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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The involvements of arachidonic acid metabolites in the development of ischemic brain edema and cerebral energy metabolism were investigated on the experimental ischemia and reperfusion model. The level of arachidonic acid in brain tissue increases especially on the ischemic insult, which is rapidly converted to prostaglandins and leukotrienes after the reperfusion. The drugs which modify the arachidonic acid metabolism were administrated to clarify the effect on ischemic brain edema and cerebral energy metabolism. Male stroke resistant spontaneously hypertensive rats (SHRSR) were subjected to incomplete ischemia for two hours by occlusion of both common carotid arteries with vascular clips, and reperfused for two hours. The drugs used are dexamethasone, indomethacin, trapidil and OKY-046. Indomethacin inhibits cyclooxygenase. Dexamethasone inhibits phospholipases by the production of lipocortin. OKY-046 inhibits thromboxane A2 synthetase. Trapidil inhibits thromboxane A2 synthetase and increases the level of 6-keto-PGF1 alpha. These drugs were administered 18 hours before, just after clipping on (1/2) and off (1/2). Brain water content, cerebral ATP and lactic acid levels were examined. In the saline treated group, the cerebral water content was increased after the reperfusion and reached its maximal level after two hours of the reperfusion. The development of brain edema was prevented by the administration of dexamethasone or trapidil, but not by indomethacin and OKY-046. Administration of trapidil or dexamethasone was found to prevent the decrease in ATP and the increase of lactic acid. In the indomethacin administrated group, only the increase of lactic acid was prevented. 6-keto-PGF1 alpha was high in the trapidil administrated group and low in the indomethacin administrated group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Involvement of arachidonic acid cascade in brain edema and cerebral energy metabolism after reperfusion]. 359 3

The performance of isolated working rabbit hearts perfused with Krebs-Henseleit (KH) buffer was compared with those in which the buffer was supplemented with washed human red blood cells (KH + RBC) at a hematocrit of 15 percent. When perfused with KH alone at 70 cm H2O afterload and paced at 240 beats/minute, coronary flow was more than double, whereas aortic flow was 40-60 percent of that in hearts perfused with KH + RBC, regardless of left atrial filling pressures (LAFP). Peak systolic pressure reached a plateau at 120 mm Hg in KH + RBC, but at 95 mm Hg in the KH group. Stroke work, however, was similar in the two groups. Despite the high coronary flow, oxygen uptake by hearts perfused with KH was substantially less and did not respond to increases in LAFP as in those perfused with KH + RBC. There was a 20 percent drop in ATP and glycogen content after 90 minutes' perfusion. In contrast, isolated hearts perfused with RBC-enriched buffer remained stable for at least 150 minutes. Irrespective of the perfusate, triacylglycerol content of the muscle remained at similar levels throughout the course of study. Increasing RBC in the perfusate from 15 percent to 25 percent had no additional effect on cardiac performance or oxygen consumption. Our findings demonstrate that in the isolated working rabbit heart inclusion of RBC in the perfusate improves mechanical and metabolic stability by providing an adequate oxygen supply.
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PMID:An improved isolated working rabbit heart preparation using red cell enhanced perfusate. 360 87

The intracellular Na+ content of washed erythrocytes from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto normotensive rats (WKY) was measured by a high resolution 23Na-nuclear magnetic resonance (NMR) technique using a non-permeant aqueous shift reagent, dysprosium triethylenetetramine hexaacetic acid, Dy(TTHA)3-. The initial intracellular Na+ of freshly isolated and washed erythrocytes was very low (approximately 5 mmol/l) and increased progressively with prolonged incubation in isotonic salt solution at 37 degrees C. There was no significant difference in the erythrocyte Na+ concentration between SHRSP and WKY over the entire period of measurement, nor was any difference detected in their osmotic fragility or total cellular volume, although the osmotic fragility decreased with incubation time. The high energy phosphate metabolites were also studied in the same erythrocytes by 31P-NMR. The level of intracellular ATP decreased with incubation at 37 degrees C but showed no difference between the SHRSP and WKY samples. Inclusion of 1 mmol/l ouabain in the incubation medium substantially retarded the breakdown of intracellular ATP and resulted in a concomitant increase in intracellular Na+. However, neither the ouabain-sensitive nor the ouabain-insensitive component of Na+ influx altered in SHRSP erythrocytes compared with WKY erythrocytes in paired experiments. Our results do not support the hypothesis that altered Na+ transport, resulting in an increase in erythrocyte Na+ concentration, is associated with spontaneous hypertension.
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PMID:High resolution 23Na-nuclear magnetic resonance study of stroke-prone spontaneously hypertensive rat erythrocytes. 361 83

In the work by Yanagida et al. (1985) the distance was measured by which the myosin cross-bridge moved along the actin filament during one cycle of ATP hydrolysis. This distance, in the opinion of the authors, must be equal to the length of the cross-bridge power stroke. However the measured distance (60 divided by 68 nm) was considerably greater than the cross-bridge power stroke measured earlier by other methods. In the present paper it is shown on the basis of the kinetic theory of muscle contraction of V. I. Deshcherevsky that the distance, the cross-bridge passed during one cycle of ATP hydrolysis must be nearly 5 times greater than the cross-bridge power stroke. The estimation of the length of the cross-bridge power stroke from the Yanagida's et al. data on the basis of the kinetic model gives 12 divided by 14 nm which is in a good accordance with the results obtained earlier.
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PMID:[Estimating the length of actomyosin cross-bridge contraction]. 362 May 27

Continuous retrograde coronary sinus cardioplegia (CSCP) has previously been carefully evaluated experimentally and shown to be efficacious during ischemia, even in the presence of coronary lesions and in the hypertrophied state. A new technique of retrograde cardioplegia delivery through the right atrium, using right ventricular distension and pressures of 60 mm Hg, has recently been described with excellent clinical results. This study was designed to specifically examine right ventricular function after atrial cardioplegia and acute passive right ventricular distension. CSCP (n = 10) was compared with cardioplegia delivered through the right atrium both continuously (n = 10) and intermittently (n = 8). When ventricular function was examined with the use of the load-independent relationship of stroke work vs end-diastolic length, there was a profound deterioration of right ventricular function in both atrial cardioplegia groups (44% and 37% of control values, respectively) after 1 hr of reperfusion. In contrast, biventricular function was fully preserved in the CSCP group 1 hr after reperfusion. Left ventricular function measured at the end of reperfusion was preserved in all three groups. Right ventricular ATP levels were slightly but significantly depressed in all groups and in the atrial cardioplegia groups, this metabolic change was also seen in the left ventricle. These metabolic and hemodynamic data may reflect the inability of atrial cardioplegia to cool the myocardium below 16 degrees C. Postoperative right ventricular dysfunction may be more common than has been previously thought when atrial cardioplegia is used, particularly in the absence of topical cooling.
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PMID:Ventricular function after atrial cardioplegia. 366 10

The present study examines the effects of resuscitation fluid composition on myocardial function, myocardial high-energy phosphate content, and survival following third-degree anesthetic burn to 35-40% body surface area in the guinea pig. Treatment regimens used were 1) no resuscitation, 2) isotonic saline, 3) Ringer's lactate and 4) Ringer's acetate. Fluids were administered at the rate of 0.334 ml/kg/hr/% burn for 4 hr following injury, at which time myocardial function was assessed. Nonburned animals served as controls. In isolated working hearts, significant depression of myocardial function was observed in nonresuscitated and saline-resuscitated animals as evidenced by decreased cardiac output, dP/dt, -dP/dt, and stroke work. Lactate resuscitation produced some improvement in these parameters but did not restore them to those of nonburned control animals. In contrast, Ringer's acetate resuscitation resulted in normal cardiac output and contractility. Myocardial ATP content of hearts obtained from the various resuscitation groups did not differ from that of nonburned control hearts, except for hearts from Ringer's lactate group, which were significantly lower in myocardial ATP than those of the other groups. No differences were found in creatine phosphate content. Resuscitation with the different fluid regimens for 48 hr produced significant differences in survival. Fluids were given at the rate of 4 ml/kg/% burn for 24 hr. Half of the fluid was given in the first 8 hr and the rest during the remaining 16 hr. Nonresuscitated and saline-resuscitated animals showed significant mortality by 24 hr, whereas lactate- and acetate-treated animals had survival rates of 100% and 87.5%, respectively. However, by 48 hr, only acetate-treated animals survived. These data indicate that important differences exist in the effectiveness of different resuscitation fluids and that Ringer's lactate, the fluid most often utilized clinically, may not provide optimum benefit. In light of these results, serious consideration should be given to the substitution of acetate for lactate during the resuscitation of burn shock patients.
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PMID:Resuscitation fluid composition and myocardial performance during burn shock. 369 Aug 12

Whether the calcium entry blocker, nimodipine, prevents the increase in the concentration of free fatty acids and metabolic disturbances during ischemia and promotes functional and metabolic recovery after recirculation were examined. Severe forebrain ischemia in rats was induced by four-vessel occlusion with mild hypotension. After 30 minutes of ischemia, recirculation was started by removal of the arterial clamps and by increasing blood pressure to the preischemic level. Recovery of EEG activity following recirculation was better in the nimodipine-treated group than in the control group. During the ischemic period, there were no significant differences in accumulation of free fatty acids or in depletion of ATP between treated and control groups. At 120 minutes following recirculation, recovery of the ATP level was significantly better in the treated group than in the control group. Therefore, the promotion of functional and metabolic recovery by nimodipine-treatment is suggested to be not due to the prevention of an accumulation of free fatty acids nor to the depletion of ATP during the ischemic period, but to either improvement of postischemic hypoperfusion or a direct action on metabolic processes during reperfusion period.
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PMID:Effect of nimodipine on cerebral functional and metabolic recovery following ischemia in the rat brain. 371 51

Dichloroacetate (DCA) is known to prevent the phosphorylation of the pyruvate dehydrogenase complex (PDHC) by blocking the action of PDH kinase. This action allows the active PDHC to exert its effect on the metabolism of glucose, lactate and alanine to acetyl CoA. DCA has been shown to reduce serum lactate levels in humans and animals in such conditions as diabetes, phenformin-induced hepatic failure, exercise, and endotoxin-induced shock. Lactic acidosis in the brain has often been postulated as a cause of neuronal damage following ischemia and hypoxia. Therefore, we examined the effect of intravenously administered DCA (100 mg/kg) in rats that were rendered hyperglycemic by intravenous glucose (2 g/kg), and then made to undergo 15 minutes of incomplete cerebral ischemia by bilateral carotid ligation and systemic hypotension (mean arterial pressure of 50 mm Hg). DCA significantly reduced serum lactate levels pre-ischemia, but had no effect on serum lactate levels after ischemia induction. Brain levels of lactate, ATP and PCr after 15 minutes of incomplete ischemia were unaffected by DCA. We conclude that in this in-vivo model the control of PDHC activity in the brain may be different than that in the periphery, and that DCA was not effective in reducing brain tissue lactate levels.
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PMID:The effect of dichloroacetate on brain lactate levels following incomplete ischemia in the hyperglycemic rat. 371 55

The efficacy of blood and crystalloid retrograde cardioplegia in protecting the ischemic myocardium was compared. Seventeen dogs underwent 2 hr of global myocardial ischemia while on cardiopulmonary bypass. Crystalloid (in nine dogs) or blood (in eight dogs) cardioplegic solution was infused continuously into the coronary sinus. Left and right ventricular function were assessed before ischemia and after 30 and 60 min of reperfusion by means of highly sensitive, load-independent index of contractility (the slope of the stroke work vs end-diastolic length relationship). Ventricular biopsies for ATP determination were obtained before ischemia, at the end of ischemia, and after 60 min of reperfusion. Left and right ventricular function returned to normal after 60 min of reperfusion in both groups. Left ventricular ATP remained unchanged, whereas small but significant decreases in right ventricular ATP were observed after 60 min of reperfusion in both groups. Thus continuous crystalloid or blood retrograde coronary sinus cardioplegia in dogs preserved myocardial function and metabolism equally well after 2 hr of global cardiac ischemia.
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PMID:The efficacy of blood versus crystalloid coronary sinus cardioplegia during global myocardial ischemia. 376 91

In normothermic cats, cerebral blood flow was arrested for 1 hour followed by blood recirculation for 5-6 hours. Functional recovery was evaluated by qualitative and quantitative EEG analysis, and metabolic recovery by measuring metabolite and electrolyte levels in tissue samples taken from the cerebral cortex. In 5 out of 12 animals EEG activity did not recover after ischemia (group I); in 3 animals, intermittent EEG activity (group II) and in 4 animals continuous EEG activity returned during the observation period (group III). In group I the energy state was severely disturbed and an increase of calcium was detected, in group II this disturbance was much less pronounced, and in group III changes in energy metabolism and ion concentration were absent with the only exception of lower ADP levels. During recovery, the total intensity of EEG correlated positively with ATP (p less than 0.01) and inversely with lactate (p less than 0.05), and the intensity of the delta band inversely with sodium content (p less than 0.05). The results obtained demonstrate that electrophysiological recovery after prolonged ischemia is closely correlated with the restoration of the energy state and of electrolyte homeostasis of the brain. The inverse relationship of EEG intensity with lactate and sodium are interpreted as evidence for the adverse effects of ongoing post-ischemic glycolysis, resulting in the activation of the H+/Na+ antiporter for the regulation of intracellular pH.
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PMID:Relationship between metabolic recovery and the EEG prolonged ischemia of cat brain. 381 Jul 16


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