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

The author of this report has studied peroxide lipid and evoked potentials of the spinal cord during ischemia and after reperfusion. In addition, he has studied effects of vitamin E (V.E.) upon ischemic spinal cord. The ischemia of the spinal cord was experimentally produced by clamping the thoracic aorta of Wistar rats and subsequently removing the clamps. Wistar rats were given diet containing 2 IU/100 g (control group) or 50 IU/100 g (V.E. group) of alpha-tocopherol acetate for 6 weeks before experiments. In the V.E. group the quantity of thiobarbituric acid reactive substance (TBARS) in the spinal cord after clamp removal was lower than the control group. The V.E. content in the spinal cord indicated a negative correlation to the TBARS values. The evoked spinal potentials in both groups disappeared due to spinal cord ischemia. The control group displayed wave form loss earlier than the V.E. group. It is conceivable that lipid peroxidation correlate to the tissue damage following spinal cord ischemia and reperfusion, and V.E. has the preventive effect to the damage.
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PMID:[Peroxide lipid and evoked spinal potentials in experimental spinal cord ischemia]. 258 41

Bioenergetic and hemodynamic consequences of cellular redox manipulations by 0.2-20 mM pyruvate were compared with those due to adrenergic stress (0.7-1.1 microM norepinephrine) using isolated working guinea-pig hearts under the conditions of normoxia, low-flow ischemia, and reperfusion. 5 mM glucose (+ 5 U/l insulin) + 5 mM lactate were the basal energy-yielding substrates. To stabilize left ventricular enddiastolic pressure, ventricular filling pressure was held at 12 cmH2O under all conditions; this preload control minimized Frank-Starling effects on ventricular inotropism. Global low-flow ischemia was induced by reducing aortic pressure to levels (20-10 cmH2O) below the coronary autoregulatory reserve. Reactants of the creatine kinase, including H+ and other key metabolites, were measured by enzymatic, HPLC, and polarographic techniques. In normoxic hearts, norepinephrine stimulations of inotropism, heart rate x pressure product, and oxygen consumption (MVO2) were associated with a fall in the cytosolic phosphorylation potential [( ATP]/[( ADP].[Pi]] as judged by the creatine kinase equilibrium. In contrast, infusion of excess pyruvate (5 mM) markedly increased [ATP]/[( ADP].[Pi]) and ventricular work output, while intracellular phosphate decreased; MVO2 remained constant under the same conditions. During reperfusion following ischemia, pyruvate effected striking and concentration-dependent increases in MVO2, phosphorylation potential, and inotropism. Pyruvate dehydrogenase flux was augmented during reperfusion hyperemia followed by near-complete recoveries of [ATP]/([ADP].[Pi]), contractile force, heart rate x pressure product, and MVO2 in the presence of 5-10 mM pyruvate. Pyruvate also attenuated ischemic adenylate degradation. Omission of glucose from the perfusion medium rendered pyruvate ineffective in postischemic hearts. Similarly, excess lactate (5-15 mM) or acetate (5 mM) failed to reenergize reperfused hearts and severe depressions of MVO2 and inotropism developed despite the presence of glucose. Apparently, subcellular redox manipulations by pyruvate dissociated stimulated mitochondrial respiration and increased inotropism from low cytosolic phosphorylation potentials. This was evidence against the extramitochondrial [ADP].[Pi]/[ATP] ratio being the primary factor in the control of mitochondrial respiration. The mechanism of pyruvate enhancement of inotropism during normoxia and reperfusion is probably multifactorial. Thermodynamic effects on subcellular [NADH]/[NAD+] ratios are coupled with a rise in the cytosolic [ATP]/[( ADP].[Pi]) ratio at constant (normoxia) or increased (reperfusion) MVO2.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pyruvate-enhanced phosphorylation potential and inotropism in normoxic and postischemic isolated working heart. Near-complete prevention of reperfusion contractile failure. 270 62

Proton nuclear magnetic resonance (NMR) spectroscopy of perchloric acid tissue extracts has been used to follow serial postischemic changes in the levels of metabolites in the hippocampus, cerebellum, frontal lobes, and parietal/occipital lobes in a rat model of short-duration (10 minutes) forebrain ischemia. Shortly (10 minutes, 1 hour) after the ischemic insult, the levels of the amino acids alanine and gamma-aminobutyric acid are elevated and that of glutamate is depressed in all regions except the cerebellum. The levels of these species return to control values by 24 hours postischemia. No changes are observed in the levels of aspartate or N-acetylaspartate. Greatly elevated levels of acetate 10 minutes postischemia, particularly in the hippocampus, may be due in part to metabolic degradation of fatty acids released due to membrane breakdown. Elevated levels of lactate persist for up to 7 days postischemia, suggesting that normal mitochondrial functioning is not fully restored following the ischemic insult.
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PMID:Nuclear magnetic resonance study of regional metabolism after forebrain ischemia in rats. 271 4

The role of protein kinase C (C kinase) in the left ventricular relaxation impaired by global ischemia was investigated in anesthetised dogs. Left ventricular global ischemia model was made by coronary blood flow reduction and atrial pacing (100-180 beats/min). By this maneuver, the time constant T and left ventricular end-diastolic pressure (LVEDP) were increased in a pacing-rate dependent manner. Intracoronary infusion of H-7, an inhibitor of C kinase, suppressed the magnitudes of the increments of T and LVEDP, while intracoronary infusion of 12-O-tetradecanoyl-phorbol-13-acetate, an activator of C kinase, enhanced the increases of T and LVEDP caused by ischemia. In non-ischemic group, H-7 did not influenced T and LVEDP. The results indicate that C kinase is activated by myocardial ischemia and enhances impairment of left ventricular relaxation.
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PMID:[The role of protein kinase C in left ventricular relaxation impaired by global ischemia]. 278 Nov 57

The effect of two different combined treatments with vitamin E acetate and vitamin C on infarct size and recovery of regional myocardial function was investigated in ischemic, reperfused porcine hearts. The left anterior descending coronary artery was distally ligated in 30 thoracotomized pigs for 45 minutes followed by 3 days of reperfusion. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic (dye technique) myocardium. Regional myocardial function was assessed by sonomicrometry. Ten pigs received vitamin E acetate (12 gm intravenously three times for 1 week) before ischemic and vitamin C (4.4 gm intravenously) before reperfusion (therapy A). Another 10 pigs were treated with vitamin E acetate (12 gm intraarterially) and vitamin C (4.4 gm intravenously) during ischemia (therapy B). An additional 10 pigs served as a control group. Global hemodynamics did not differ significantly among the groups before and during ischemia. Mean plasma concentrations of vitamin E amounted to 107 micrograms/ml in group A, 16 micrograms/ml in group B, and 0.9 micrograms/ml in the control group at the onset of reperfusion. Therapy A reduced the size of the infarct from 73 +/- 12% to 47 +/- 16% of the region at risk (p less than 0.005) and improved regional systolic shortening from 0 +/- 7% to 11 +/- 6% at 3 days after reperfusion (p less than 0.01). Therapy B decreased the size of the infarct to 64 +/- 9% of the region at risk (p = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Combined treatment with vitamins E and C in experimental myocardial infarction in pigs. 280 74

Ischemia-reperfusion activates polymorphonuclear leukocytes (PMN). Depletion of PMN has been shown to reduce the size of experimental myocardial infarction. We have studied whether PMN activated by phorbol myristate acetate (PMA) would depress function of the isolated rat heart, and if this effect was mediated by oxygen free radicals (OFR). Cells and/or drugs were added to the perfusate into the aortic cannula for 10 min, followed by a 30 min recovery period. Oxygen free radicals formation was verified by chemiluminescence (CL). PMA-activated PMN (n = 13) caused CL response of 27,493 +/- 5113 counts (mean +/- S.E.M.) and reduced left ventricular developed pressure (LVDP) to 30 +/- 9% and coronary flow (CF) to 49 +/- 7% of the baseline value at the end of the observation period. Addition of super-oxide dismutase (SOD) and catalase (CAT) (n = 11) reduced the CL response to 5623 +/- 806 counts, but did not influence either LVDP (36 +/- 15%) or CF (51 +/- 18%). Addition of thiourea (TU) to the activated cell suspension (n = 8) further reduced the CL response (3663 +/- 474 counts), and LVDP was 86 +/- 5% and CF was 87 +/- 3%. When TU + SOD + CAT was mixed with PMN + PMA (n = 11), the CL was almost abolished (117 +/- 21 counts) and LVDP was 73 +/- 8% and CF was 94 +/- 6%. When CF was reduced (n = 7) alike the CF reduction in the hearts receiving PMA + PMA, LVDP was not significantly changed at the end of the observation period (75 +/- 6%). Unactivated PMN (n = 8) caused minor response of LVDP and CF, similar to PMN + PMA + TU and PMN + PMA + SOD + CAT + TU. PMA alone (n = 8) was cardiotoxic and caused changes similar to PMN + PMA. This effect was not inhibited by scavengers (n = 6). The supernatant of the PMN + PMA suspension (n = 7) did not impair cardiac function, suggesting that no free PMA was available after mixing with PMN. We conclude that activated PMN in the coronary circulation depressed cardiac function and increased vascular resistance due to OFR production.
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PMID:Functional impairment in isolated rat hearts induced by activated leukocytes: protective effect of oxygen free radical scavengers. 281 Mar 77

We examined the effects of MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-one), a novel free radical scavenger and an inhibitor of ischemia-induced brain edema, on monoamine metabolism in the brains of both normal and ischemic rats. In normal rats, 3 mg/kg i.v. MCI-186, a dose that prevents ischemic brain edema, had no significant effect on brain concentrations of dopamine, norepinephrine, 5-hydroxytryptamine, or their metabolites. After the injection of 5 microliters of 3% polyvinyl acetate into the left internal carotid artery, concentrations of 3,4-dihydroxyphenylacetic acid and homovanillic acid markedly increased, but that of norepinephrine decreased, in the left telencephalon of embolized rats compared with control rats injected with vehicle; the concentration of 5-hydroxyindoleacetic acid also increased slightly. These effects were maximal 2 hours after embolization. The turnover rate of dopamine between 6 and 8 hours after embolization was significantly higher but that of norepinephrine was slightly lower than that in vehicle-treated rats. When rats were treated with 3 mg/kg i.v. MCI-186 immediately after the injection of polyvinyl acetate, the embolization-induced changes in monoamine metabolism were less marked. Our results suggest that MCI-186 attenuates ischemia-induced changes in brain monoamine metabolism, probably due to its free radical scavenging action, although it has no marked effect in normal rats.
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PMID:Effect of MCI-186 on ischemia-induced changes in monoamine metabolism in rat brain. 281 91

The protective effect of angiotensin-converting enzyme inhibitors (ACEI) on myocardial ischemia and reperfusion damage was estimated in rat hearts, both in vivo and in vitro. Enalapril 2.5 mg/kg ip pretreatment at 24 and 5 h before coronary occlusion, significantly blunted the rise of CPK (445 +/- 151 vs 649 +/- 244 mu/ml, P less than 0.05) and improved electrocardiogram (ECG) 8 h after coronary occlusion. In global ischemia and reperfusion ex vivo, enalapril improved contractility (0.9 +/- 0.2 vs 0.3 +/- 0.3 g, P less than 0.05) and coronary flow (15.6 +/- 3.3 vs 11.9 +/- 3.1 ml/min/g, P less than 0.05), shortened significantly the duration of reperfusion arrhythmia (3.1 +/- 2.7 vs 9.7 +/- 8.1 min, P less than 0.05). In Langendorffs heart, captopril remarkably preserved force of contraction (2.1 +/- 0.4 vs 1.4 +/- 0.4 g, P less than 0.01) and coronary flow (2.7 +/- 0.5 vs 3.6 +/- 0.9 ml/min/g, P less than 0.05) in segmental infarction deteriorated by angiotensin I. Captopril 10(-5) M infusion reduced the release of CPK (435 +/- 112 vs 640 +/- 123 mu/min coronary flow, P less than 0.05). This action was almost completely abolished by pretreating and infusing with indomethacin. As a positive control, prostacyclin 5 X 10(-7) M infusion further reduced the release of CPK to 330 +/- 77 mu/min. It is concluded that angiotensin-converting enzyme inhibitor can protect both myocardial ischemia and reperfusion damage in rat hearts. The mechanism of protection was ascribed to reduced production of angiotensin II by ACE inhibition and increased prostacyclin release in the myocardium.
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PMID:Protective effects of captopril and enalapril on myocardial ischemia and reperfusion damage of rat. 282 45

The abilities of angiotensin converting-enzyme (ACE) inhibitors to suppress superoxide anion formation in vitro and to improve postischemic cardiac function in vivo were examined. Three sulfhydryl-containing ACE inhibitors, captopril, its stereoisomer SQ 14,534, and an analog, zofenopril (SQ 26,703) were compared with enalaprilat and teprotide, which lack the sulfhydryl group but inhibit ACE, and two compounds, N-2-mercaptopropionylglycine (MPG) and N-acetylcysteine (NAC), which contain a thiol moiety but are not ACE inhibitors, for suppression of free radical formation in vitro. The autooxidation of epinephrine to adrenochrome is mediated by superoxide anions and inhibited by captopril, SQ 14,534, and zofenopril, with similar IC50 values of 8 to 10 microM, but not by enalaprilat or teprotide (IC50 greater than 1000 microM). This reaction is also inhibited by MPG and NAC with IC50 values of 19 and 17 microM, respectively. In addition, captopril, MPG, or NAC, but not teprotide or enalaprilat, scavenge superoxide anion production by the purine-xanthine oxidase reaction and by canine neutrophils activated with phorbol myristate acetate. These results indicate that captopril scavenges superoxide anions in vitro independent of an action on ACE, which is probably related to the presence of a sulfhydryl moiety. Myocardial segmental function in the anesthetized, open-chest dog is altered during ischemia from active shortening to passive lengthening. Reperfusion after 15 min of ischemia does not restore active shortening within a 3 hr experimental period. Pretreatment of dogs with captopril intravenously (5 mg/kg) results in a 40% to 60% return to active shortening within 60 min of reperfusion. In contrast, equihypotensive doses of enalaprilat do not improve segmental function during reperfusion. Dogs given captopril immediately before restoring coronary blood flow show a similar return of function as that observed in animals treated with the drug before occlusion. SQ 14,534, the isomer of captopril, which is 100-fold less potent as an ACE inhibitor but equipotent in scavenging superoxide anions, also improves reperfusion-induced cardiac dysfunction when administered at reperfusion (5 mg/kg). Thus captopril improves postischemic contractile derangements by a mechanism independent of ACE inhibition. Restoration of blood supply to the ischemic myocardium provokes ventricular fibrillation in 37.5% of control dogs but in only 9% of those administered enalaprilat and 0% of captopril-treated animals. SQ 14,534 does not reduce the incidence of ventricular fibrillation (40%), indicating that the antifibrillatory actions may be related to ACE inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Does captopril attenuate reperfusion-induced myocardial dysfunction by scavenging free radicals? 283 9

The contribution of neutrophils to reperfusion injury after ischemia is not known. To determine the effect of neutrophils on the function of ischemic kidneys, we added purified human neutrophils during perfusion of isolated ischemic or nonischemic rat kidneys. Reperfusion of ischemic kidneys with neutrophils caused a distinct morphological lesion of vascular endothelial and smooth muscle cells and more functional injury than reperfusion with buffered albumin alone; with neutrophils, glomerular filtration rate (GFR) was 113 +/- 7 microliter.min-1.g-1, tubular sodium reabsorption (TNa) was 72 +/- 2%; without neutrophils, GFR was 222 +/- 18 microliter.min-1.g-1; TNa was 90 +/- 2%; both P less than 0.01 vs. reperfusion with neutrophils. In contrast, addition of neutrophils did not injure control kidneys, unless the neutrophil activator, phorbol myristate acetate, was also added. Two experiments suggested that O2 metabolites contributed to neutrophil-mediated injury to ischemic kidneys. First, reperfusion of ischemic kidneys with O2 metabolite-deficient neutrophils from a patient with chronic granulomatous disease did not cause more injury than reperfusion with buffered albumin alone. Second, simultaneous addition of the O2 metabolite scavenger, catalase, prevented the GFR and TNa decreases caused by neutrophils but did not decrease injury in the absence of neutrophils. We conclude that neutrophils by an O2 metabolite-dependent mechanism contribute to ischemia-reperfusion injury in the isolated perfused kidney.
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PMID:Neutrophils accentuate ischemia-reperfusion injury in isolated perfused rat kidneys. 284 13


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