Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Multiple organ failure (MOF) is known to follow systemic inflammatory mediator activation associated with intestinal ischemia-reperfusion injury. In particular, the pulmonary microvasculature appears to be susceptible to MOF-related injury. This study was designed to evaluate the hypothesis that non-cellular plasma factors associated with intestinal ischemia without reperfusion also mediate pulmonary endothelial cell injury. Male Sprague-Dawley rats had intestinal ischemia induced by microvascular clip occlusion of the superior mesenteric artery for 30, 60, 90, or 120 min. Following each period of ischemia, plasma samples were obtained from the protal vein. Time-matched sham-operated animals served as controls. Monolayers of cultured rat pulmonary artery endothelial cells were then incubated with the plasma samples and ATP levels determined using a luciferin-luciferase assay. A 51Cr-release assay using labeled endothelial cells was performed under identical conditions to assess cytotoxicity. Endothelial cell ATP levels were 1.99 +/- 0.23 x 10(-11) mole/micrograms DNA in sham preparations. After a 4-hr incubation in plasma from the 90 and 120 min ischemia groups, cellular ATP levels fell significantly to 1.07 +/- 0.23 x 10(-11) mole/micrograms DNA, respectively (P less than 0.005). No significant cytotoxic injury resulted from incubation with plasma from the 120 min group (1.0 +/- 0.4% versus 0.8 +/- 0.4% in sham group, P = NS). All animals survived 24 hr in the sham, 30, and 60 min groups. However, survival was 40 and 0% in the 90 and 120 min groups, respectively (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pulmonary endothelial cell ATP depletion following intestinal ischemia. 152 42

The quantification of adenine nucleotides released from the heart is hampered by their rapid dephosphorylation to adenosine in the extracellular space catalyzed by highly active ectonucleotidases. To determine the total release of adenine nucleotides from isolated Langendorff-perfused guinea pig hearts, ecto 5'-nucleotidase was effectively blocked by infusion of alpha, beta-methylene-ADP (AOPCP, 50 microM). Adenine nucleotides were measured in the coronary venous effluent by the luciferin-luciferase method after enzymatic rephosphorylation to ATP. In hearts perfused at a constant flow rate (10 ml/min) with normoxic buffer (95% O2, 5% CO2) the release +/- SEM of adenine nucleotides and adenosine was 0.06 +/- 0.01 (n = 11) and 0.04 +/- 0.01 (n = 13) nmol/min. In the presence of AOPCP, the release of adenine nucleotides increased to 0.43 +/- 0.04 nmol/min (n = 9; p less than 0.05), whereas adenosine remained unchanged. Hypoxic perfusion (10% O2, 85% N2, 5% CO2) caused a threefold increase in adenine nucleotide release but a 40-fold increase in adenosine. In contrast, global ischemia (30 seconds) caused adenine nucleotide and adenosine release to rise to similar values of 1.06 +/- 0.10 and 0.80 +/- 0.14 nmol/min (n = 9). Stimulation of hearts with isoproterenol (4 nM) likewise increased the release of adenine nucleotides (0.50 +/- 0.04 nmol/min) and adenosine (0.87 +/- 0.21 nmol/min) (n = 6). To determine the cellular source of adenine nucleotides released from the heart, the coronary endothelial adenine nucleotide pool was selectively prelabeled by [3H]adenosine. Global ischemia increased the specific radioactivity of released adenine nucleotides by 57%. The findings indicate that 1) adenine nucleotides and adenosine are released at the same order of magnitude from the well-oxygenated heart; 2) beta-adrenergic stimulation and ischemia stimulate the release of adenine nucleotides and adenosine, both purines reaching vasoactive concentrations in the effluent perfusate; 3) during hypoxic perfusion only the release of adenosine is greatly enhanced; and 4) the coronary endothelium preferentially contributes to the ischemia-induced adenine nucleotide release.
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PMID:Adenine nucleotide release from isolated perfused guinea pig hearts and extracellular formation of adenosine. 174 67

Toxic oxygen species have been implicated as important mediators of injury after reperfusion of an ischemic organ. The aim of this study was to determine if prior metabolic inhibition, such as that which occurs during ischemia, potentiates oxidant injury in vitro. Bovine pulmonary artery endothelial cells were metabolically inhibited for various periods of time with or without the mitochondrial inhibitor oligomycin (650 nM). The cells were rescued from metabolic inhibition by a wash step and subsequent addition of 5.5 mM glucose. At the same time that metabolic inhibition was relieved the cells were subjected to doses of H2O2 ranging from 0 to 100 microM. ATP levels were monitored over a 2-hr time course after rescue from metabolic inhibition by the luciferin-luciferase assay. Cell viability at 2 hr after relief of metabolic inhibition was assessed by trypan blue exclusion. Intracellular pH during metabolic inhibition was determined with the fluorescent dye 2',7'-bis-(2-carboxyethyl)-5(and-6) carboxyfluorescein tetraacetomethoxymethyl ester. H2O2 consumption, a measure of H2O2 scavenging capability, was determined by a fluorescent assay. The viability and ATP levels of cells not subjected to metabolic inhibition were unaffected by these low concentrations of H2O2. Cells metabolically inhibited with glucose depletion and oligomycin were exquisitely sensitive to H2O2. Cells that were only deprived of glucose demonstrated no potentiation of injury, while cells subjected to mitochondrial inhibition with oligomycin alone also showed significant potentiation of oxidant injury. H2O2 consumption was not affected by metabolic inhibition. Conditions associated with mitochondrial inhibition consistently resulted in a decrease in intracellular pH. These experiments suggest that a synergism exists between metabolic inhibition and subsequent oxidant exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolic inhibition potentiates oxidant injury. 202 Jan 85

We intended to determine the levels of adenosine triphosphate (ATP) synthesis at the time when mitochondria ultrastructurally show flocculent densities in the matrix space. For this purpose, mitochondria were isolated from rat heart and rat liver after the tissues have been maintained under controlled ischemic conditions in vitro at 37 degrees C for intervals of 15, 30, 45, 60, 120, 180, and 240 (heart) min. The isolated mitochondria were tested for new ATP synthesis by luciferin/luciferase luminescence in the presence of substrate and adenosine 5'-diphosphate (ADP). The luminescence peaks were standardized and related to an external measure by measuring absorbance of ATP at 259 nm where the extinction coefficient is 15,400. Mitochondrial yield was monitored by measuring succinate dehydrogenase activity in the first homogenate and in the final mitochondrial pellet. Alternatively, cytochrome oxidase activity was used and the protein in the mitochondrial pellet was also determined. We found that the yield of mitochondria was above 53-54% in both liver and heart at 2 h of ischemia. Longer intervals were accompanied by lower yields. The ability to synthesize new ATP declined at different time intervals in ischemia of the heart compared to the liver. After 30 min ischemia, the synthesis in heart mitochondria is 18% of control, while the synthesis of liver mitochondria reaches 16% of control after 45 min of in vitro ischemia. Flocculent densities in heart mitochondria appeared at 45 min ischemia in vitro and in vivo, and at 60 min in liver mitochondria. We conclude that the decline of ATP synthesis is a significant early change in mitochondria and antedates the appearance of flocculent densities.
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PMID:Measurement of ATP synthesis and flocculent matrix densities in mitochondria as a function of 'in vitro' ischemia in the heart and liver of rats. 222 5

For the validation of volume-selective 1H and 31P NMR spectroscopy of the brain methods are required that allow high resolution quantitative mapping of tissue pH and metabolites on intact brain slices. The following techniques are proposed for this purpose. Tissue pH is imaged on cryostat sections of in situ frozen brains, using umbelliferone as a fluorescent pH indicator (Csiba et al, Brain Res 289, 334-337 (1983]. Regional tissue ATP content is measured in adjacent cryostat sections, using the luciferine/luciferase system of fireflies for evoking substrate-specific bioluminescence (Kogure and Furones Alonso, Brain Res. 154, 273-284 (1978]. Lactate content is imaged in a similar way by inducing substrate-specific bioluminescence with lactate dehydrogenase and luciferase from vibrio Fischeri (Paschen, J. Cereb. Blood Flow Metab. 5, 609-612 (1985]. The spatial resolution of these techniques is better than 100 mu, as exemplified in experimental brain tumors and brain infarct of cats. The applicability of biochemical mapping for the validation of NMR spectroscopy was tested in a global brain ischemia model of cat by correlating surface coil 31P and 1H spectra with the corresponding regional biochemical data, measured in the sensitive volume of the coil. Correlation coefficients were r = 0.907, 0.852 and 0.924 for pH, lactate and ATP, respectively. These results demonstrate that the biochemical measurements obtained by bioluminescence and fluoroscopic imaging correlate closely with the NMR data and, therefore, are appropriate for the validation of more complex applications, such as volume-selective spectroscopy of brain infarcts or tumors.
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PMID:Imaging of brain tissue pH and metabolites. A new approach for the validation of volume-selective NMR spectroscopy. 270 7

Cellular ATP levels are determined by the rates of ATP production and ATP hydrolysis. Both phenomena are affected by ischemia. Mitochondrial enzymes are damaged, inhibiting this organelle's ability to make ATP. Mitochondria are also uncoupled by ischemia and have the ability to hydrolyze ATP. We designed a series of experiments to determine whether decreased production or increased hydrolysis of ATP was the primary effect of mitochondrial damage. Rat hearts were subjected to 45 min of warm ischemia in order to induce irreversible cell damage. ATP or ADP was injected into cuvettes containing mitochondria isolated from normal myocardium or myocardium damaged by ischemia. Luciferin-luciferase, which fluoresces in the presence of ATP, was also added to the tubes as an indicator of ATP levels. Mixtures of uncoupled and coupled mitochondria were made and compared with the mitochondria damaged by ischemia. The results showed that mitochondria damaged by prolonged ischemia hydrolyze ATP more rapidly than normal mitochondria; however, normal mitochondria can easily compensate for increased ATP hydrolysis when in mixture with equal amounts of uncoupled mitochondria. These data suggests that the low cellular levels of ATP following irreversible ischemia are primarily due to decreased ATP synthesis and not to increased hydrolysis.
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PMID:ATP hydrolysis by ischemic mitochondria. 277 2

Endothelial cell dysfunction in ischemia may cause increased capillary permeability. We examined the effect of failing ATP synthesis, a major consequence of ischemia, on microfilaments--important structural determinants of the endothelial cell. Glycolytic and mitochondrial ATP synthesis in bovine pulmonary artery endothelial cells was inhibited by glucose depletion and 650 picomole (pmole) oligomycin/micrograms DNA, respectively. ATP levels were monitored with the luciferase-luciferin assay over a 2-hr time course followed by recovery for 1 hr after removal of the oligomycin and addition of 5.5 mM glucose. ATP levels fell to 83.6 +/- 63.8 pmole/micrograms DNA (n = 11) by 30 min, 26.9 +/- 13.8 pmole/micrograms DNA (n = 11) by 60 min, and 17.2 +/- 3.8 pmole/micrograms DNA (n = 6) by 120 min, whereas control uninjured cells had 541.3 +/- 196.8 pmole/micrograms DNA (n = 6) at 120 min. Fluorescence microscopy of microfilaments stained with rhodamine-phalloidin revealed progressive disassembly and shortening of the microfilaments in greater than 90% of cells over 60 min which correlated with the fall in ATP. Ultrastructural examination revealed that side to side aggregation of microfilaments had occurred over the 120-min time course. Two hours of glucose depletion (305.5 +/- 130.8 pmole ATP/micrograms DNA, n = 6) or oligomycin alone (480.0 +/- 90.1 pmole ATP/micrograms DNA, n = 6) failed to produce the dramatic fall in ATP or the microfilament changes. During cell recovery, there was a rapid reassembly of microfilaments, detected by fluorescence microscopy, which was nearly complete in 85-90% of cells by 45-60 min. ATP levels increased significantly (P = 0.002) to 96.1 +/- 36.8 pmole/micrograms DNA (n = 6) by 30 min. This model should provide insight into the pathogenesis and treatment of the capillary leak seen with ischemia.
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PMID:A cellular model of endothelial cell ischemia. 337 16

Three different pressure groups of rats, stroke-prone spontaneously hypertensive rats (SHRSP, 200-270 mmHg), stroke-resistant SHR (SHRSR, 160-240 mmHg), and Wistar rats (WR, 120-160 mmHg) were used to investigate the effect of prior existing hypertension on the severity of brain damage induced by ischemia. The cerebral ischemia was induced by bilateral common carotid artery ligation (BLCL) and the survival rate, cerebral blood flow, cerebral energy metabolites (ATP, lactate c-AMP) and water content were measured. Colloidal carbon perfusion was also performed. Sixteen-week-old male rats were used. The survival rate was observed until 24 hours after BLCL. Cerebral blood flow was measured in parietal cortex by hydrogen clearance method. ATP was measured by luciferin-luciferase method, and lactate by enzymatic method using LDH. c-AMP was measured by radioimmunoassay. Brain water content was measured by freeze-dry method. These measurements were done for animals surviving 6 hours of BLCL. Colloidal carbon perfusion was done according to Ames' Method. The survival rate was lower in the hypertension group. The survival of SHRSP and SHRSR were 20% compared to 71% in WR after 24 hours of BLCL. The cerebral circulation of SHRSP fell abruptly and was near to zero after one hour of BLCL. In SHRSR this fall of cerebral blood flow was prominent in the rats of higher blood pressure. On the other hand there was no apparent fall of cerebral blood flow in WR after BLCL. The cerebral energy metabolites. ATP and c-AMP showed the lowest level in SHRSP which had the negative correlation to blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Experimental cerebral ischemia after bilateral common carotid artery ligation in SHRSP, SHRSR and Wistar rats: correlation between blood pressure and degree of ischemia]. 609 92

The influence of total ischemia on the formation of products of anaerobic metabolism was investigated in canine hearts in vitro. Contents of organic acids were quantitatively analyzed by gas chromatography-mass spectrometry, and high energy phosphate compounds were determined using the luciferin-luciferase enzyme system. During a 10-min period of total ischemia, myocardial creatine phosphate significantly decreased, while ATP remained unchanged as compared with preischemic values. Both 10 min and 60 min of ischemia induced significant increase in tissue succinic acid levels. In contrast, a significant increase in myocardial lactic acid content was only induced with 60 min of ischemia. The data obtained indicate that the accumulation of succinic acid may be regarded as a potential metabolic marker of myocardial total ischemia.
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PMID:Myocardial metabolic markers of total ischemia in vitro. 789 60

Inflammation and ischemia--reperfusion tissue injury are important pathophysiologic processes with a wide spectrum of clinical presentations; the enzyme xanthine dehydrogenase/oxidase (XDH/XO) is thought to play a key role in ischemia--reperfusion injury. Recent studies have shown the transcriptional regulation of XDH/XO by cytokines (Dupont et al., 1992, J. Clin. Invest. 89, 197-202). In the present study, the 5' structure of the XDH/XO gene and characterization of its promoter are undertaken providing an initial step to further elucidate the regulatory mechanism(s) of this enzyme. XDH/XO cDNA from rat bone marrow macrophage has been isolated and used to screen a rat genomic library in order to identify and characterize the promoter of the XDH/XO gene. By Southern analysis, XDH/XO was found to be a single copy gene in the rat genome. Primer extension, RNase protection, and anchor-PCR studies indicate the presence of multiple start sites within a 65 bp window located some 20-85 bp upstream of the translation initiator (ATG). Functional studies of the sequences up to 116 nt upstream of the translational start site, which encompasses the several transcriptional start sites, indicate that this region is sufficient to drive the expression of a luciferase reporter gene and is presumed to represent the promoter. Neither a TATA box nor a GC-rich region are present in close proximity to any of the transcriptional start sites; however, sequences with homology to known initiator elements are found within this 116 bp fragment. Several possible regulatory elements, including a NF-IL6 motif, are also located upstream of the transcriptional start site. This study represents the first description of the XDH/XO promoter from a vertebrate system.
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PMID:Identification of the rat xanthine dehydrogenase/oxidase promoter. 820 9


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