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)

Ischemic-induced cell injury results in rapid duration-dependent actin-depolymerizing factor (ADF)/cofilin-mediated disruption of the apical microvilli microfilament cores. Because intestinal microvillar microfilaments are bound and stabilized in the terminal web by the actin-binding protein tropomyosin, we questioned whether a protective effect of tropomyosin localization to the terminal web of the proximal tubule microfilament cores is disrupted during ischemic injury. With tropomyosin-specific antibodies, we examined rat cortical sections under physiological conditions and following ischemic injury by confocal microscopy. In addition, Western blot analysis of cortical extracts and urine was undertaken. Our studies demonstrated the presence of tropomyosin isoforms in the proximal tubule microvillar terminal web under physiological conditions and their dissociation in response to 25 min of ischemic injury. This correlated with the excretion of tropomyosin-containing plasma membrane vesicles in urine from ischemic rats. In addition, we noted increased tropomyosin Triton X-100 solubility following ischemia in cortical extracts. These studies suggest tropomyosin binds to and stabilizes the microvillar microfilament core in the terminal web under physiological conditions. With the onset of ischemic injury, we propose that tropomyosin dissociates from the microfilament core providing access to microfilaments in the terminal web for F-actin binding, severing and depolymerizing actions of ADF/cofilin proteins.
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PMID:Renal ischemia induces tropomyosin dissociation-destabilizing microvilli microfilaments. 1507 95

The novel calmodulin (CaM) antagonist DY-9760e (3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate) with an apparent neuroprotective effect in vivo preferentially inhibits neuronal nitric oxide synthase (nNOS), Ca2+/CaM-dependent protein kinase IIalpha (CaMKIIalpha), and calcineurin in vitro. In the present study, we investigated the molecular mechanism underlying its neuroprotective effect with the gerbil transient forebrain ischemia model, by focusing on its inhibition of these Ca2+/CaM-dependent enzymes. Post-ischemic DY-9760e treatment (5 mg/kg, i.p.) immediately after 5-min ischemia significantly reduced the delayed neuronal death in the hippocampal CA1 region. CaMKIIalpha was transiently autophosphorylated immediately after reperfusion with concomitant sustained decrease in its total amounts in the Triton X-100-soluble fractions. Calcineurin activity, accessed by the phosphorylation state of dopamine- and cAMP-regulated phosphoprotein of Mr 32,000 (DARPP-32) at Thr34, was elevated at 6 h after reperfusion. Post-treatment of DY-9760e had no effects on both CaMKIIalpha and DARPP-32 phosphorylation at 6 h after reperfusion. However, DY-9760e significantly inhibited nitrotyrosine formation, as a biomarker of NO, and in turn, peroxynitrite (ONOO-) production. These results suggest that DY-9760e primarily inhibits Ca2+/CaM-dependent neuronal NOS, without any effects on CaMKII and calcineurin, and the inhibition of NO production possibly accounts for its neuroprotective action in brain ischemic injury.
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PMID:The post-ischemic administration of 3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate (DY-9760e), a novel calmodulin antagonist, prevents delayed neuronal death in gerbil hippocampus. 1535 85

Plasma membrane disruption is a characteristic feature of cell death induced by hypoxia or ischemia. Here, we investigated whether analysis of tissue electrical impedance allows detection of ongoing cell membrane rupture and necrotic cell death in hypoxic or ischemic myocardium. Twenty-eight isolated rat hearts were submitted to 5 h of ischemia (n = 8) or hypoxia (n = 20). Myocardial electrical impedance and lactate dehydrogenase (LDH) release were monitored. The time course of hypoxia-induced cell death was modified by altering pH (pH 7.4 or 6.4, 5 h) or by adding 3 or 10 mM glycine. Ischemia and hypoxia induced an increase in electrical impedance, followed by a plateau, and later a reduction. During hypoxia, LDH release started after a prolonged lapse of time (80.00 +/- 8.37 min at pH 7.4 and 122.50 +/- 11.82 min at pH 6.4). The onset of LDH release was followed by the onset of the late reduction in electrical impedance, and both were delayed by acidic pH (P < 0.05) and by glycine (P < 0.05). The times of onset of LDH release and of late electrical changes were significantly correlated (r = 0.752, P < 0.001). In separate experiments, induction of sarcolemmal rupture with Triton X-100 (n = 6) mimicked the late effects of ischemia or hypoxia on tissue impedance. The protective effects of glycine and acidosis on membrane disruption were confirmed (propidium iodide) in energy-deprived HL-1 cardiomyocytes. These results describe for the first time a late fall in electrical impedance in myocardium submitted to prolonged oxygen deprivation and demonstrate that this fall allows detection of ongoing cell necrosis.
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PMID:Effect of sarcolemmal rupture on myocardial electrical impedance during oxygen deprivation. 1549 23

Connexin-protein interactions are believed to be critical for the regulation of gap junctional intercellular communication and for the function of gap junctions formed by these complexes. We have primarily used immunoprecipitation strategies to investigate whether connexin43 binds to selected signaling and cytoskeletal proteins and whether connexin43-protein binding is altered in cultured astrocytes exposed to chemical ischemia/hypoxia, a treatment that resembles ischemia in vivo. Chemical ischemia/hypoxia induced marked dephosphorylation of connexin43, which was accompanied by increased association of connexin43 with c-Src, ERK1/2, and mitogen-activated protein kinase phosphatase-1 and by decreased association between connexin43 and beta-actin. Moreover, we found that endogenous c-Src in normal astrocytes exists primarily in the Triton X-100-soluble membrane fraction, distinct from the Triton-insoluble fraction, which contains gap junctions. After chemical ischemia/hypoxia, c-Src appeared in the Triton-insoluble fraction and was co-immunoprecipitated with connexin43, suggesting that chemical ischemia/hypoxia induced translocation of c-Src to the Triton-insoluble fraction and association with connexin43. Furthermore, the "dephosphorylated" form of connexin43 was immunoprecipitated by a phosphotyrosine antibody, suggesting tyrosine phosphorylation of connexin43 by c-Src. In addition, the association between connexin43 and c-Src was blocked by inhibition of connexin43 dephosphorylation, suggesting that the interaction between connexin43 and c-Src can be regulated by alterations in the phosphorylation state of connexin43. These results identify new binding partners for connexin43 and demonstrate that interactions between connexin43 and protein kinases and phosphatases are dynamically altered as a consequence of connexin43 phosphorylation.
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PMID:Regulation of connexin43-protein binding in astrocytes in response to chemical ischemia/hypoxia. 1561 29

Ischemia results in increased phosphorylation of NMDA receptors. To investigate the possible role of lipid rafts in this increase, lipid rafts and post-synaptic densities (PSDs) were isolated by the extraction of rat brain synaptosomes with Triton X-100 followed by sucrose density gradient centrifugation. Lipid rafts accounted for the majority of PSD-95, whereas SAP102 was predominantly located in PSDs. Between 50 and 60% of NMDA receptors were associated with lipid rafts. Greater than 85-90% of Src and Fyn were present in lipid rafts, whereas Pyk2 was mainly associated with PSDs. Lipid rafts and PSDs were isolated from animals subjected to 15 min of global ischemia followed by 6 h of recovery. Ischemia did not affect the yield, density, flotillin-1 or cholesterol content of lipid rafts. Following ischemia, the phosphorylation of NR1 by protein kinase C and tyrosine phosphorylation of NR2A and NR2B was increased in both lipid rafts and PSDs, with a greater increase in tyrosine phosphorylation occurring in the raft fraction. Following ischemia, NR1, NR2A and NR2B levels were elevated in PSDs and reduced in lipid rafts. The findings are consistent with a model involving close interaction between lipid rafts and PSDs and a role for lipid rafts in ischemia-induced signaling pathways.
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PMID:Increased phosphorylation and redistribution of NMDA receptors between synaptic lipid rafts and post-synaptic densities following transient global ischemia in the rat brain. 1577 18

The heart utilizes primarily fatty acids for energy production. During ischemia, however, diminished oxygen supply necessitates a switch from beta-oxidation of fatty acids to glucose utilization and glycolysis. Molecular mechanisms responsible for these alterations in metabolism are not fully understood. Mitochondrial acyl-CoA dehydrogenase catalyzes the first committed step in the beta-oxidation of fatty acids. In the current study, an in vivo rat model of myocardial ischemia was utilized to determine whether specific acyl-CoA dehydrogenases exhibit ischemia-induced alterations in activity, identify mechanisms responsible for changes in enzyme function, and assess the effects on mitochondrial respiration. Very long chain acyl-CoA dehydrogenase (VLCAD) activity declined 34% during 30 min of ischemia. Loss in activity appeared specific to VLCAD as medium chain acyl-CoA dehydrogenase activity remained constant. Loss in VLCAD activity during ischemia was not due to loss in protein content. In addition, activity was restored in the presence of the detergent Triton X-100, suggesting that changes in the interaction between the protein and inner mitochondrial membrane are responsible for ischemia-induced loss in activity. Palmitoyl-carnitine supported ADP-dependent state 3 respiration declined as a result of ischemia. When octanoyl-carnitine was utilized state 3 respiration remained unchanged. State 4 respiration increased during ischemia, an increase that appears specific to fatty acid utilization. Thus, VLCAD represents a likely site for the modulation of substrate utilization during myocardial ischemia. However, the dramatic increase in mitochondrial state 4 respiration would be predicted to accentuate the imbalance between energy production and utilization.
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PMID:Inhibition of very long chain acyl-CoA dehydrogenase during cardiac ischemia. 1585 May 53

Decreased Ca2+ responsiveness of the myofilaments underlies myocardial stunning. Given that cross-bridge cycling is a major determinant of myofilament behavior, we quantified cross-bridge cycling rate in stunned myocardium. After stabilization, rat hearts were subjected to 20 min of no-flow global ischemia and 30 min of reperfusion at 37 degrees C. Control hearts were perfused continuously at 37 degrees C for 60 min. Trabeculae were dissected and chemically skinned with 1% Triton X-100. The muscles were then activated with solutions of varied Ca2+ concentration ([Ca2+]). Force-[Ca2+] relations, rate of force redevelopment after release (k(tr)), muscle stiffness (k(m)), and myofilament ATP consumption were determined. Maximal Ca2+-activated force (Fmax) was depressed in stunned myocardium (49 +/- 5 vs. 82 +/- 5 mN/mm2, P < 0.01). Western immunoblotting showed degradation of troponin I in stunned myocardium. The k(tr) at Fmax was significantly increased in stunned muscles (19.82 +/- 2.74 vs. 13.19 +/- 0.96 s(-1), 22 degrees C, P < 0.01; 7.49 +/- 0.52 vs. 5.81 +/- 0.54 s(-1), 10 degrees C, P < 0.05). The ratio of k(m) measured at 100 Hz over that at 1 Hz, during Fmax, is lower in stunned muscles (8.22 +/- 1.56 vs. 12.94 +/- 0.71, P < 0.05). In comparison with k(m) at rigor, k(m) at Fmax is significantly lower in the stunned group (78.82 +/- 6.11 vs. 93.27 +/- 3.03%, P < 0.05). Myofilament ATP consumption at Fmax did not change in stunned muscles (5,901 +/- 952 vs. 5,596 +/- 972 pmol x microl(-1) x min(-1), P = 0.49). These results show that cross-bridge cycling is increased in stunned myocardium. Such increases are likely the result of increased transition rate from force-generating states to non-force-generating states. Thus stunned myocardium still maintains ATP consumption in spite of lower force development, rationalizing the long-standing paradox of decreased force but unchanged oxygen consumption in the postischemic heart.
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PMID:Increased cross-bridge cycling rate in stunned myocardium. 1617 65

Although the cardioprotective role of carbon monoxide (CO) has been studied against myocardial ischemia-reperfusion (I/R) injury, the role of coronary endothelium and underlying mechanism in carbon monoxide-induced cardioprotection is not well understood in isolated heart. The present study was designed to determine the role of coronary endothelium in CORM-2-mediated cardioprotection during I/R injury in isolated rat heart. Preconditioning with 30microM/l and 50microM/l of CORM-2 for 10min markedly reduced lactate dehydrogenase (LDH) and creatinin kinase (CK) levels in coronary effluent after global ischemia. There was also a significant improvement in coronary flow rate, heart rate, cardiodynamic parameters and marked attenuation in infarct size. However, protective effect was abolished when hearts were pretreated with 100microM CORM-2. We observed that pretreatment with L-NAME (100microM/l), a nitric oxide synthase (NOS) inhibitor did not affect protection by CORM-2 (50microM/l). On the other hand pretreatment with Triton X-100 (0.05% for 20s) to denude endothelium before CORM-2 treatment followed by I/R injury showed similar cardioprotection. Moreover, pretreatment with K(ATP) channel inhibitor, glibenclamide almost completely reversed the cardioprotective effect of CORM-2 in endothelium-denuded hearts. These results indicate that cardioprotection by CORM-2 is highly concentration-dependent, independent of coronary endothelium and cardioprotective effect might be attributed to the activation of K(ATP) channel present on vascular smooth muscle cell (VSMC).
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PMID:Cardioprotective effect with carbon monoxide releasing molecule-2 (CORM-2) in isolated perfused rat heart: Role of coronary endothelium and underlying mechanism. 2039 2

Membrane rafts, rich in sphingolipids and cholesterol, are membrane microdomains important in neuronal domain-specific signaling events such as during axonal outgrowth and neuronal death. The present study seeks to determine the spatiotemporal association of several axonal guidance signaling molecules with membrane rafts. These molecules are Neuropilin-1 (NRP-1), Fer Kinase, and collapsin response mediator proteins (CRMPs), which are known to have important functions in axonal outgrowth and neuronal death caused by cerebral ischemia. Mice were subjected to sham or a 1h unilateral middle cerebral artery occlusion (MCAO) followed by a time course of reperfusion up to 24h. Brain cortices were separated and membrane rafts were extracted based on their insolubility in Triton X-100 and separation by sucrose gradient fractionation. We demonstrate the early and transient induction of NRP-1 and CRMP-2 in membrane rafts in both ipsilateral and contralateral hemispheres, in contrast to an early, but sustained elevation of Fer kinase and other CRMPs (1, 3, 4, 5) in response to unilateral MCAO. The fact that NRP1/Fer kinase/CRMP-2 co-localize in membrane rafts early during ischemic injury suggests that the membrane rafts may form a scaffold to support and initiate NRP1/Fer/CRMP-2-mediated signal transduction in neuronal damage response during ischemia-reperfusion. Further understanding of the time-specific and membrane domain-specific protein-protein interaction may lead to the identification of therapeutic targets for stroke.
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PMID:Transient and bilateral increase in Neuropilin-1, Fer kinase and collapsin response mediator proteins within membrane rafts following unilateral occlusion of the middle cerebral artery in mouse. 2049 26

ASK1 is a cellular stress-responsive MAPKKK which activates the JNK and p38 MAPK pathways that play a key role in the response of cardiac myocytes to redox stress following ischemia/reperfusion. ASK1 becomes incorporated into high-molecular weight complexes upon activation but this has not been investigated in cardiac myocytes. Here we examine the distribution of ASK1 in neonatal rat cardiomyocytes undergoing simulated ischemia and reperfusion. Simulated ischemia or redox stress in neonatal cardiac myocytes causes the translocation of ASK1 to distinct punctate cytoplasmic structures that are insoluble in Triton X-100. The translocation event is not dependent on ASK1 kinase activity, occurs subsequent to activation and is reversible upon removal of the cell stress. The structures to which ASK1 translocates in cardiac myocytes do not appear to correspond to the previously described ASK1 signalosome reported in other cell types.
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PMID:Reversible translocation of ASK1 to a Triton-X100 insoluble cytoplasmic compartment during cardiac myocyte cell stress. 2207 Mar 84


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