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

1. Influence of ischemia on the biochemical properties of the sarcoplasmic reticulum (SR) was studied in the experimental myocardial infarction in the dog. 2. Ca2+ -uptake rate of SR decreased at around 90 minutes after coronary occlusion. This reduction was roughly in parallel with the reduction in the Ca+ -Mg2+ -stimulated ATPase activity. However, Ca2+ -binding rate of SR was kept within the range of that of the non-infarcted tissue through the time course of myocardial infarction. 3. Ca2+ -Mg2+ -stimulated ATPase activity decreased at around 3 hours after coronary occlusion to about 50% of that of the non-infarcted portion. 4. In SDS gel electrophoresis, the protein band with the largest molecular weight among three major components decreased at 3 hours after coronary occlusion, which is suggestive of ATPase. At 48 hours after coronary occlusion, the protein with the smallest molecular weight in the major proteins also decreased. 5. Ca2+ -uptake rate, Ca2+ -Mg2+ -stimulated ATPase activity and the substructural changes return to the normal level and pattern at around 28 days after coronary occlusion.
 ...
PMID:Studies of the cardiac sarcoplasmic reticulum in myocardial infarction. 15 53

Previous studies have shown degradation of cardiac structural proteins and disruption of the sarcolemma as a result of acute myocardial infarction. However, there is no evidence to date on changes in sarcolemmal membrane proteins induced by experimental subacute myocardial infarction. We studied subepicardial layers overlying myocardial infarct 4 days following ligation of the left anterior descending coronary artery in 12 dog hearts. We first demonstrated that this layer provides the anatomic-electrophysiologic substrate for reentrant arrhythmias using activation mapping techniques and histologic correlations. The makeup of membrane proteins was studied using SDS polyacrylamide gel electrophoresis, peptide mapping, and laser densitometry. Sarcolemmal membrane proteins were isolated by ultracentrifugation through a sucrose gradient. We found that a sarcolemmal polypeptide (MW 126,000; n = 12) in the normal tissues has a different mobility than the corresponding protein (MW 124,000; n = 12) of the ischemic tissues although their peptide analysis appeared similar, suggesting that the protein undergoes a post-translational modification. In addition, two proteins (MW 75,000; n = 12 and MW 88,000; n = 12) were present in greater amount in the ischemic than in the control tissues suggesting either acceleration in protein synthesis or slow down of degradation turnover. These results demonstrate that specific changes occur in membrane proteins subjected to ischemic insults which might be responsible for membrane alterations following ischemia and may contribute to the abnormal electrophysiologic properties and arrhythmia seen in vivo at this stage.
 ...
PMID:Changes in sarcolemmal proteins in subacute myocardial infarction in the dog. 130 6

Ubiquitin-protein conjugates in the hippocampus were analyzed by immunoblotting with a monoclonal anti-ubiquitin antibody. In the CA1 region, Triton X-100 insoluble ubiquitin-protein conjugates increased after 24 hr following 20 min of ischemia. When the total hippocampi were fractionated subcellularly, ubiquitin-protein conjugates increased in the particulate, especially in the mitochondrial fraction. The ubiquitin-protein conjugates were solubilized by SDS, or were partially solubilized by urea. The results indicate that insoluble ubiquitin-protein conjugates increase after ischemia.
 ...
PMID:Subcellular distribution of ubiquitin-protein conjugates in the hippocampus following transient ischemia. 132 64

Exposure of the vessel wall to hypoxemia is a central feature of ischemic cardiovascular disease. This led us to examine the perturbation of endothelial cell properties under hypoxia. An atmosphere of pO2 of 12 mmHg is not lethal to the endothelial cells for up to five days, but barrier function was impaired. Increased passage of macromolecule tracers were observed in time- and dose-dependent manner and electron microscopy demonstrated small gaps (0.5-1.0 micron) between cells. Expression of the anticoagulant cofactor thrombomodulin was also perturbed: thrombomodulin activity and antigen decreased in parallel. Northern blots showed almost complete suppression of thrombomodulin in hypoxic culture. Furthermore, synthesis of other proteins, such as fibronectin, was slightly enhanced under hypoxia. In addition to the suppression of these anticoagulant cofactor, hypoxic endothelial cell displayed a noval procoagulant activity distinct from tissue factor. Further study revealed that hypoxic endothelial cultures directly activated Factor X, as assessed by functional assays and SDS-PAGE. In addition to this no activation of Factor IX or prothrombin was observed. The hypoxia-induced Factor X activator was membrane-associated, required calcium to form Factor Xa, was inhibited by HgCl2 but not by PMSF, and had Km approximately 25 micrograms/ml. Co-incubation of hypoxic cultures with cycloheximide prevented the expression of this activity, suggesting that protein synthesis is required for its expression. These functional perturbations of endothelial cells were reversible following reoxygenation. These data indicate that hypoxia imposes a selective perturbation on endothelial cell function, suggesting the possible contribution of hypoxemia to vascular dysfunction in ischemia.
 ...
PMID:Modulation of endothelial function by hypoxia: perturbation of barrier and anticoagulant function, and induction of a novel factor X activator. 196 56

The effects of pronase and/or SDS pretreatment on Na+-Ca2+ exchange were studied in rat brain microsomal membranes. Pronase in concentrations that liberated 11% of the membrane proteins stimulated the Na+-Ca2+ exchange. When about 24% of the proteins were split off, the results did not differ from those in control experiments. When 40% or more of the proteins were solubilized, Na+-Ca2+ exchange was abolished. Pronase pretreatment did not change the Km value for Ca2+, it increased Vmax only. The effect of pronase was partially blocked by Trasylol. Neuraminidase had no effect on Na+-Ca2+ exchange. SDS pretreatment of the membranes inhibited Na+-Ca2+ exchange: when 25% of membrane proteins were solubilized with SDS, the Na+-Ca2+ exchange was abolished while the same amount of proteins split off with pronase did not change the rate of Na+-Ca2+ exchange as related to membrane proteins. Ischaemia lasting for 2-4 h or complete hypoxia which should stimulate endogenous proteinases due to the rise of free intracellular calcium did not influence the Na+-Ca2+ exchange. A decrease in Na+-Ca2+ exchange rate was observed when proteins with molecular weight between 45,000 and 20,000 were split off from the membranes. It is assumed that the Na+-Ca2+ antiporter is a polypeptide from the group of proteins within the above molecular weights.
 ...
PMID:Na+-Ca2+ exchange in rat brain microsomal membranes pretreated with pronase and/or SDS. 241 32

Total renal ischemia for various time intervals (0-50 min) resulted in the rapid and duration-dependent redistribution of polarized membrane lipids and proteins in renal proximal tubule cells. Following only 15 min of ischemia, apical membrane enrichment of NaK-ATPase, normally a basolateral membrane (BLM) enzyme, had increased (1.6 +/- 0.6 vs. 2.9 +/- 1.2, P less than 0.01). In vivo histochemical localization of NaK-ATPase showed reaction product throughout the apical microvillar region. PTH-stimulatable adenylate cyclase, another BLM protein, was also found in ischemic but not control apical membrane fractions. One dimensional SDS-PAGE showed four bands, present in control BLM and ischemic apical membranes, which could not be found in control apical membrane fractions. Immunohistochemical localization of leucine aminopeptidase (LAP) showed the enzyme was limited to the apical domain in control cells. Following ischemic injury (50 min), LAP staining could be seen within the cell and along the BLM. Following 24 hr of reperfusion, the BLM distribution of LAP was further enhanced. With cellular recovery from ischemic injury (5 days), LAP was again only visualized in the apical membrane. Duration-dependent alterations in apical and BLM lipids were also observed. Apical sphingomyelin and phosphatidylserine and the cholesterol-to-phospholipid ratio decreased rapidly while apical phosphatidylcholine and phosphatidylinositol increased. Taken together, these results indicate renal ischemia causes rapid duration-dependent reversible loss of surface membrane polarity in proximal tubule cells.
 ...
PMID:Characterization of ischemia-induced loss of epithelial polarity. 246 76

The muscle proteins of rabbits with the compartment syndrome caused by tourniquet were studied by SDS-polyacrylamide gel electrophoresis and the compartment pressure post-ischemia was measured. The post-ischemic pressure in the anterior compartment increased more than that in the deep-posterior compartment. The phoretic patterns of structural and soluble proteins changed after ischemia, and their degeneration appeared to depend on the degree of pressure increase. In ischemic contracture, the patterns of myosin light chains of type 1 fibers changed to those of type 2 fibers. This indicated the possibility of fiber type transformation from type 1 to type 2 in ischemic contracture.
 ...
PMID:[Experimental studies on a compartment syndrome caused by a tourniquet]. 339 50

The purpose of this study was to make clear the changes of structural proteins in the ischemic contracture muscle. Ischemia experiments were conducted on the forelimb of canines. Contracture proteins (myosin, actin, alpha-actinin) were isolated and analysed by using SDS-polyacrylamide gel electrophoresis. In the muscle group after 7-hour-ischemia, the muscle structural proteins were changed remarkably, along the time course after the release of tourniquet. After 7 days, myosin heavy chain decreased to 1/2 to 1/3 the original value. It was especially myosin heavy chain that changed remarkably among muscle structural proteins. Actin showed changes after 10-hour-ischemia.
 ...
PMID:[The study of structural proteins in the ischemic contracture muscle]. 343 76

Changes in the cardiac sarcolemma in myocardial infarction were studied by both determination of Na+-K+-ATPase activity and SDS gel electrophoretic analysis of sarcolemmal proteins in the canine heart. Ninety minutes after coronary ligation, Na+-K+-ATPase activity in ischemic myocardium was decreased significantly to approximately 36% of that of non-ischemic myocardium, and it remained at the lower level for 28 days. By SDS gel electrophoresis, reduction of the protein band with molecular weight of 111,000, which is suggestive of the main component of ATPase, was observed simultaneously with the reduction of Na+-K+-ATPase activity. These results indicate that ischemia for 90 minutes produces substructural changes in the sarcolemma indicating irreversible myocardial changes.
 ...
PMID:Studies on the Na+-K+-ATPase in myocardial infarction. 627 94

The effect of fatty acid and acylcarnitine on Ca2+ and Na+ transporting enzymes and carriers was studied in sealed cardiac sarcolemma vesicles of mixed polarity. Palmitoylcarnitine markedly reduced the Na+ gradient-induced Ca2+ uptake. Half-maximal reduction was obtained at 15 microM of the carnitine derivative. In a same concentration range palmitoylcarnitine caused a rapid release of accumulated Ca2+ when added to Ca2+-filled vesicles, which suggests that palmitoylcarnitine increases the permeability of the sarcolemma vesicles to Ca2+. A rapid release of Ca2+ was also observed if Ca2+ was taken up by action of the Ca2+ pump. The (Ca2+ + Mg2+)-ATPase, which most likely drives this active Ca2+ uptake, was 90% increased by 50 microM palmitoylcarnitine and evidence was presented that the acylcarnitine effect again was linked to an alteration of Ca2+ permeability of the vesicles. At the same concentration acylcarnitine was not able to unmask the latent protein kinase, so that probably the sarcolemma ATP permeability was not affected. Palmitoylcarnitine at 25 microM did not affect the ouabain-sensitive (Na+ + K+) -ATPase in native sarcolemma vesicles, however, it inhibited markedly if the enzyme was measured in SDS-treated vesicles. The effect of increased free fatty acid concentration on some of the sarcolemma transporting properties was tested by adding oleate-albumin complexes with different molar ratios to the sarcolemma vesicles. In contrast to molar ratios 1 and 5, the ratio of 7 was able to induce a rapid Ca2+ release and to inhibit (Na+ + K+)-ATPase in either native or SDS-treated vesicles markedly. 22Na release from 22Na-preloaded sarcolemma vesicles was shown to be stimulated by either palmitoylcarnitine (50 microM) or oleate-albumin complex (with a molar ratio of 7). The possible significance of the observed effects of lipid intermediates on ion permeability and (Na+ + K+)-ATPase activity in isolated sarcolemma vesicles for the derangement of cardiac cell function in ischemia is discussed.
 ...
PMID:The effect of lipid intermediates on Ca2+ and Na+ permeability and (Na+ + K+)-ATPase of cardiac sarcolemma. A possible role in myocardial ischemia. 632 91


1 2 3 4 5 6 7 Next >>