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)

1. Changes of structural proteins in experimental and human myocardial infarction were studied by the determination of myosin- and actomyosin-ATPase activities and gel electrophoretic analysis in the presence of sodium dodecyl sulfate (SDS). 2. In animal experiments using dogs, the relative amounts of myosin and alpha-actinin decreased at 24 to 48 hours after coronary ligation, became lowest at 72 hours, and remained at this level for 2 weeks and returned to almost normal value at 28 days. 3. Myosin- and actomyosin-ATPase activities decreased rapidly during 24 to 48 hours after ligation with temporary increase in their activities in the initial stage of ischemia and followed the similar time course as that of the amounts of myosin and alpha-actinin. 4. SDS gel electrophoretic analysis of structural proteins of infarcted tissues of the human hearts obtained from 5 cadavers showed also marked decrease of the contents of myosin and alpha-actinin with relative preservation of actin, tropomyosin and troponin-T.
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PMID:Changes of cardiac structural proteins in myocardial infarction. 92 15

Mitochondrial respiration, succinate dehydrogenase coenzyme Q reductase, and myosin B were investigated in ischemic myocardium from experimental myocardial infarction in dogs. Respiratory control ratio of mitochondria was impaired by ischemia at 60 min after coronary ligation, and oxygen consumption was inhibited 120 min later. Enzyme activity of succinate dehydrogenase coenzyme Q reductase was decreased at 6 hr after coronary ligation. Calcium ion sensitivity of myosin B declined 12 hr after coronary ligation. However, adenosine triphosphatase activity of myosin A from infarcted myocardium was not different from that of the intact one. These results suggest that interaction in the sequence of enzyme complexes was first impaired in ischemic myocardium and that deterioration of enzyme activity was then manifested.
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PMID:Relationship between energy liberation and utilization in ischemic cardiac muscle. 103 51

It has been demonstrated that the V3 cardiac myosin isozyme has a higher efficiency and consumes less oxygen in doing mechanical work than the V1 myosin isozyme. The purpose of the present study is to investigate the functional and metabolic responses to ischemia following reperfusion of the hypothyroid heart, in which ventricular myosin isozyme is shifted from V1 predominance to V3 predominance. The heart was perfused by the working heart method for 15 min, and then global ischemia was induced for 10, 20 and 30 min with pacing at a rate of 320/min until cardiac cessation. The ischemic heart was reperfused for 30 min. The extent of recovery of pressure-rate product after reperfusion, following 20 min of ischemia in the hypothyroid heart, was higher than that in the control heart (p less than 0.01). The level of adenosine triphosphate (ATP) declined more slowly in the hypothyroid heart than in the control heart. The level of ATP and energy charge potential in the hypothyroid heart reperfused after 20 min of ischemia were higher than those in the reperfused control heart (p less than 0.01, p less than 0.05, respectively), though they did not differ from each other in preischemia. There were no significant differences in the levels of tissue lactate between the 2 hearts during ischemia and reperfusion. The recovery rate of the coronary flow of the 2 hearts did not differ from each other significantly. These data suggest that there is probability of the V3 predominant heart recovering from ischemic damage to the metabolism and cardiac function better than the V1 predominant heart because the transformation of myocardium, due to an increase in V3 into a slower but more efficiently working muscle results in conservation of tissue ATP during ischemia.
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PMID:Functional and metabolic responses to ischemia in the isolated perfused hypothyroid rat heart. 138 36

The influence of hypothermia on the development of the ischemic disorders was studied using allotransplantation of the rat skeletal muscle (m. lumbricalis) to the anterior chamber of the eye after different period of ischemia. The morphological and immunohistochemical (monoclonal antibodies to heavy chain of the fast myosin, PAP-method) data were found confirming that hypothermia (2-4 degrees C) prolongs the period of the ischemic disorders first appearance by 5 h (from 6 to 11 h) if compared with development of ischemia in the muscle at 21-23 degrees C.
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PMID:[Effects of hypothermia on the development of ischemic lesions of skeletal muscles in rats]. 139 78

AMP deaminase, which hydrolyses AMP to inosine 5'-monophosphate (IMP) and NH3 at high rates during excessive energy demands in skeletal muscle, is activated when bound to myosin in vitro. We evaluated AMP deaminase binding in vivo during muscle contractions to assess whether binding 1) is inherent to deamination and found only with high rates of IMP production or simply coincident with the contractile process and 2) requires cellular acidosis. AMP deaminase activity (mumol.min-1.g-1) was measured in the supernatant (free) and 10(4)-g pellet (bound) homogenate fractions of muscle of anesthetized rats after in situ contractions to determine the percent bound. In resting muscle, nearly all (approximately 90%) AMP deaminase is free (cytosolic). During contractions when energy balance was well maintained, binding did not significantly differ from resting values. However, during intense contraction conditions that lead to increased IMP concentration, binding increased to approximately 60% (P less than 0.001) in fast-twitch and approximately 50% in slow-twitch muscle. Binding increased in an apparent first-order manner and preceded initiation of IMP formation. Further, binding rapidly declined within 1 min after cessation of intense stimulation, even though the cell remained extremely acidotic. Extensive binding during contractions was also evident without cellular acidosis (iodoacetic acid-treated muscle). Thus the in vivo AMP deaminase-myosin complex association/dissociation is not coupled to changes in cellular acidosis. Interestingly, binding remained elevated after contractions, if energy recovery was limited by ischemia. Our results are consistent with myosin binding having a role in AMP deaminase activation and subsequent IMP formation in contracting muscle.
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PMID:AMP deaminase binding in contracting rat skeletal muscle. 151 75

Clinical heart preservation is currently limited to only 4-6 hr, while the kidney, liver, and pancreas can tolerate 24-48 hr of cold ischemia. A fundamental difference between these organs is that the heart is contractile, containing large quantities of actin and myosin, and is susceptible to contracture-induced injury caused by energy deprivation. We have quantified and correlated the onset of contracture with levels of ATP and glycogen during cold storage in rabbit hearts flushed with UW solution, with and without 1 mM calcium (Ca), or 3 mM iodoacetate (IAA). A fluid-filled left ventricular balloon was used to generate pressure-volume curves (compliance) at 1, 6, 12, 18, and 24 hr of cold storage. Onset of contracture occurred in UW stored hearts at 18 hr, contracture in hearts exposed to Ca occurred between 6 and 12 hr. Compliance was significantly less in hearts exposed to Ca at 12, 18, and 24 hr (P less than .01) than in hearts without Ca. ATP levels were well maintained for up to 18 hr in the hearts preserved in UW solution (78%), but fell more rapidly in the presence of Ca at 12 hr (P less than .005), 18 hr (P less than .005), and 24 hr (P less than .05). In comparison, the ATP supply of the liver and kidney was exhausted by only 4 hr of cold storage. Onset of myocardial contracture correlated with a decrease in ATP to less than 80% of control, and contracture accelerated ATP decline 3-6-fold. IAA caused nearly complete myocardial contracture and ATP depletion within 2 hr. Isolated heart function was 77% and 73% at 6 and 12 hr of storage, but fell to 54% and 42% at 18 and 24 hr, respectively, coinciding with development of contracture. We conclude that ischemic contracture in this model is a major cause of myocardial damage during cold storage, and is accelerated by the presence of Ca. Other organs can be successfully stored despite exhaustion of ATP reserves. Thus successful cold-storage of the heart is highly ATP-dependent. Since cold storage inevitably leads to ATP depletion, extension of myocardial ischemic tolerance will depend on either reversible inhibition of ATP hydrolysis during storage, reversible uncoupling of contracture development from ATP depletion, or maintaining ATP production by continuous hypothermic perfusion.
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PMID:Limitations of heart preservation by cold storage. 173 22

The ability of muscle fibers to survive the ischemic condition was examined. After 0 to 11 h of ischemia of the rat m. lumbricalis was transplanted to the anterior chamber of the rats eye. Using a morphological and immunohistochemical (monoclonal antibodies to heavy chain of the fast myosin, PAP-method) methods it was revealed that population of surviving muscle fibers reduced significantly beginning from 6 h of ischemia. After 9 h of ischemia there were no muscle fibers in the transplant but one could observe the new formed muscle tubules. It is concluded that up to 6 h the muscle fibers of m. lumbricalis ischemia still preserve the ability to recover.
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PMID:[An immunohistochemical study of the rat m. lumbricalis at different periods of ischemia after its allograft into the anterior chamber]. 181 May 2

The isolated working rabbit heart preparation was used to study whether the "contractile machinery" remains unchanged in globally stunned myocardium. The function of the heart has been measured in nonischemic and postischemic conditions. The effect of isoprenaline or calcium chloride administration in both conditions was also studied. Myocardial contractile function was significantly depressed after 20-min global ischemia and returned to normal after CaCl2 and supranormal values after isoprenaline administration. From hearts used in experiments myofibrils were prepared and their ATPase activity was determined. It was observed that myofibrils prepared from "stunned" myocardium showed about 50% increase in ATPase activity in the presence of CaCl2. Subjection of the heart to ischemia caused a decrease in calcium sensitivity of the myofibrillar ATPase. Myofibrils obtained from ischemic hearts but subjected to isoprenaline or CaCl2 administration exhibited increased calcium sensitivity over that of control heart. These effects were accompanied by changes in the extent of phosphorylation of troponin I (TNI) and myosin light chains. The modification of contractile apparatus in the postischemic period described in this paper may contribute to the overall mechanism of myocardial stunning.
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PMID:Contractile proteins in globally "stunned" rabbit myocardium. 183 10

Radiolabeled monoclonal antibody fragments to myosin, specifically 111In-labeled antimyosin, have been shown to be effective for imaging areas of myocardial infarct. To determine if 111In-labeled antimyosin can be used to assess the extent of necrosis, we compared the tissue retention fraction of 111In-labeled antimyosin with the amount of creatine kinase (CK) released from the isolated, perfused, interventricular rabbit septum after an intervention to induce tissue necrosis. 111In-labeled antimyosin was injected and tissue radioactivity was monitored for a 60-min period under control conditions. Effluent samples were also collected during this period and assayed for CK content. After a period of Ca2+ depletion followed by Ca2+ repletion, 111In-labeled antimyosin was again injected, and washout and CK data were collected. Comparison of the changes in 111In-labeled antimyosin retention fraction from control to intervention with the corresponding increase in CK released during intervention resulted in a correlation coefficient of 0.83. To corroborate the findings of the Ca2+ depletion followed by repletion experiments, further experiments were conducted in which zero-flow ischemia followed by reperfusion was used as a means of introducing necrosis in the septum. The resulting correlation coefficient between CK release and 111In-labeled antimyosin retention fraction was 0.82. The results of these experiments indicate that 111In-labeled antimyosin can be used to quantitatively estimate the extent of necrosis in the rabbit septum, as determined by CK release, and endorse the potential use of tracer kinetics in humans for quantitation of myocardial necrosis in vivo.
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PMID:Correlation of myocardial necrosis with kinetics of 111In-labeled myosin-specific antibody in isolated rabbit septum. 187 60

Fab fragments of antibodies specific for cardiac myosin have been labeled with indium-111 and injected intravenously into animals and into patients with heart transplants. The antibodies, developed by Khaw, Haber, and co-workers, localize in cardiac myocytes that have been damaged irreversibly by ischemia, myocarditis, or the rejection process. After clearance of the labeled antibody from the cardiac blood pool, planar imaging or single photon emission computed tomography is performed. Scintigrams reveal the uptake of the labeled antimyosin in areas of myocardium undergoing transplant rejection. In animal studies, the degree of antimyosin uptake appears to correlate significantly with the degree of rejection assessed at necropsy. In patients, the correlation between scans and pathologic findings from endomyocardial biopsy is not as good, possibly because of sampling error in the endomyocardial biopsy technique. The scan results at 1 year correlate with either late complications (positive) or benign course (negative). Current limitations of the method include slow blood clearance, long half-life of indium-111, and hepatic uptake. Overcoming these limitations represents a direction for current research. It is possible that from these efforts a noninvasive approach to the diagnosis and evaluation of cardiac transplantation may evolve that will decrease the number of endomyocardial biopsies required to evaluate rejection. This would be particularly useful in infants and children.
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PMID:Antimyosin imaging in cardiac transplant rejection. 188 96


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