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)

This study examined the effect of inhaled nitric oxide (NO) on lung neutrophil accumulation and endothelial-dependent and -independent guanosine 3',5'-cyclic monophosphate (cGMP)-mediated mechanisms of pulmonary vasorelaxation after mesenteric ischemia-reperfusion (I/R) in mechanically ventilated rats. Inhaled NO (20 ppm) was administered in two protocols: 1) throughout mesenteric I/R and 2) during mesenteric reperfusion alone. Concentration-response curves were generated (10(-9) to 10(-8) M) for acetylcho-line (ACh), A23187, and sodium nitroprusside (SNP) in isolated pulmonary arterial rings preconstricted with phenylephrine. Lung neutrophil accumulation [myeloperoxidase assay (MPO)] was significantly increased from 2.4 +/- 0.2 units/g lung wt in controls to 10.3 +/- 0.4 after 1 h of superior mesenteric artery occlusion and 2 h of reperfusion. Lung MPO activity was not different from controls in rats receiving inhaled NO either 1) during mesenteric I/R or during mesenteric reperfusion alone. The concentration-response curves demonstrated significant impairment of pulmonary vasorelaxation by endothelial-dependent mechanisms (response to ACh and A23187) but not endothelial-independent pulmonary vasorelaxation (response to SNP) after mesenteric I/R. This pulmonary vasomotor dysfunction was prevented by administration of inhaled NO during either mesenteric I/R or during mesenteric reperfusion alone. We conclude that inhaled NO prevents lung neutrophil accumulation and pulmonary vascular endothelial dysfunction after mesenteric I/R.
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PMID:Inhaled nitric oxide prevents pulmonary endothelial dysfunction after mesenteric ischemia-reperfusion. 877 72

This study was aimed to examine properties and changes in nitric oxide synthase (NOS) activity and cGMP level during reperfusion after 5 min of brain ischemia in gerbils. Animals were treated 5 min before ischemia with NOS inhibitors: N-Nitro-L-arginine (NNLA), or 7-Nitroindazole (7-NI), or with the inhibitor of guanylate cyclase, LY 83583, or with hydrocortisone for 7 days before ischemia. Northern blot analysis was performed using specific cDNA for inducible NOS. It was observed that ischemia significantly enhances NOS activity and cGMP level. During reperfusion, biphasic increase in NOS activity and cGMP level took place with two peaks 15 min and 2 h after ischemia. NNLA, 7-NI, and LY 83583 eliminated enhancements of NOS activity and cGMP level, whereas glucocorticoid remained without effect. There was no activation of gene encoding inducible NOS (iNOS). Our results indicate that ischemia-reperfusion activates constitutive NOS. It is suggested that nitric oxide (NO) production during reperfusion is related to neuronal degeneration and that inhibitor of NOS offers a new therapeutical strategies.
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PMID:Biphasic enhancement of nitric oxide synthase activity and cGMP level following brain ischemia in gerbils. 878 13

The goal of these experiments was to determine whether the perturbation of ischemia-reperfusion has an age-dependent effect on subsequent endothelial cell production of nitric oxide. Three- and 35-d-old swine in the experimental group were exposed to 1-h partial ischemia (90% flow reduction) and 2-h reperfusion in vivo by creation and then removal of a mesenteric artery coarctation. Control subjects underwent exposure of the mesenteric artery only. After reperfusion, gut vascular resistance had increased 44 +/- 6% in 3-d-old, but had decreased 41 +/- 4% in 35-d-old subjects. At the completion of the in vivo portion of the protocol mesenteric artery was removed, and nitric oxide production was estimated in vitro, by measuring cGMP production by vessel segments or by measuring relaxation of phenylephrine-precontracted rings, both after stimulation of nitric oxide production by substance P or the calcium ionophore A23187. Compared with control, mesenteric artery segments from 3-d-old subjects demonstrated reductions in basal, substance P-stimulated (10(-8) M) and A23187-stimulated (10(-7) M) cGMP accumulation of 50 +/- 7%, 66 +/- 6% and 78 +/- 7%. Mesenteric artery segments from 35-d-old subjects demonstrated increases in basal, substance P-stimulated, or A23187-stimulated cGMP accumulations of 114 +/- 14%, 92 +/- 8%, or 78 +/- 9%. Compared with control, I/R rings from 3-d-old subjects demonstrated reductions in substance P-induced (10(-8) M) or A23187-induced (10(-7) M) relaxations of 56 +/- 7% or 30 +/- 7%. In contrast, 35-d-old ischemia-reperfusion rings demonstrated increases in substance P- or A23187-induced relaxation of 36 +/- 8% or 98 +/- 11%. It is concluded that ischemia-reperfusion has an age-dependent effect on endothelial production of NO within in vitro postnatal mesenteric artery and that these changes mirror the effects of ischemia-reperfusion on gut vascular resistance in vivo.
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PMID:The effects of ischemia-reperfusion on endothelial cell function in postnatal intestine. 882 99

Partial agonists at the strychnine-insensitive glycine sites coupled to N-methyl-D-aspartate (NMDA) receptors reduce both glutamate-induced neurotoxicity in vitro and ischemia-induced neurodegeneration in vivo. Paradoxically, sustained exposure of cultured cerebellar granule cell neurons to glycinergic ligands, including glycine and the glycine partial agonists (+/-)-3-amino-1-hydroxy-2-pyrrolidone, 1-aminocyclopropanecarboxylic acid (ACPC), and D-cycloserine, attenuates the neuroprotective effects of (+/-)-3-amino-1-hydroxy-2-pyrrolidone and ACPC. In the present study, we investigated the mechanisms responsible for this attenuated neuroprotection. Three NMDA receptor-mediated responses were examined after sustained exposure to ACPC: glutamate-induced neurotoxicity, NMDA-stimulated increases in cGMP levels, and NMDA-stimulated increases in [Ca+2]i. Consistent with previous findings, coincubation with ACPC blocked glutamate-induced neurotoxicity, whereas sustained (24 hr) exposure to ACPC attenuated its protective effects. Moreover, sustained exposure to ACPC caused an apparent approximately 2-fold increase in the potency of both glutamate to act as neurotoxin and NMDA to stimulate cGMP formation. Sustained exposure to ACPC also increased NMDA-stimulated [Ca+2]i approximately 3-fold compared with control granule cell cultures but did not affect basal [Ca+2]i. This apparent increase in glutamate sensitivity may be attributable to a change in NMDA receptor subunit composition as sustained ACPC exposure resulted in a approximately 2.5-fold increase in NMDA receptor 2C RNA levels, without concomitant changes in the amounts of RNA encoding the NMDA receptor 2A, 2B, or 1 subunit. This is the first demonstration that sustained exposure to a glycinergic ligand can alter the expression of RNAs encoding NMDA receptor subunits. Because glycinergic ligands are potential clinical candidates, these results may have important implications for the treatment of neurodegenerative disorders.
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PMID:Sustained exposure to 1-aminocyclopropanecarboxylic acid, a glycine partial agonist, alters N-methyl-D-aspartate receptor function and subunit composition. 884 14

It has been reported that reperfusion injury results in the diminished nitric oxide (NO) release from the pulmonary vascular endothelium. However, this mechanism is completely unknown. We examined the effect of superoxide dismutase (SOD) on NO release at reperfusion. A rabbit lung was perfused with Krebs-Henselit buffer in a recirculation system. Cyclic GMP (cGMP) content in the lung effluent from the left ventricle was assayed in a time-dependent manner. In the control group, the lung was immediately perfused without interventing ischemia. In the warm ischemia and reperfusion group, the lung was reperfused after 30 min of warm ischemia. In the SOD group, SOD (60,000 U and 120,000 U) was administered at reperfusion after warm ischemia. The cGMP release in the warm ischemia and reperfusion group significantly decreased compared with the control group. In the SOD group, cGMP release was reversed with increasing doses of SOD, and the cGMP content was significantly reversed at all time points with SOD administration of 120,000 U. The impairement of cGMP release by reperfusion injury was restored by SOD administration. This data suggests that NO release from the endothelium may be quenched by superoxide anion generated at reperfusion. In lung transplantation, efforts must be pursued to preserve the endothelial function such as NO pathway.
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PMID:[Effect of superoxide production on nitric oxide release from the pulmonary vascular endothelium during reperfusion after warm ischemia]. 891 Oct 42

Glutamate receptor antagonists are protective in animal models of focal cerebral ischemia. Lamotrigine (3,5-diamino-6-[2,3-dichlorophenyl]-1,2, 4-triazine) is an anticonvulsant drug that blocks voltage-gated sodium channels and inhibits the ischemia-induced release of glutamate. Experiments in primary neuronal cultures implicate nitric oxide (NO) as a mediator of glutamatergic neurotoxicity acting via N-Methyl-D-Aspartate (NMDA) receptors. The effect of glutamate release inhibitor, Lamotrigine upon NO and cGMP production has been examined in focal cerebral ischemia in rats. Focal cerebral ischemia was produced by the permanent occlusion of right middle cerebral artery (MCA) in urethane anesthetized rats. A number of indicators of brain NO production (nitrite, cGMP) were determined in ipsilateral and contralateral cerebral cortex and cerebellum after 0, 10, 60 min of focal cerebral ischemia. The same parameters were measured in rats treated with Lamotrigine (20 mg/kg, i.p.) 30 min before or just after the occlusion of the right MCA.
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PMID:Effects of Lamotrigine on brain nitrite and cGMP levels during focal cerebral ischemia in rats. 908 81

The stimulation of NMDA receptor activates NO dependent cGMP biosynthesis with dynamic and extent different for hippocampus and brain cortex. The significantly higher NO mediated cGMP level was observed in hippocampus than in brain cortex. NMDA receptor stimulation increases NO mediated cGMP formation about 8 fold in hippocampus and 2.5 fold in brain cortex as compared to basal value (2 mM CaCl2). The activity of NO synthase and the basal level of cGMP in unstimulated slices were only slightly higher in hippocampus then in brain cortex. The CA2+ calmodulin dependent NO synthase was found in brain membrane and cytosol fraction. The enzyme activity was not affected by glucocorticoids, even after 20 days of hydrocortisone treatment in a dose of 40 mg/kg b.w. Brain ischemia induced by ligation of both common carotid arteries in gerbils increases significantly NOS activities as well as the level of cGMP and putrescine but decreases mono-ADP-ribosylation of brain proteins during reperfusion period. The ischemia evoked changes of NOS/cGMP were eliminated by specific inhibitor of neuronal form of NOS, 7-Nitrodazole (7NI) administered in a dose of 25 mg/kg b.w. 5 min. before ischemia. This inhibitor has no effect on the level of putrescine enhanced during ischemia and also biphasically during reperfusion. The inhibitor of guanylate cyclase, LY 83583 administered in a dose of 6 mg/kg b.w. 5 min before ischemia diminishes not only the enhanced level of cGMP but also NOS activity stimulated by ischemia. These results indicate that activation of NMDA receptor stimulates more significantly NO/cGMP production in hippocampus than in brain cortex suggesting the role of NO in neuronal form of NOS and inhibitor of guanylate cyclase protect the brain against excessive production of nitric oxide and cGMP during ischemia-reperfusion. These compounds may offer a new strategy in the therapy of brain ischemia.
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PMID:NMDA receptor mediated nitric oxide dependent cGMP synthesis in brain cortex and hippocampus. Effect of ischemia on NO related biochemical processes during reperfusion. 910 Feb 45

Neurodegeneration associated with neurological disorders such as epilepsy, Huntington's Chorea, Alzheimer's disease, and olivoponto cerebellar atrophy or with energy failure such as ischemia, hypoxia, and hypoglycemia proceeds subsequent to overexposure of neurons to excitatory amino acids of which glutamate and aspartate may be quantitatively the most important. The toxic action of glutamate and aspartate is mediated through activation of glutamate receptors of the N-methyl-D-aspartate (NMDA) and non-NMDA subtypes. Antagonists for these receptors can act as neuroprotectants both in in vitro model systems (e.g., cultured neurons) and in vivo. Activation of receptors leads to an increase in the intracellular Ca++ concentration and also to an increase in other second messengers such as cGMP. Thus, Ca++ channel antagonists may have neuroprotective action under certain conditions.
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PMID:Role of Ca+2 and other second messengers in excitatory amino acid receptor mediated neurodegeneration: clinical perspectives. 918 41

Although several studies have demonstrated that nitric oxide appears to be cardioprotective and endothelin-1 (ET-1) deleterious in myocardial ischemia/reperfusion injury, their interactions in the intact heart are unknown. Therefore, coronary effluent and interstitial fluid ("transudate") levels of ET-1 and cyclic GMP, an indirect measure of nitric oxide production, were determined simultaneously in normoxic and reperfused hearts and compared with myocardial and coronary function. Rat hearts were buffer-perfused at 9 ml/min/g heart wet weight for 45 min (baseline), followed either by another 45 min of perfusion (normoxia), or 15 min of total global ischemia and 30 min reperfusion. Hearts received, from 42-90 min, either vehicle, the inhibitor of nitric oxide formation NG-nitro-L-arginine (L-NNA; 200 micromol/l), the nitric oxide donor S-nitroso-N-acetyl-DL-penicillamine (SNAP; 200 micromol/l), or the ET receptor antagonist PD 142893 (200 nmol/l). Both mediators were released preferentially into the vascular lumen which resulted in similar luminal and interstitial concentrations of cyclic GMP, but three-fold higher levels of ET-1 in tissue because of the higher effluent than transudate flow rate. L-NNA increased the release of ET-1 and worsened coronary function, whereas SNAP had opposite effects. On reperfusion, considerable functional impairment was observed, although levels of cyclic GMP both in the vascular and tissue compartment were not reduced, but even increased. Reperfusion functional impairment was aggravated after inhibiting the synthesis of nitric oxide, whereas SNAP restored cardiac and coronary function close to pre-ischemic level. Deterioration of function corresponded with an increased level, and improvement with a decreased level of intersitial ET-1 at the onset of reperfusion. PD 142893 was similarly cardioprotective as SNAP both in normoxia and reperfusion. These results suggest that in reperfusion, cardiac function is depressed, despite increased rather than decreased endogenous nitric oxide production, largely due to the prevalence of the deleterious effects of ET-1 which are overcome by antagonism of ET receptors or exogenous nitric oxide supplied by SNAP.
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PMID:Interaction of nitric oxide and endothelin-1 in ischemia/reperfusion injury of rat heart. 929 60

Nitric oxide (NO) is a mediator that modulates vessel wall tone and hemostatic-thrombotic balance. Platelet function is regulated by NO generated from platelets, endothelial cells and leukocytes. Nitric oxide has been shown to inhibit platelet adhesion, aggregation, and stimulate disaggregation of preformed platelet aggregates. Many of the effects of NO are mediated by its stimulation of guanylate cyclase and the formation of cyclic GMP and its subsequent transduction mechanism. In vivo, NO is likely to interact with prostacyclin, metabolites of ecto-nucleotidase, and lipoxygenase to modulate platelet function in a synergistic manner. An imbalance of NO production (deficiency or overproduction) has been implicated in the pathogenesis of various vascular disorders including thrombosis, atherosclerosis, septicemia, and ischemia-reperfusion injury. It is likely that some of detrimental effects of NO are mediated through its reaction with superoxide anion to form the potent oxidant, peroxynitrite. Nitric oxide gas and NO donors are used for the pharmacological treatment of various vascular disorders. Because inhaled NO has been documented to improve systemic oxygenation and reduce the need for extracorporeal membrane oxygenation, it has been widely used in neonates with severe hypoxemia. An inhibition of platelet function, resulting in a prolonged bleeding time, has been shown in adults receiving inhaled NO. Because bleeding complications may occur in high-risk infants, it is important to evaluate the effect of inhaled NO on platelet function and its correlation with clinical consequences such as intracranial hemorrhage. For these reasons, hemostasis should be carefully monitored during the administration of inhaled NO to critically ill neonates.
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PMID:Nitric oxide and platelet function: implications for neonatology. 935 13


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