UMLS:C0022116 - FACTA Search

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Query: UMLS:C0022116 (ischemia)
91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

L-Propionyl-carnitine is known to improve the recovery of myocardial function and metabolic parameters reduced in the course of ischemia-reperfusion of the heart. The mechanism of this protective effect of L-propionyl-carnitine is not fully understood. The purpose of this study was to elucidate the effects of L-propionyl-carnitine in Langendorff perfused rat hearts subjected to 40 min of ischemia followed by 20 min of reperfusion. We tested the hypothesis that L-propionyl-carnitine suppresses generation of oxygen radicals and subsequent oxidative modification of myocardial proteins during reperfusion. Our data show that the protective effect of L-propionyl-carnitine in the course of ischemia-reperfusion is highly significant in terms both of mechanical properties of the heart (developed pressure) and of high-energy phosphates (ATP, creatine phosphate). Myocardial creatine phosphokinase (CPK) activity decreased in the course of the reperfusion period. The loss of CPK activity was partially prevented by L-propionyl-carnitine. Two other effects were observed when L-propionyl-carnitine was present in the perfusion solution: (i) the reperfusion-induced sharp increase in oxidative protein modification was completely prevented as detected by the formation of protein carbonyls, and (ii) generation of hydroxyl radicals was significantly inhibited as detected by the formation of the adducts with the spin trap 5,5-dimethyl-1-pyrroline-1-oxide. We conclude that the protective effect of L-propionyl-carnitine against ischemia-reperfusion injury of the heart is at least due in part to its ability to suppress the development of oxidative stress and free radical damage.
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PMID:Free radical scavenging is involved in the protective effect of L-propionyl-carnitine against ischemia-reperfusion injury of the heart. 165 37

The aim of this study was to determine whether acute changes in [Mg2+]free occur during increased hydrolysis of cytosolic ATP, and whether these changes were of sufficient magnitude to be involved in the modulation of myocardial metabolism. 31P-NMR was used to estimate free cytosolic Mg2+ levels ([Mg2+]free) during hypoxia, isoproterenol stimulation, and graded low-flow ischemia in crystalloid perfused, isovolumic rat hearts. Cytosolic [Mg2+]free was calculated to be 0.73 +/- 0.12 mM in control hearts (100 mmHg hydrostatic pressure, 95% O2, n = 18). Cytosolic [Mg2+]free increased gradually during 10 min periods of hypoxia (65%, 50%, 35%, 5% O2), and 20 min infusions of isoproterenol (0.4, 3.0, 75 nM), to maximum values greater than 250% of control (P less than 0.05). During 8 min periods of graded low-flow ischemia (12.0, 7.2, 5.3, 3.4, and 1.6 ml/min/g), [Mg2+]free did not change significantly. [Mg2+]free displayed an inverse linear correlation with total cytosolic [ATP] during isoproterenol infusion (r = 0.87), and an exponential correlation during hypoxia (r = 0.82). The data indicate that acute changes in cytosolic [Mg2+]free can occur during conditions of net ATP hydrolysis although changes in ATP alone do not appear to be solely responsible for the changes in [Mg2+]free. Since the magnitude of the changes in [Mg2+]free are sufficient to alter equilibria of enzymes such as creatine kinase and myokinase, it is possible that these changes are involved in the acute modulation of myocardial metabolism.
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PMID:Cytosolic free magnesium in stimulated, hypoxic, and underperfused rat heart. 165 49

This study was made in a canine isolated gracilis muscle model to measure directly the free radicals, to predict the severity of ischemia and reperfusion injury of the skeletal muscle by measuring its surface pH (mspH), and to determine the effect of Coenzyme Q10 (CoQ10) in reducing the extent of muscle injury. Animals were divided into three groups: group A (control, n = 10), group B (untreated, n = 10), and group C (CoQ10 treated, n = 10). In both groups B and C, 5 hr ischemia followed by 40 min of reperfusion was made. Free radicals were measured directly by electron spin resonance spectrometer (ESR) and mspH was measured using a pH microprobe. Serum creatine phosphokinase (CPK) was estimated before ischemia, 5 and 30 min after reperfusion. The extent of muscle injury was evaluated morphologically by Evan's blue dye exclusion test. ESR intensity in group B was 0.55 +/- 0.19 and decreased to 0.30 +/- 0.04 in group C (P less than 0.01). Rate of recovery of mspH was higher in group C (7.16 +/- 0.06) compared to group B (6.88 +/- 0.11, P less than 0.01) and CPK in group C was less (847 +/- 381 IU/liter) than in group B (1356 +/- 519 IU/liter, P less than 0.05) after 30 min of reperfusion. In group C the morphological muscle injury was less (37.8 +/- 5%) compared to group B (56.7 +/- 3.6%, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Free radical injury in skeletal muscle ischemia and reperfusion. 166 96

The calcium-entry blocker isradipine was tested in a closed-chest pig model for chronic myocardial infarction. Ischemia was evoked in anesthetized pigs (25-35 kg) by inflating a catheter balloon in the left anterior descending coronary artery for at least 45 min. Hemodynamic monitoring and signal averaging of X, Y, and Z electrocardiographic leads were performed (150 beats, filtered at 50 Hz). After reperfusion, all animals developed an accelerated idioventricular rhythm and high creatine kinase (CPK) plasma levels. Coronary venous purines and catecholamines increased transiently. Two hours after reperfusion, heart rate was elevated from the initial 87.5 +/- 6.3 to 126 +/- 6.4 beats/min (p less than 0.01) and the pressure-rate product (PRP, an index of oxygen demand) from 9,530 +/- 630 to 11,950 +/- 790 mm Hg/min (p less than 0.05). After 2 weeks, six surviving pigs had a decreased stroke volume (98 +/- 18 versus the initial 124 +/- 14 microliters/kg, p less than 0.05), a prolonged high-frequency signal-averaged QRS duration (81.2 +/- 6.5 versus 65.7 +/- 2.9 ms, initially; p less than 0.05), and ventricular tachycardias (VTs), inducible by programmed electrical stimulation (PES). After the infusion of isradipine (1 microgram/kg/min for 30 min), the cardiac index increased from 92 +/- 14 to 133 +/- 8.7 ml/min.kg (p less than 0.02). Even at a higher heart rate, the PRP dropped from 12,600 +/- 1,900 to 10,560 +/- 1,400 mm Hg/min (p less than 0.05). Sustained monomorphic tachycardias were inducible in five pigs before and in three pigs after isradipine, and no deterioration of the signal-averaged electrocardiogram parameters was found.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of isradipine on hemodynamic parameters and ventricular tachycardia in healed myocardial infarction. 168 21

Local inhibition of angiotensin-converting enzyme (ACE, kininase II) produces both attenuation of angiotensin (Ang) II generation and bradykinin (BK) degradation. To delineate the participation of BK in the cardioprotective actions of ACE inhibitors, experiments were performed in rats and dogs with cardiac ischemia-reperfusion injuries. (I) In rat isolated perfused working hearts with regional myocardial ischemia, BK in concentrations as low as 1 X 10(-9) M increased coronary flow (CF) and reduced the incidence and duration of reperfusion ventricular fibrillation (VF). In addition, enzyme activities of lactate dehydrogenase (LDH) and creatine kinase as well as lactate output were decreased in the venous effluent of BK-perfused hearts, which also showed improved cardiodynamic and metabolic parameters. Even concentrations of BK lower than 1 X 10(-10) M, which were without influence on coronary flow, exerted comparable beneficial metabolic effects connected with reduced incidence and duration of VF. Combined perfusions with threshold concentrations of BK (1 X 10(-12) M) and the ACE inhibitor ramiprilat (2.58 X 10(-9) M), which were ineffective given alone, resulted in a marked cardioprotective effect. Perfusion with Ang II (1 X 10(-9) M) aggravated reperfusion arrhythmias and worsened myocardial metabolism. BK perfusion prevented this deterioration in a concentration-dependent manner, whereas the Ang II receptor antagonist saralasin was only marginally effective. The BK antagonist D-Arg-[Hyp2, Thi5,8, D-Phe7]-BK (1 X 10(-5) M) completely abolished the cardioprotective effects of BK or the ACE inhibitor. However, higher concentrations of BK (1 X 10(-7) M) or ramiprilat (2.58 X 10(-5) M) competitively reversed these properties of the BK antagonist. (II) In anesthetized dogs, BK was infused into the coronary artery in a dose of 1 ng/kg/min during occlusion (90 min) and reperfusion (30 min) of the left descending coronary artery (LAD)--a dose without effects on cardiovascular parameters. In line with the findings in isolated ischemic rat hearts, BK infusion reduced LDH activities and lactate concentrations in the coronary sinus blood, whereas myocardial tissue levels of glycogen and energy-rich phosphates were increased in the infarcted area. The cardioprotective effects produced by perfusion with BK or by reduction of BK degradation through local interference with ACE favor a role for BK in ischemia-reperfusion injuries in rats and dogs.
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PMID:Local inhibition of bradykinin degradation in ischemic hearts. 169 70

The cardioprotective effects of a novel antiinflammatory drug, ONO-3144 (ONO), on ischemic-reperfused myocardium were investigated using an in situ pig heart model. Heart was subjected to 2 h of regional ischemia, with the final 1 h having superimposed global cardioplegic arrest followed by 1 h of reperfusion. ONO (20 microM) was administered after the arrest at the onset of reperfusion. Left ventricular developed pressure (LVDP), maximum rate of rise of left ventricular pressure (LV dp/dt), and left ventricular end-diastolic pressure (LVEDP) were measured under isovolumic conditions to assess cardiac contractility and compliance. ONO improved LVDP and LV dp/dt, and reduced LVEDP after 60 min of reperfusion compared to control. This drug also improved segment shortening and end-diastolic length significantly after 15 and 60 min of reperfusion. Slight improvements in oxygen consumption and creatine kinase (CK) release were also noted. In addition, ONO reduced lipid peroxidation and thromboxane formation but enhanced the production of prostaglandins. In vitro studied demonstrated ONO to be effective scavengers for both hydroxyl (OH.) and hypohalite (OCL.) radicals. The results suggest that myocardial reperfusion injury that developed after ischemic arrest was reduced significantly by ONO. This drug inhibited such injury, probably by directly scavenging potentially harmful radicals such as OH. and OCI., which are generated in ischemic-reperfused myocardium.
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PMID:Prevention of myocardial reperfusion injury in experimental coronary revascularization following ischemic arrest by a novel antiinflammatory drug, ONO-3144. 170 95

We have investigated the contribution of the renin-angiotensin system to the damage caused by 40-min global ischemia in the isolated rat heart. A converting enzyme inhibitor, enalaprilat (70 nM), an angiotensin II receptor antagonist, compound 89 (2 microM), and an inhibitor of rat renin, CGP 44099A (20 nM), given before ischemia reduced the median duration of ventricular fibrillation on reperfusion to a similar extent (5.53, 5.72, and 5.14 min, respectively, compared to 13.98 min in the control group) but had no effect on creatine phosphokinase release (22.2 +/- 2.6, 22.1 +/- 6.8, and 24.1 +/- 3.6, IU/30 min, respectively, compared to 19.9 +/- 1.9 IU/30 min) or recovery or left ventricular developed pressure (67 +/- 6, 73 +/- 7 and 71 +/- 6%, respectively, compared to 66 +/- 3% after 30 min reperfusion). The increase in coronary resistance and left ventricular diastolic pressure on reperfusion was not affected by any of the agents. All three agents also tended to reduce the duration of ventricular fibrillation when given only on reperfusion. We conclude that angiotensinogen is present in the rat heart and it is converted to angiotensin I by a renin or a renin-like aspartic proteinase. The angiotensin I is converted to angiotensin II by converting enzyme. The angiotensin II formed is an important mediator of postreperfusion ventricular fibrillation in the isolated rat heart but does not contribute to the reduction in mechanical function produced by global ischemia in this preparation.
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PMID:Involvement of the renin-angiotensin system in ischemic damage and reperfusion arrhythmias in the isolated perfused rat heart. 171 94

In this study, the effect of bradykinin or saline infusion during ischemia and reperfusion on electrical stability, 2 weeks after myocardial infarction, was assessed. Acute myocardial infarction was induced in 21 pigs by a transluminal occlusion of the left coronary artery with a catheter balloon, inflated for 45 min. Bradykinin was administered by a 30-min infusion that started after 30 min of coronary occlusion and was continued until 15 min after reperfusion. Although creatine kinase levels in bradykinin-treated animals were significantly lower (p less than 0.001), 2 week survival was not different between groups. In survivors, the filtered QRS (ventricular deflection) duration (detected using signal-averaged electrocardiography) was significantly prolonged in saline-treated pigs, whereas in bradykinin-treated pigs this prolongation was prevented. The terminal voltage of the QRS complex was significantly lower in saline-treated pigs than in bradykinin-treated pigs. These two parameters signify an improved electrical stability after bradykinin treatment. Refractory periods in saline-treated hearts were longer than in bradykinin-treated hearts (106 +/- 10% vs. 95 +/- 13%, p less than 0.05). Also, current thresholds in the infarct border zones showed a greater variance in saline-treated hearts (p less than 0.001), pointing toward more tissue heterogeneity of the infarct border zone. Programmed electrical stimulation showed a trend toward reduced inducibility of sustained ventricular tachycardia in bradykinin-treated hearts. Therefore, bradykinin improves electrical stability weeks after experimental myocardial infarction.
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PMID:In vivo effect of bradykinin during ischemia and reperfusion: improved electrical stability two weeks after myocardial infarction in the pig. 171 27

The paper discusses if it is advisable to use kallikrein-kinin system inhibitors earlier. A total of 122 patients with acute ischemia and infarction of the myocardium were studied. Contrykal and heparin infused in the prehospital period, followed by hospital treatment are optimal to prevent vascular wall lesions, maximally retain retrograde blood flow, and substantially reduce the size of myocardial infarction. Therapy with protease inhibitors proved to be most beneficial within the first 2 hours of the disease, as evidenced by a profound improvement in the clinical course of myocardial infarction, a decrease in ECG and precordial mapping signs of ischemia, a positive change in myoglobin and MB creatine phosphokinase levels, and a significant reduction in the rehabilitative period.
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PMID:[Rationale for using kinin system inhibitors in patients with acute ischemia and infarction of the myocardium during the prehospital phase]. 171 6

Isolated canine hearts were preserved at 4 degrees C with multi-dose cardioplegic solution every hour for 6 hours. Reperfusion was observed for 2 hours under cross-circulation without cardiotonic drugs. The aprotinin group (n = 8), which received cardioplegic solution with added aprotinin (150 KIU/mL), was compared with the control group (n = 6). The increase in tissue adenosine triphosphate and total adenine nucleotide content during reperfusion was significant in the aprotinin group; there was no change in the control group, and the levels at the end of reperfusion tended to be higher in the aprotinin group than in the control group. Tissue adenosine diphosphate levels remained unchanged in both groups. Tissue adenosine monophosphate levels declined during reperfusion in both groups and were slightly lower in the control group. Tissue levels of cyclic adenosine monophosphate remained unchanged in the aprotinin group whereas they increased during ischemia and declined significantly during reperfusion in the control group. Tissue levels of cyclic guanosine monophosphate declined during reperfusion in both groups without difference. Creatine phosphate levels recovered in both groups without difference. Serum cyclic guanosine monophosphate concentration tended to be lower in the aprotinin group than in the control group. Serum creatine kinase-MB level increased slightly during reperfusion in both groups without difference. N-acetyl-beta-D-glucosaminidase levels were significantly suppressed during reperfusion in the aprotinin group as compared with the control group. These results suggest that aprotinin is effective in preserving adenine nucleotide and adenosine triphosphate levels and in stabilizing tissue cyclic adenosine monophosphate levels in prolonged hypothermic cardioplegic preservation followed by reperfusion.
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PMID:Effect of aprotinin to improve myocardial viability in myocardial preservation followed by reperfusion. 171 31

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