Injury to primary cultures of rat heart endothelial cells by hypoxia and glucose deprivation

Summary Primary cultures of rat heart endothelial cells were subjected to simulated conditions of ischemia: hypoxia and glucose deprivation for 4 and 24 hr. Cellular injury was evaluated by measuring changes in viability, total protein, cellular morphology, and leakage of cytoplasmic enzymes from the cells into the culture medium. Deprivation of oxygen and glucose for 4 or 24 hr did not lethally injure the cells as noted by no change in cell viability, morphology, and total protein when compared to controls. However, reversible or nonlethal cellular injury was produced as reflected by a significant release of lactate dehydro-genase (LDH) from the cells into the medium after treatment with hypoxia and glucose deprivation for 4 or 24 hr. When the cultures were deprived of glucose, but were oxygenated, cellular injury was not evident after 24 hr. Deprivation of oxygen but not glucose resulted in significant loss of LDH after 4 or 24 hr. When the cultures were allowed to recover after oxygen and glucose deprivation in complete medium containing 1000 mg glucose per l and a normal atmosphere of 20% O₂, they had levels of LDH leakage comparable to those of control cultures. This study was supported by Research Grant HL 18647 from the National Heart, Lung, and Blood Institute and by a National Chicano Council on Higher Education Post-Doctoral Fellowship awarded to D. Acosta from the Ford Foundation. Additional support was provided to D. Acosta by a Faculty Research Assignment Award from the University of Texas Research Institute.     

Ischemic myocardial injury in cultured heart cells: Leakage of cytoplasmic enzymes from injured cells

Summary An in vitro model of myocardial ischemia has been established with primary monolayer cultures of postnatal rat myocardial cells. Ischemic conditions were simulated in vitro by subjecting the myocardial cell cultures to various levels of oxygen and glucose deprivation. The experimental protocol consisted of treatment with 20% or 0% O₂ and 1000, 500 or 0 mg glucose per 1 of medium for 4 or 24 hr. Control cultures were treated with 20% O₂ and 1000 mg glucose. After the ischemic treatments, cultures of beating muscle (M) cells were evaluated for signs of injury, i.e. leakage of cytoplasmic enzymes into the culture medium. Differences were found in leakage of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) from the cultures that were exposed to partial ischemia of glucose deprivation and from those cultures that were exposed to total ischemia of oxygen and glucose deprivation. Glucose deprivation alone resulted in a slight-to-moderate loss of LDH and CPK from the cells, whereas total ischemia resulted in a significant release of the two cytoplasmic enzymes. When the cultures were allowed to recover after ischemic treatment in complete medium (1000 mg glucose) and a normal atmosphere of 20% O₂, they had levels of LDH leakage comparable to those of control cultures. Cell viability and total protein content of the ischemic cultures did not differ significantly from controls. This study was supported by Research Grant HL 18647 from the National Heart, Lung, and Blood Institute.     

Injury to primary cultures of rat heart endothelial cells by hypoxia and glucose deprivation

Primary cultures of rat heart endothelial cells were subjected to simulated conditions of ischemia: hyposia and glucose deprivation for 4 and 24 hr. Cellular injury was evaluated by measuring changes in viability, total protein, cellular morphology, and leakage of cytoplasmic enzymes from the cells into the culture medium. Deprivation of oxygen and glucose for 4 or 24 hr did not lethally injure the cells as noted by no change in cell viability, morphology, and total protein when compared to controls. However, reversible or non-lethal cellular injury was produced as reflected by a significant release of lactate dehydrogenase (LDH) from the cells into the medium after treatment with hypoxia and glucose deprivation for 4 or 24 hr. When the cultures were deprived of glucose, but were oxygenated, cellular injury was not evident after 24 hr. Deprivation of oxygen but not glucose resulted in significant loss of LDH after 4 or 24 hr. When the cultures were allowed to recover after oxygen and glucose deprivation in complete medium containing 1000 mg glucose per 1 and a normal atmosphere of 20% O2, they had levels of LDH leakage comparable to those of control cultures.     

Indices of partial oxygen deprivation in the culture medium of cardiac cells

Three indexes of partial oxygen deprivation, i.e. hypoxanthine, alpha HBDH and CK, were investigated in rat heart cell cultures, 7 day-old. Enzyme release in the medium and hypoxanthine uptake by the cells pointed out both oxygen and glucose deprivation, which modelized ischemia. Conversely, hypoxanthine release pointed out oxygen deprivation, in the presence of glucose however, which modelized hypoxia, whereas there was no enzyme leakage in the latter condition.     

Citrate,Beneficial or Deleterious in the CNS?

Cerebellar granule neurons were incubated with or without glucose (3 mM) in the presence or absence of citrate (20 mM) using normoxic and/or hypoxic incubation conditions. During 4 h of hypoglycemia and also during hypoxia plus hypoglycemia, citrate increased lactate dehydrogenase (LDH) leakage from the cells and decreased mitochondrial activity, the latter was also the case in the presence of glucose. After 24 h of hypoglycemia, however, citrate decreased LDH leakage slightly, possibly due to its metabolism in the tricarboxylic acid cycle under these conditions. It should be noted that during mild hypoxia plus hypoglycemia a reduced LDH leakage was observed when compared to hypoglycemia alone. The 4 h low oxygen period did protect the neurons also during the 20 h re-oxygenation period. The present study might indicate that incubation of brain cell cultures in an atmosphere of air (30% oxygen) and 5% CO₂, which is used in most laboratories, can be toxic and that oxygen concentration should be lowered considerably to mimic conditions in the brain.     

Effects of hypoxia and reoxygenation on adult rat heart cell metabolism

Isolated adult rat heart cells were used to study the effects of oxygen deprivation followed by reoxygenation upon myocardial metabolism. Calcium-tolerant nonbeating myocytes were incubated for 5, 30, or 60 min under 100% oxygen or 100% nitrogen and then rinsed with oxygenated buffer. Substrate oxidation was studied by incubating the cells with 14C-labeled glucose, pyruvate, or octanoate and determining the rates of 14CO2 production from the individual substrates. After 5 min of hypoxia, metabolism of glucose, as assessed by glucose oxidation and lactate production, was significantly depressed. Pyruvate and octanoate oxidation were unaltered. Oxygen consumption was also unchanged by short-term hypoxia and reoxygenation. With reoxygenation after 30 min of oxygen deprivation, more exaggerated changes in glucose metabolism were noted as well as a depression in pyruvate oxidation and unaltered octanoate oxidation. Oxidation of octanoate was slightly depressed after 60 min of hypoxia. Cell viability assessed after reoxygenation was not significantly altered until 60 min of oxygen deprivation. The results indicate that cytosolic changes occur after short periods of hypoxia followed by reoxygenation, whereas mitochondrial function is more resistant to damage inflicted by hypoxia and reoxygenation.     

Hypoxia induced metabolism dysfunction of rat astrocytes in primary cell cultures

In order to study the astroglial contribution to hypoxic injury on brain tissue metabolism, modifications of glutamine synthetase (GS) lactate dehydrogenase (LDH) enolase and malate dehydrogenase activity produced by reduced oxygen supply have been determined in primary cultures of astrocytes prepared from newborn rat cerebral cortex. Enzymatic activities were measured immediately after the hypoxic treatment (9 h) and during post injury recovery. GS level is significantly decreased in response to low oxygen pressure and increased above control value during the post hypoxic recovery period. The magnitude of GS reduction by hypoxia depends on the age of the cells in culture. Lactate dehydrogenase and enolase levels were significantly enhanced during the two periods considered. No modification of the MDH level was observed. The synthesis of LDH isoenzymes containing mainly M subunits is specifically induced by hypoxia. Our results suggest that astroglial cells may represent a particularly sensitive target toward hypoxia injury in brain tissue. Low oxygen pressure available may modify some fundamental metabolical functions of these cells such as glutamate turnover and lactic acid accumulation.     

Exercise-induced peptide EIP-22 protect myocardial from ischaemia/reperfusion injury via activating JAK2/STAT3 signalling pathway

Recent studies have revealed that exercise has myocardial protective effects, but the exact mechanism remains unclear. Studies have increasingly found that peptides play a protective role in myocardial ischaemia-reperfusion (I/R) injury. However, little is known about the role of exercise-induced peptides in myocardial I/R injury. To elucidate the effect of exercise-induced peptide EIP-22 in myocardial I/R injury, we first determined the effect of EIP-22 on hypoxia/reperfusion (H/R)- or H₂O₂-induced injury via assessing cell viability and lactate dehydrogenase (LDH) level. In addition, reactive oxygen species (ROS) accumulation and mitochondrial membrane potential (MMP) was assessed by fluorescence microscope. Meanwhile, Western blot and TUNEL methods were used to detect apoptosis level. Then, we conducted mice I/R injury model and verified the effect of EIP-22 by measuring cardiac function, evaluating heart pathology and detecting serum LDH, CK-MB and cTnI level. Finally, the main signalling pathway was analysed by RNA-seq. In vitro, EIP-22 treatment significantly improved cells viabilities and MMP and attenuated the LDH, ROS and apoptosis level. In vivo, EIP-22 distinctly improved cardiac function, ameliorated myocardial infarction area and fibrosis and decreased serum LDH, CK-MB and cTnI level. Mechanistically, JAK/STAT signalling pathway was focussed by RNA-seq and we confirmed that EIP-22 up-regulated the expression of p-JAK2 and p-STAT3. Moreover, AG490, a selective inhibitor of JAK2/STAT3, eliminated the protective roles of EIP-22. The results uncovered that exercise-induced peptide EIP-22 protected cardiomyocytes from myocardial I/R injury via activating JAK2/STAT3 signalling pathway and might be a new candidate molecule for the treatment of myocardial I/R injury.     

grp75对细胞缺糖损伤的保护作用

为研究ｇｒｐ７５的功能,对过表达ｇｒｐ７５的ＣＨＬ细胞进行了无糖培养以施加能量代谢应激,运用台盼蓝染色计数、ＬＤＨ释放测定和流式细胞术等方法评估其损伤程序。结果显示,无糖培养５ｈ,过表达ｇｒｐ７５细胞和对照组细胞比较,细胞活率、亚二倍体细胞率均无明显差别;无糖培养１０ｈ,过表达ｇｒｐ７５细胞的活率高于对照组（Ｐ〈０．０１）,亚二倍体细胞率低于对照组（Ｐ〈０．０５）;无糖培养至２０ｈ,两组细胞活率和     

Oxygen and substrate deprivation on isolated rat cardiac myocytes: temporal relationship between electromechanical and biochemical consequences

The effects of hypoxia and reoxygenation on action potentials (AP), contractions, and certain biochemical parameters were studied in isolated rat ventricular myocytes in monolayer culture in the presence and absence of glucose. Substrate deprivation alone had no influence on the basal properties. In the presence of glucose, a 4-h hypoxic treatment caused only a moderate decrease in AP amplitude and rate. In substrate-free conditions, hypoxia induced a gradual decline in plateau potential level and in AP duration and rate, followed by rhythm abnormalities and a failure of the electromechanical coupling. Spontaneous AP generation then ceased, and the resting potential decreased with increased duration of hypoxia. These alterations were associated with a decrease in ATP content, an increase in the lactate production, and a leakage of about 50% of the total cellular lactate dehydrogenase (LDH). Cells reoxygenated after 150 min hypoxia recovered near-normal function, while the ATP depletion ceased and the rate of lactate and LDH loss was diminished. Conversely, cells reoxygenated after 4 h hypoxia exhibited a further decrease of the residual resting polarization and no change in the decline of intracellular ATP and in the efflux of cytosolic lactate and LDH. The results of this study indicate that (1) the sequence and the extent of functional alterations are dependent on the duration of hypoxia in the absence of exogenous substrate and (2) ATP depletion and the amount of lactate and LDH released during hypoxia are related to the shift from reversibly to irreversibly damaged cells.     

Reanimation of cultured mammalian myocardial cells during multiple cycles of trypsinization-freezing-thawing

Summary Isolated newborn rat heart cells were cultured for several days, then subjected to a standard procedure of trypsinization, slow freezing in 10% dimethylsulfoxide, storage at −180° to −190°C for 1 to 3 days, rapid thawing, and recultivation. The same cells were recycled two more times in identical procedures. Morphological observations were made by phase-contrast optics and cinematography between each cycle and at the end of every experiment. After comparing the cellular morphology and contractile patterns of treated cells with control cultures, it was shown from the results of more than 15 experiments that most myocardial cells survived the standard procedures of trypsinization, freezing, and thawing and regained the ability to contract normally and form synchronized networks. Evidence was obtained which indicates that a cycle of the standard trypsinization-freezing-thawing procedure permits a recovery rate of 83 to 91% viable cells, with myocardial cells surviving to the same extent as endothelial cells. Of the cells which were nonviable, approximately half the deaths were a result of prior damage by trypsin and half were due to the freezing-thawing procedures. The same proportion of spontaneously contracting myocardial cells was observed after a cycle of trypsinization-freezing-thawing as before. Occasionally, there was a delay of 24 hr after thawing before myocardial cells began contracting spontaneously in vitro. An experiment using Viokase (in place of trypsin) and glycerol (in place of dimethylsulfoxide) excellent results after one cycle of freezing-thawing. It was concluded that myocardial cells exhibited a remarkable recovery from the toxic effects of trypsin and the traumatic influences of multiple freezing-thawing procedures. Endothelial cells in the cultures survived the same procedures and proliferated normally in vitro. Supported by United States Public Health Service Grants NS-09524 from the National Institute of Neurological Diseases and Stroke, CA-12067 from the National Cancer Institute, HL-15103 (Specialized Center of Research) from the National Heart and Lung Institute, and United States Public Health Service Training Grant 5-TO1-DE-0024 from the National Institute of Dental Research. A preliminary report of this paper was presented at the 24th Annual Meeting of the Tissue Culture Association, Boston, June 4–7, 1973, and appears as an abstract: Kasten, F. H. and D. Yip. 1973. Reanimation of cultured mammalian myocardial cells during multiple cycles of freeze-thawing. In Vitro 8: 409.     

Ischemic myocardial injury in cultured heart cells: preliminary observations on morphology and beating activity

An in vitro model of myocardial ischemia has been established with primary monolayer cultures of neonatal rat heart cells. Ischemic conditions were simulated in vitro by subjecting the heart cell cultures to various levels of oxygen and glucose deprivation. After the ischemic treatments, cultures of beating muscle (M) cells were evaluated for functional and morphological changes. The experimental protocol consisted of treatment with 20% or 0% O2 and 1000, 500 or 0 mg glucose per 1 of medium for 4, 12 or 24 hr. Control cultures were treated with 20% O2 and 1000 mg glucose. The morphological alterations induced by the deficiency of O2 and glucose in the medium were the formation of pseudopodia and cytoplasmic vacuoles; increased cytoplasmic granulation; and the formation of abnormal cell shapes, such as long, spindly shaped M cells. There was a time-dependent decrease in beating activity as the M cells were exposed to longer durations of ischemic conditions. However, if the cultures were replenished with complete medium (1000 mg glucose) and 20% O2, the cells regained their ability to beat.     

热休克蛋白90在缺氧心肌细胞中表达的初步研究

观察热休克蛋白90(HSP90)在缺氧心肌细胞中的表达变化规律,并初步阐明HSP90在早期心肌缺氧损害中的作用。方法:原代培养SD大鼠乳鼠心肌细胞,随机分为正常对照组、缺氧组和加HSP90阻断剂格尔霉素(geldanamycin,GA)预处理后再缺氧组(GA 缺氧组),蛋白免疫印迹法(western blot)及间接免疫荧光法检测缺氧1、3、6、12、24h后心肌细胞中HSP90蛋白分布表达情况,并检测细胞上清中肌酸激酶同工酶(CK-MB)及乳酸脱氢酶(LDH)的含量变化。结果:心肌细胞缺氧3h后HSP90蛋白在胞浆内表达量升高,持续到12h达到峰值。与单纯缺氧组相比,GA 缺氧组中LDH,CK-MB含量在不同时相点均有显著升高。结论:缺氧早期即可引起心肌细胞胞浆中HSP90蛋白表达增强,HSP90可能在早期心肌缺氧损害中发挥其内源性抗损伤机制。     

Arctic ground squirrel neuronal progenitor cells resist oxygen and glucose deprivation-induced death

AIM: To investigate the influence of ischemia/reperfusion on arctic ground squirrel(AGS) neuronal progenitor cells(NPCs), we subjected these cultured cells to oxygen and glucose deprivation.METHODS: AGS NPCs were expanded and differentiated into NPCs and as an ischemia vulnerable control, commercially available human NPCs(hNPCs) were seeded from thawed NPCs. NPCs, identified by expression of TUJ1 were seen at 14-21 d in vitro(DIV). Cultures were exposed to control conditions, hypoxia, oxygen and glucose deprivation or glucose deprivation alone or following return to normal conditions to model reperfusion. Cell viability and death were assessed from loss of ATP as well as from measures of alamarB lue~ and lactate dehydrogenase in the media and from counts of TUJ1 positive cells using immunocytochemistry. Dividing cells were identified by expression of Ki67 and phenotyped by double labeling with GFAP, MAP2 ab or TUJ1. RESULTS: We report that when cultured in NeuraLife~(TM), AGS cells remain viable out to 21 DIV, continue to express TUJ1 and begin to express MAP2 ab. Viability of hN PCs assessed by fluorescence alamarB lue(arbitrary units) depends on both glucose and oxygen availability [viability of hNPCs after 24 h oxygen glucose deprivation(OGD) with return of oxygen and glucose decreased from 48151 ± 4551 in control cultures to 43481 ± 2413 after OGD, P 0.05]. By contrast, when AGS NPCs are exposed to the same OGD with reperfusion at 14 DIV, cell viability assessed by alamar Blue increased from 165305 ± 11719 in control cultures to 196054 ± 13977 after OGD. Likewise AGS NPCs recovered ATP(92766 ± 6089 in control and 92907 ± 4290 after modeled reperfusion; arbitrary luminescence units), and doubled in the ratio of TUJ1 expressing neurons to total dividing cells(0.11 ± 0.04 in control cultures vs 0.22 ± 0.2 after modeled reperfusion, P 0.05). Maintaining AGS NPCs for a longer time in culture lowered resistance to injury, however, did not impair proliferation of NPCs relative to other cell lineages after oxygen deprivation followed by re-oxygenation.CONCLUSION: Ischemic-like insults decrease viability and increase cell death in cultures of human NPCs. Similar conditions have less affect on cell death and promote proliferation in AGS NPCs.     

Mitochondrial BKCa channels contribute to protection of cardiomyocytes isolated from chronically hypoxic rats

Chronic hypoxia protects the heart against injury caused by acute oxygen deprivation, but its salutary mechanism is poorly understood. The aim was to find out whether cardiomyocytes isolated from chronically hypoxic hearts retain the improved resistance to injury and whether the mitochondrial large-conductance Ca2+-activated K+ (BKCa) channels contribute to the protective effect. Adult male rats were adapted to continuous normobaric hypoxia (inspired O2 fraction 0.10) for 3 wk or kept at room air (normoxic controls). Myocytes, isolated separately from the left ventricle (LVM), septum (SEPM), and right ventricle, were exposed to 25-min metabolic inhibition with sodium cyanide, followed by 30-min reenergization (MI/R). Some LVM were treated with either 30 μM NS-1619 (BKCa opener), or 2 μM paxilline (BKCa blocker), starting 25 min before metabolic inhibition. Cell injury was detected by Trypan blue exclusion and lactate dehydrogenase (LDH) release. Chronic hypoxia doubled the number of rod-shaped LVM and SEPM surviving the MI/R insult and reduced LDH release. While NS-1619 protected cells from normoxic rats, it had no additive salutary effect in the hypoxic group. Paxilline attenuated the improved resistance of cells from hypoxic animals without affecting normoxic controls; it also abolished the protective effect of NS-1619 on LDH release in the normoxic group. While chronic hypoxia did not affect protein abundance of the BKCa channel regulatory β1-subunit, it markedly decreased its glycosylation level. It is concluded that ventricular myocytes isolated from chronically hypoxic rats retain the improved resistance against injury caused by MI/R. Activation of the mitochondrial BKCa channel likely contributes to this protective effect.     

Green tea protection of hypoxia/reoxygenation injury in cultured cardiac cells

Antioxidant-rich diets exert a protective effect in diseases involving oxidative damage. Among dietary components, green tea is an excellent source of antioxidants. In this study, cultured neonatal rat cardiomyocytes were used to clarify the protective effect of a green tea extract on cell damage and lipid peroxidation induced by different periods of hypoxia followed by reoxigenation. Cultures of neonatal rat cardiomyocytes were exposed to 2--8 hr hypoxia, eventually followed by reoxygenation, in the absence or presence of alpha-tocopherol or green tea. LDH release and the production of conjugated diene lipids were measured, and appeared linearly related to the duration of hypoxia. During hypoxia, both LDH release and conjugated diene production were reduced by alpha-tocopherol and, in a dose dependent manner, by green tea, the 50 &mgr;g/ml being the most effective dose. Reoxygenation caused no further increase in LDH leakage, while it caused a significant increase in conjugate dienes, which absolute value was lower in antioxidant supplemented cells. Anyway, the ratio between conjugated diene production after hypoxia and after reoxygenation was similar in all groups, indicating that the severity of free radical-induced reoxygenation injury is proportional to the severity of previous hypoxic injury. Since hypoxic damage is reduced by alpha-tocopherol and green tea, our data suggest that any nutritional intervention to attenuate reoxygenation injury must be directed toward the attenuation of the hypoxic injury. Therefore, recommendations about a high dietary intake of antioxidants may be useful not only in the prevention, but also in the reduction of cardiac injury following ischemia.     

Effect of hypoxia on a primary cardiomyocyte culture

The primary cultures of 3-day old rats heart myocytes were used for studying hypoxia. The cells were gassed for 1 or 2 hours with 100% N2 or with the mixture of 90% N2, 5% CO2, 5% O2. The cells' morphology was tested by the light microscopy. The contractility of the cells was lost after oxygen deprivation. But it was reversible when the cells were exposed to 5% O2 for an hour and then were returned to the normal conditions. Oxygen deprivation changed the cell's morphology so that vacuolization, bubbling, contracture, exfoliation of the cell membrane from the glass surface could be observed. The number of the cells with morphological alterations increased when the content of oxygen in the gas mixture was lowered and the time of gassing was prolonged. The authors assume that the primary culture of the myocardial cells is a suitable model for studying the metabolic patterns of reversible injuries caused by one hour hypoxia (5% O2).     

Hypoxic preconditioning protects microvascular endothelial cells against hypoxia/reoxygenation injury by attenuating endoplasmic reticulum stress

Endothelial cells (ECs) are directly exposed to hypoxia and contribute to injury during myocardial ischemia/reperfusion. Hypoxic preconditioning (HPC) protects ECs against hypoxia injury. This study aimed to explore whether HPC attenuates hypoxia/reoxygenation (H/R) injury by suppressing excessive endoplasmic reticulum stress (ERS) in cultured microvascular ECs (MVECs) from rat heart. MVECs injury was measured by lactate dehydrogenase (LDH) leakage, cytoskeleton destruction, and apoptosis. Expression of glucose regulating protein 78 (GRP78) and C/EBP homologous protein (CHOP), activation of caspase-12 (pro-apoptosis factors) and phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) were detected by western blot analysis. HPC attenuated H/R-induced LDH leakage, cytoskeleton destruction, and cell apoptosis, as shown by flow cytometry, Bax/Bcl-2 ratio, caspase-3 activation and terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling. HPC suppressed H/R-induced ERS, as shown by a decrease in expression of GRP78 and CHOP, and caspase-12 activation. HPC enhanced p38 MAPK phosphorylation but decreased that of protein kinase R-like ER kinase (PERK, upstream regulator of CHOP). SB202190 (an inhibitor of p38 MAPK) abolished HPC-induced cytoprotection, downregulation of GRP78 and CHOP, and activation of caspase-12, as well as PERK phosphorylation. HPC may protect MVECs against H/R injury by suppressing CHOP-dependent apoptosis through p38 MAPK mediated downregulation of PERK activation.     

Oxygen and glucose deprivation induces mitochondrial dysfunction and oxidative stress in neurones but not in astrocytes in primary culture

In order to investigate the potential neuroprotective role played by glucose metabolism during brain oxygen deprivation, the susceptibility of cultured neurones and astrocytes to 1 h of oxygen deprivation (hypoxia) or oxygen and glucose deprivation (OGD) was examined. OGD, but not hypoxia, promotes dihydrorhodamine 123 and glutathione oxidation in neurones but not in astrocytes reflecting free radical generation in the former cells. A specific loss of mitochondrial complex-I activity, mitochondrial membrane potential collapse, ATP depletion and necrosis occurred in the OGD neurones, but not in the OGD astrocytes. Furthermore, superoxide anion but not nitric oxide formation was responsible for these effects. OGD decreased neuronal but not astrocytic NADPH concentrations; this was not observed in hypoxia and was independent of superoxide or nitric oxide formation. These results suggest that glucose metabolism would supply NADPH, through the pentose-phosphate pathway, aimed at preventing oxidative stress, mitochondrial damage and neurotoxicity during oxygen deprivation to neural cells.     

Lactate and glucose as energy substrates during, and after, oxygen deprivation in rat hippocampal acute and cultured slices

The effects of raised brain lactate levels on neuronal survival following hypoxia or ischemia is still a source of controversy among basic and clinical scientists. We have sought to address this controversy by studying the effects of glucose and lactate on neuronal survival in acute and cultured hippocampal slices. Following a 1-h hypoxic episode, neuronal survival in cultured hippocampal slices was significantly higher if glucose was present in the medium compared with lactate. However, when the energy substrate during the hypoxic period was glucose and then switched to lactate during the normoxic recovery period, the level of cell damage in the CA1 region of organotypic cultures was significantly improved from 64.3 +/- 2.1 to 74.6 +/- 2.1% compared with cultures receiving glucose during and after hypoxia. Extracellular field potentials recorded from the CA1 region of acute slices were abolished during oxygen deprivation for 20 min, but recovered almost fully to baseline levels with either glucose (82.6 +/- 10.0%) or lactate present in the reperfusion medium (108.1 +/- 8.3%). These results suggest that lactate alone cannot support neuronal survival during oxygen deprivation, but a combination of glucose followed by lactate provides for better neuroprotection than either substrate alone.