioxidant and substrate for PDH enzyme). At 72 h post injury, blood was analyzed for blood gases, acid-base status, total PDH enzyme using a dipstick test and malondialdehyde (MDA) levels as a marker of oxidative stress. Brain homogenates from right hippocampus (injured area) were analyzed for PDH content, and immunostained hippocampus sections were used to determine the severity of gliosis and PDH E1-∞ subunit.

Results:

Our data demonstrate that TBI causes a significant reduction in PDH enzyme, disrupt-acid-base balance and increase oxidative stress in blood. Also, lower PDH enzyme in blood is related to the increased gliosis and loss of its PDH E1-∞ subunit PDH in brain tissue, and these effects of TBI were prevented by pyruvate treatment.

Conclusion:

Lower PDH enzyme levels in blood are related to the global oxidative stress, increased gliosis in brain, and severity of brain injury following TBI. These effects can be prevented by pyruvate through the protection of PDH enzyme and its subunit E-1.

Pyruvate-enriched cardioplegia suppresses cardiopulmonary bypass-induced myocardial inflammation

BACKGROUND

Cardiopulmonary bypass-induced oxidative stress initiates inflammation that can damage the myocardium. This study tested whether cardioplegia enriched with the intermediary metabolite and antioxidant pyruvate dampens postbypass myocardial inflammation.

METHODS

Pigs were maintained on cardiopulmonary bypass while their hearts were arrested for 60 minutes with 4:1 blood:crystalloid cardioplegia, in which the crystalloid contained 188 mM glucose ± 24 mM pyruvate. Pigs were weaned from bypass after 30 minutes of whole blood reperfusion and recovered for 4 hours. Glutathione (GSH) and glutathione disulfide (GSSG) were measured in coronary sinus plasma to indirectly monitor myocardial GSH redox state (GSH/GSSG). Left ventricular myocardium was sampled 4 hours after cardiopulmonary bypass for analyses of C-reactive protein, matrix metalloproteinases 2 and 9 and tissue inhibitor of metalloproteinase-2 (TIMP-2), and to assess neutrophil infiltration by histology and myeloperoxidase assay.

RESULTS

Coronary sinus GSH/GSSG fell 70% after cardiopulmonary bypass with control cardioplegia, but pyruvate cardioplegia produced a robust increase in coronary sinus GSH/GSSG that persisted for 4 hours after bypass. Myocardial C-reactive protein content increased 5.6-fold after control bypass, and neutrophil infiltration and myeloperoxidase activity also increased, but pyruvate-fortified cardioplegia prevented these inflammatory effects. Control cardioplegia lowered myocardial TIMP-2 content by 59% and increased matrix metalloproteinase-9 activity by 35% versus nonbypass sham values, but pyruvate cardioplegia increased TIMP-2 content ninefold versus control cardioplegia and prevented the increase in matrix metalloproteinase-9. Matrix metalloproteinase-2 was not affected by bypass ± pyruvate.

CONCLUSIONS

Pyruvate-enriched cardioplegia dampens cardiopulmonary bypass-induced myocardial inflammation. Increased GSH/GSSG and TIMP-2 may mediate pyruvate's effects.

Pyruvate attenuates cardiac dysfunction and oxidative stress in isoproterenol-induced cardiotoxicity

Pyruvate, a potent endogenous antioxidant and an important metabolic fuel is essential for the cardiac function and tissue defense mechanism. The present study was evaluated to investigate whether pyruvate attenuates the development of cardiotoxicity in isoproterenol (ISO)-induced myocardial infarction by assessing hemodynamic, biochemical and histopathological parameters. Subcutaneous injection of ISO (85 mg/kg) administered for 2 days at an interval of 24h was used for induction of cardiotoxicity. ISO administration significantly decreased arterial pressure indices, heart rate, contractility {(+)LVdP/dt} and relaxation {(-)LVdP/dt} and increased left ventricular end-diastolic pressure. In addition, a significant reduction in activities of myocardial creatine phosphokinase-MB, lactate dehydrogenase, superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione levels along with increase in thiobarbituric acid reactive substances were also observed following ISO administration. However, pretreatment with pyruvate (0.25, 0.5 and 1.0 g/kg, p.o.) favorably modulated all most every studied parameters in ISO-induced myocardial injury. Furthermore, protective effect of pyruvate was confirmed by histopathological studies. Rats pretreated only with pyruvate did not produce significant change in hemodynamic, biochemical and histopathological parameters. Pyruvate at 0.50 and 1.0 g/kg doses was found to exert optimal cardioprotective effect against ISO-induced myocardial infarction. The results of our study suggest that pyruvate possessing antioxidant activity has a significant cardioprotective effect against ISO-induced myocardial injury.

Hypertonic sodium pyruvate solution is more effective than Ringer's ethyl pyruvate in the treatment of hemorrhagic shock

Hypertonic sodium pyruvate (HSP), as well as ethyl pyruvate solutions, has been proposed as resuscitative fluids in the treatment of hemorrhagic shock (HS) because of their anti-inflammatory and antioxidant properties. The effectiveness of one pyruvate preparation over the other in the treatment of HS has not been evaluated. The authors aimed to compare two pyruvate solutions for resuscitation and their mechanisms of action in rats during HS. The effects of infusion of low-volume HSP were compared against high-volume Ringer's ethyl pyruvate on hemodynamic parameters, inflammatory cascade, and regulation of stress and apoptosis-related proteins in the liver. Sprague-Dawley rats were either treated as sham animals or subjected to computer-controlled arterial hemorrhage (40 mmHg) for 60 min followed by resuscitation with isotonic sodium chloride solution, hypertonic saline, Ringer's lactate solution, Ringer's ethyl pyruvate, or HSP for 60 min. Animals were continuously monitored for hemodynamic and biochemical parameters in blood. At the end of the experiment, animals were killed, and liver samples were taken for the evaluation of inflammatory and anti-inflammatory markers and mediators of oxidative stress, liver injury, and expression of apoptotic signaling proteins. In comparison with Ringer's ethyl pyruvate, HSP administration after hemorrhage reduced liver injury, which was associated with increased levels of serum and tissue inflammatory cytokines, inflammatory mediators such as NOS and cyclooxygenase 2, lipid peroxidation, and higher hepatocellular adenosine triphosphate. Cellular apoptotic events related to the activation of caspase-3 and poly(ADP-ribose)polymerase cleavage were also decreased by sodium pyruvate. Resuscitation with small-volume HSP offers significant protection against inflammatory and oxidative stress and in preventing liver injury compared with large-volume Ringer's ethyl pyruvate.

Metabolic and histologic effects of sodium pyruvate treatment in the rat after cortical contusion injury

This study determined the effects of intraperitoneal sodium pyruvate (SP) treatment on the levels of circulating fuels and on cerebral microdialysis levels of glucose (MD(glc)), lactate (MD(lac)), and pyruvate (MD(pyr)), and the effects of SP treatment on neuropathology after left cortical contusion injury (CCI) in rats. SP injection (1000 mg/kg) 5 min after sham injury (Sham-SP) or CCI (CCI-SP) significantly increased arterial pyruvate (p < 0.005) and lactate (p < 0.001) compared to that of saline-treated rats with CCI (CCI-Sal). Serum glucose also increased significantly in CCI-SP compared to that in CCI-Sal rats (p < 0.05), but not in Sham-SP rats. MD(pyr) was not altered after CCI-Sal, whereas MD(lac) levels within the cerebral cortex significantly increased bilaterally (p < 0.05) and those for MD(glc) decreased bilaterally (p < 0.05). MD(pyr) levels increased significantly in both Sham-SP and CCI-SP rats (p < 0.05 vs. CCI-Sal) and were higher in left/injured cortex of the CCI-SP group (p < 0.05 vs. sham-SP). In CCI-SP rats the contralateral MD(lac) decreased below CCI-Sal levels (p < 0.05) and the ipsilateral MD(glc) levels exceeded those of CCI-Sal rats (p < 0.05). Rats with a single low (500 mg/kg) or high dose (1000 mg/kg) SP treatment had fewer damaged cortical cells 6 h post-CCI than did saline-treated rats (p < 0.05), but three hourly injections of SP (1000 mg/kg) were needed to significantly reduce contusion volume 2 weeks after CCI. Thus, a single intraperitoneal SP treatment increases circulating levels of three potential brain fuels, attenuates a CCI-induced reduction in extracellular glucose while increasing extracellular levels of pyruvate, but not lactate, and can attenuate cortical cell damage occurring within 6 h of injury. Enduring (2 week) neuronal protection was achieved only with multiple SP treatments within the first 2 h post-CCI, perhaps reflecting the need for additional fuel throughout the acute period of increased metabolic demands induced by CCI.

Beneficial effects of sodium or ethyl pyruvate after traumatic brain injury in the rat

Sodium pyruvate (SP) treatment initiated within 5 min post-injury is neuroprotective in a rat model of unilateral cortical contusion injury (CCI). The current studies examined: (1) effects of delayed SP treatments (1000 mg/kg, i.p., at 1, 12 and 24h), (2) effects of single (1h) or multiple (1, 12 and 24h) ethyl pyruvate treatments (EP; at 20 or 40 mg/kg, i.p.), and (3) mechanisms of action for pyruvate effects after CCI. In Experiment 1, both SP and EP treatment(s) significantly reduced the number of dead/dying cells in the ipsilateral hippocampus (dentate hilus+CA3(c) and/or CA3(a-b) regions) at 72 h post-CCI. Pyruvate treatment(s) attenuated CCI-induced reductions of cerebral cytochrome oxidase activity at 7 2h, significantly improving activity in peri-contusional cortex after multiple SP or EP treatments. Optical density measures of ipsilateral CD11b immuno-staining were significantly increased 72 h post-CCI, but these measures of microglia activation were not different from sham injury values in SP and EP groups with three post-CCI treatments. In Experiment 2, three treatments (1, 12 and 24h) of SP (1000 mg/kg) or EP (40 mg/kg) significantly improved recovery of beam-walking and neurological scores in the first 3 weeks after CCI, and EP treatments significantly improved spatial working memory 1 week post-CCI. Ipsilateral CA3(b) neuronal loss, but not cortical tissue loss, was significantly reduced 1 month post-CCI with pyruvate treatments begun 1h post-CCI. Thus, delayed pyruvate treatments after CCI are neuroprotective and improve neurobehavioral recovery; these effects may be mediated by improved metabolism and reduced inflammation.

The biochemical basis for the anti-inflammatory and cytoprotective actions of ethyl pyruvate and related compounds

Pyruvate is an important metabolic intermediate, and also is an effective scavenger of hydrogen peroxide and other reactive oxygen species (ROS). Pharmacological administration of pyruvate has been shown to improve organ function in animal models of oxidant-mediated cellular injury. However, pyruvate is relatively unstable in aqueous solutions, which could limit the therapeutic potential of this compound. Ethyl pyruvate (EP), a simple derivative of pyruvic acid, is also an ROS scavenger, but seems to exert pharmacological effects, such as suppression of inflammation, which are at least quantitatively different and in some instances are qualitatively distinct from those exerted by pyruvate anion. Treatment with EP has been shown to improve survival and/or ameliorate organ dysfunction in a wide variety of pre-clinical models of acute illnesses, such as severe sepsis, acute pancreatitis and stroke. Using other animal models, some studies have demonstrated that more prolonged treatment with EP can ameliorate inflammatory bowel disease or slow the rate of growth of malignant tumors. In a clinical trial of patients undergoing cardiac surgery, treatment with EP was shown to be safe, but it failed to improve outcome. The true therapeutic potential of EP and related compounds remains to be elucidated. In this review, some of the biochemical mechanisms, which might be responsible for the pharmacological effects of EP, are discussed.

Liver apoptosis is age dependent and is reduced by activation of peroxisome proliferator-activated receptor-gamma in hemorrhagic shock

A clinical observation in pediatric and adult intensive care units is that the incidence of multiple organ failure in pediatric trauma victims is lower than in adult patients. However, the molecular mechanisms are not yet defined. Recent experimental studies have shown that the nuclear peroxisome proliferator-activated receptor-gamma (PPARgamma) modulates the inflammatory process. In this study, we hypothesized that severity of liver injury may be age dependent and PPARgamma activation may provide beneficial effects. Hemorrhagic shock was induced in anesthetized young (3-5 mo old) and mature male Wistar rats (11-13 mo old) by withdrawing blood to a mean arterial blood pressure of 50 mmHg. After 3 h, rats were rapidly resuscitated with shed blood. Animals were euthanized 3 h after resuscitation. In mature rats, liver injury appeared more pronounced compared with young rats and was characterized by marked hepatocyte apoptosis, extravasation of erythrocytes, and accumulation of neutrophils. The ratio between the antiapoptotic protein Bcl-2 and the proapoptotic protein BAX was lower, whereas activity of caspase-3, the executioner of apoptosis, was higher in liver of mature rats compared with young rats. Plasma alanine aminotransferase levels were not different between the two age groups. This heightened liver apoptosis was associated with a significant downregulation of PPARgamma DNA binding in mature rats compared with young rats. Treatment with the PPARgamma ligand ciglitazone significantly reduced liver apoptosis in mature rats. Our data suggest that liver injury after severe hemorrhage is age dependent and PPARgamma activation is a novel hepatoprotective mechanism.

Pyruvate prevents aging of mouse oocytes

Inhibiting oocyte aging is important not only for healthy reproduction but also for the success of assisted reproduction techniques. Although our previous studies showed that cumulus cells accelerated aging of mouse oocytes, the underlying mechanism is unknown. The objective of this paper was to study the effects of pyruvate and cumulus cells on mouse oocyte aging. Freshly ovulated mouse cumulus-oocyte complexes (COCs) or cumulus-denuded oocytes (DOs) were cultured in Chatot-Ziomek-Bavister (CZB) medium or COC-conditioned CZB medium supplemented with different concentrations of pyruvate before being examined for aging signs and developmental potential. Pyruvate supplementation to CZB medium decreased rates of ethanol-induced activation in both COCs and DOs by maintaining their maturation-promoting factor activities, but more pyruvate was needed for COCs than for DOs. Addition of pyruvate to the COC-conditioned CZB also alleviated aging of DOs. Observations on cortical granules, level of BCL2 proteins, histone acetylation, intracellular concentration of glutathione, and embryo development all confirmed that pyruvate supplementation inhibited aging of mouse oocytes. It is concluded that the aging of mouse oocytes, facilitated by culture in COCs, can be partially prevented by the addition of pyruvate to the culture medium.

Single sample extraction protocol for the quantification of NAD and NADH redox states in Saccharomyces cerevisiae

A robust redox extraction protocol for quantitative and reproducible metabolite isolation and recovery has been developed for simultaneous measurement of nicotinamide adenine dinucleotide (NAD) and its reduced form, NADH, from Saccharomyces cerevisiae. Following culture in liquid media, yeast cells were harvested by centrifugation and then lysed under nonoxidizing conditions by bead blasting in ice-cold, nitrogen-saturated 50 mM ammonium acetate. To enable protein denaturation, ice cold nitrogen-saturated CH(3)CN/50 mM ammonium acetate (3:1 v/v) was added to the cell lysates. Chloroform extractions were performed on supernatants to remove organic solvent. Samples were lyophilized and resuspended in 50 mM ammonium acetate. NAD and NADH were separated by HPLC and quantified using UV-Vis absorbance detection. NAD and NADH levels were evaluated in yeast grown under normal (2% glucose) and calorie restricted (0.5% glucose) conditions. Results demonstrate that it is possible to perform a single preparation to reliably and robustly quantitate both NAD and NADH contents in the same sample. Robustness of the protocol suggests it will be (i) applicable to quantification of these metabolites in other cell cultures; and (ii) amenable to isotope labeling strategies to determine the relative contribution of specific metabolic pathways to total NAD and NADH levels in cell cultures.

Hypertonic 15% sodium pyruvate offers no initial resuscitation advantage compared with 8% hypertonic NACl in sheep with multiple hemorrhages

Initial fluid resuscitation of hemorrhagic shock might be enhanced by the infusion of monocarboxylate-energy substrates. We evaluated hemodynamics, metabolism, and fluid dynamics for initial resuscitation of hemorrhage using small volume 15% sodium pyruvate solution (HPY) compared with osmotically matched 8% hypertonic saline (HS). Instrumented conscious sheep were hemorrhaged 25 mL/kg at time zero through 15 min (T0-T15) and 5 mL/kg for 5 min at T50 to T55 and T70 to T75. Fluid resuscitation from T30 to T180 was performed by a computer-controlled closed-loop system, which titrated infusion rate to a mean arterial pressure of 90 mmHg. Initial infusion was 4 mL/kg of either HPY or HS, followed by the administration of lactated Ringer. Both HPY and HS restored cardiac index similarly. The lactate/pyruvate ratio was used to assess metabolic debt and was significantly higher (T180), whereas oxygen delivery was significantly lower (T120) with HPY versus HS. Total fluid administered was similar, with 43.7 +/- 6.2 mL/kg for HPY and 39.4 +/- 6.8 mL/kg for HS. Plasma volume was similarly increased and approached baseline values for both groups. Initial resuscitation with small volume HPY offered no hemodynamic or metabolic advantage compared with small volume HS when the fluids were infused to an end point pressure.

Pyruvate reduces DNA damage during hypoxia and after reoxygenation in hepatocellular carcinoma cells

Pyruvate is located at a crucial crossroad of cellular metabolism between the aerobic and anaerobic pathways. Modulation of the fate of pyruvate, in one direction or another, can be important for adaptative response to hypoxia followed by reoxygenation. This could alter functioning of the antioxidant system and have protective effects against DNA damage induced by such stress. Transient hypoxia and alterations of pyruvate metabolism are observed in tumors. This could be advantageous for cancer cells in such stressful conditions. However, the effect of pyruvate in tumor cells is poorly documented during hypoxia/reoxygenation. In this study, we showed that cells had a greater need for pyruvate during hypoxia. Pyruvate decreased the number of DNA breaks, and might favor DNA repair. We demonstrated that pyruvate was a precursor for the biosynthesis of glutathione through oxidative metabolism in HepG2 cells. Therefore, glutathione decreased during hypoxia, but was restored after reoxygenation. Pyruvate had beneficial effects on glutathione depletion and DNA breaks induced after reoxygenation. Our results provide more evidence that the alpha-keto acid promotes the adaptive response to hypoxia followed by reoxygenation. Pyruvate might thus help to protect cancer cells under such stressful conditions, which might be harmful for patients with tumors.

Geldanamycin inhibits hemorrhage-induced increases in caspase-3 activity: role of inducible nitric oxide synthase

Hemorrhage has been shown to increase inducible nitric oxide synthase (iNOS) and deplete ATP levels in tissues and geldanamycin limits both processes. Moreover, it is evident that inhibition of iNOS reduces caspase-3 and increases survival. Thus we sought to identify the molecular events responsible for the beneficial effect of geldanamycin. Hemorrhage in mice significantly increased caspase-3 activity and protein while treatment with geldanamycin significantly limited these increases. Similarly, geldanamycin inhibited increases in proteins forming the apoptosome (a complex of caspase-9, cytochrome c, and Apaf-1). Modulation of the expression of iNOS by iNOS gene transfection or siRNA treatment demonstrated that the level of iNOS correlates with caspase-3 activity. Our data indicate that geldanamycin limits caspase-3 expression and protects from organ injury by suppressing iNOS expression and apoptosome formation. Geldanamycin, therefore, may prove useful as an adjuvant in fluids used to treat patients suffering blood loss.

RESUSCITATION WITH HYDROXYETHYL STARCH SOLUTION PREVENTS NUCLEAR FACTOR κB ACTIVATION AND OXIDATIVE STRESS AFTER HEMORRHAGIC SHOCK AND RESUSCITATION IN RATS

Fluid resuscitation is vital for treating traumatic hemorrhagic shock (HS), but reperfusion is believed to have the adverse consequences of generating reactive oxygen species and inflammatory cytokines, both of which cause multiple organ dysfunctions. We investigated the effects of various resuscitation fluids on the changes of redox-sensitive molecules after HS and fluid resuscitation (HS/R). We induced HS by bleeding male Sprague-Dawley rats to a blood pressure of 30 to 40 mmHg for 60 minutes. Thirty minutes later, the rats were killed (HS group) or immediately resuscitated with shed blood (HS + BL group), L-isomer lactated Ringer's solution (HS + LR group), or hydroxyethyl starch (HS + HES group). After HS, we found a significant increase in nuclear factor kappaB DNA binding activity, which was effectively inhibited using HES solution or blood resuscitation. Moreover, resuscitation with blood or LR solution, but not HES solution, induced significant oxidative stress, manifested by a high ratio of oxidized glutathione to reduced glutathione in the lungs, liver, and spleen. HS alone, however, did not increase the ratio of the oxidized glutathione to reduced glutathione in all organs. Although the protein expression of anti-apoptotic Bcl-2 and pro-apoptotic Bax varied in different organs, we found that resuscitation using HES solution prevented the HS-induced reduction of the Bcl-2/Bax ratio in the heart. HES solution was an appropriate resuscitation fluid in reversing nuclear factor kappaB activation, maintaining the Bcl-2/Bax ratio, and preventing oxidative stress after acute HS.

Ethyl pyruvate: a novel anti-inflammatory agent

Ethyl pyruvate (EP) is a simple derivative of the endogenous metabolite, pyruvic acid. Treatment with EP has been shown to improve survival and/or ameliorate organ dysfunction in a wide variety of preclinical models of critical illnesses, such as severe sepsis, acute respiratory distress syndrome, acute pancreatitis and stroke. EP was originally regarded as simply a way to administer pyruvate anion, whilst avoiding some of the problems associated with the instability of pyruvate in aqueous solutions. Increasingly, however, it is becoming apparent that certain pyruvate esters, including EP, have pharmacological effects, such as suppression of inflammation, that are quite distinct from those exerted by pyruvate anion. EP has been tested in human volunteers and shown to be safe at clinically relevant doses. It remains to be determined whether EP can be used successfully to treat human diseases.

HYPOTENSIVE HEMORRHAGE INCREASES CALCIUM UPTAKE CAPACITY AND BCL-XL CONTENT OF LIVER MITOCHONDRIA

We tested the hypothesis that the response of mitochondrial uptake of calcium and content of Bcl proteins to reversible hemorrhagic shock increases the vulnerability for hepatocellular death. Pentobarbital-anesthetized rats were bled to a mean arterial pressure of 30 to 40 mmHg for 1 h. A subset was then resuscitated (isotonic sodium chloride solution, three times shed volume). Liver mitochondria were isolated at the end of hemorrhage and 1.5 h after the onset of resuscitation. Resuscitation accelerated mitochondrial respiration in the presence of adenosine diphosphate (state 3) above control (P<0.01). The respiratory control ratio ([RCR] state 3/state 4) was calculated using the respiratory rate in the presence of carboxyatractyloside (state 4). The RCR was depressed at the end of hemorrhage and recovered completely in response to resuscitation (P<0.05). The mitochondrial capacity for calcium uptake increased at the end of hemorrhage and remained greater than control (P<0.01) after resuscitation when plasma ornithine carbamoyltransferase (an index of hepatocellular injury) was greater than control (P<0.05). At this time, the capacity for calcium uptake was correlated with plasma ornithine carbamoyltransferase (r=0.819, P<0.01). Mitochondrial content of Bcl-xL, an antiapoptotic protein, was increased at the end of hemorrhage (P<0.03) with no further change after resuscitation and no change in mitochondrial Bak, a proapoptotic protein. Thus, mitochondrial mechanisms are triggered early during reversible hypovolemia that may limit the intensity of intracellular calcium signaling and its potential to cause cellular injury and death.

Small volume resuscitation with tempol is detrimental during uncontrolled hemorrhagic shock in rats

BACKGROUND

In a previous study, titration of a hypertonic saline (HTS) solution during severe uncontrolled hemorrhagic shock (UHS) failed to reduce mortality. In a separate study, a novel antioxidant, polynitroxylated albumin (PNA) plus tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl), infused during shock increased long-term survival. We hypothesized that combining potent antioxidants with a hypertonic solution during UHS would preserve the logistical advantage of small volume resuscitation and improve survival.

METHODS

An UHS outcome model in rats was used. UHS phase I (90 min) included blood withdrawal of 30 ml/kg over 15 min, followed by tail amputation for uncontrolled bleeding. At 20 min, rats were randomized to four groups (n=10 each) for hypotensive resuscitation from 20 to 90 min (mean arterial pressure [MAP] > or = 40 mmHg): HTS/starch group received 7.2% NaCl/10% hydroxyethyl starch; HTS/albumin group received 7.5% NaCl/20% albumin; HTS/PNA group received 7.5% NaCl/20% PNA; HTS/albumin+tempol group received 7.5% NaCl/20% albumin plus tempol. Resuscitation phase II (180 min) included hemostasis, return of shed blood and administration of fluids to restore MAP > or = 80 mmHg. Observation phase III was to 72 h.

RESULTS

The total amount of fluid required to maintain hypotensive MAP during HS was low and did not differ between groups (range: 3.4+/-1.9 to 5.3+/-2.5 ml/kg). The rate of fluid administration required was higher in the HTS/albumin+tempol group compared to all other groups (p=0.006). Additional uncontrolled blood loss was highest in the HTS/PNA group (16.2+/-5.7 ml/kg [p=0.01] versus 10.4+/-7.9 ml/kg in the HTS/starch group, 7.7+/-5.2 ml/kg in the HTS/albumin group and 8.2+/-7.1 ml/kg in the HTS/albumin+tempol group). MAP after start of resuscitation in phase I was lower in the HTS/albumin+tempol group than the HTS/albumin or HTS/PNA groups (p<0.01). This group was also less tachycardic. Long-term survival was low in all groups (2 of 10 after HTS/starch and 1 of 10 after HTS/albumin, 3 of 10 after HTS/PNA, 1 of 10 after HTS/albumin+tempol). Median survival time was shortest in the HTS/albumin+tempol group (72 min [CI 34-190]) compared to all other groups (p=0.01).

CONCLUSIONS

Despite its benefits in other model systems, free tempol is potentially hazardous when combined with hypertonic fluids. PNA abrogates these deleterious effects on acute mortality but may lead to increased blood loss in the setting of UHS.

Androstenediol inhibits the trauma-hemorrhage-induced increase in caspase-3 by downregulating the inducible nitric oxide synthase pathway

Soft tissue trauma and hemorrhage (T-H) diminishes various aspects of liver function, while it increases hepatic nitrate/nitrite, inducible nitric oxide synthase (iNOS), and endothelin-1 levels. Treatment with androstenediol (AED) inhibits the T-H-induced alterations of the above parameters. We sought to identify the molecular events underlying the beneficial effect of AED. Exposure of rats to T-H significantly increased the caspase-3 activity and protein, whereas treatment with AED significantly limited these increases. AED treatment also suppressed the T-H-induced increase in iNOS by effectively altering the levels of key transcription factors involved in the regulation of iNOS expression. Immunoprecipitation and immunoblotting analyses indicate that T-H increased apoptosome formation, and AED treatment significantly decreased it. Modulating the iNOS protein by transfecting cells with iNOS gene or small interfering RNA further confirmed the correlation between iNOS and caspase-3. Our data indicate that AED limits caspase-3 expression by suppressing the expression of transcription factors involved in the production of iNOS, resulting in decreased apoptosome. AED can potentially be a useful adjuvant for limiting liver apoptosis following T-H shock.