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

Ligature and section of the abdominal aorta results in only minor and temporary functional and metabolic changes in the slow soleus muscle of the rat. A very small decrease in maximal tetanic tension corresponds to a few scattered areas of damaged and necrotic muscle fibres, in which decreased succinic dehydrogenase and loss of phosphorylase activity was observed. A new experimental approach, i.e. ligature and section of the abdominal aorta combined with terminal devascularisation, preserving intact tendons and innervation of the muscle causes maximal muscle ischemia, followed by an almost complete loss of tetanic tension output, marked shortening of contraction time and profound morphological and histochemical changes. The decrease in succinic dehydrogenase and ATPase activities and loss of phosphorylase activity occur in the majority of degenerating muscle fibres except for a thin rim of peripheral fibres during the first 4 days. Subsequently, the contractile properties recover gradually and enzyme activities reappear in the regenerating muscle fibres simultaneously with new revascularisation. Thirty days after the operation all the parameters observed returned to control values.
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PMID:Effect of ischemia on contractile and histochemical properties of the rat soleus muscle. 15 45

The evolution of experimental myocardial infarction in the Rat with or without revascularization has been studied histochemically and histoenzymatically in 56 animals sacrified after 1, 6, 12, 24, 48 hrs and 7 days. Following permanent ischemis (14 animals), there appeared an extended transversal infarction marked by the complete disappearance of all phosphorylase activity (P-ase) after the first hour. During the first 6 hrs, changes appeared in succinodeshydrogenase (SHD) and cytochrome oxydase (Cyt-Ox). Glucose-6-phosphodeshydrogenase (G6PDH) presisted until lysis of the necrotic focus. It was possible to define a perinecrotic marginal area in which Pase activity is absent and SDH is granular "G3 in nature, characterized by continuous remodeling in the first 48 hrs. Following temporary ischemia (42 animals) the evolution was marked by rapid tissue reactions and early regression of the marginal zones. After 48 hrs and 7 days of survival, the planimetric evaluation of the infarcted area shows a definite reduction in the size of the infarctus in 50% of cases following removal of the ligature after 6 hrs, and in 66% of cases following removal of the ligature after 1 hr. It would appear probable that the revitalization of certain myocardial areas may extend from the marginal zones as is suggested by the reappearance in these zones several hrs after revascularization of P-ase and SDH activity. On the other hand, it is also true that the early restoration of blood flow does not always prevent the occurrence of an extended infarction. Certain recent observations have shown microcirculatory changes which are secondary to anoxia and should be studied further.
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PMID:[Histochemical and histoenzymatic study of experimental myocardial infarction in the rat by temporary and permanent ligation of the left coronary artery (author's transl)]. 16 14

The activity of adenylate cyclase and the steady state levels of cyclic AMP (cAMP) were determined in stria vascularis (SV) and organ of Corti (OC) of the guinea pig cochlea. The activities are 12 and 19 pmoles/mg dry weight/minute for OC and SV, respectively. The activity was increased two to four-fold by NaF. The base level of cAMP is 4.2 and 4.4 nmoles/g dry weight in OC and SV, respectively. In contrast to brain, neither ischemia nor barbiturates produced major changes of the steady state levels of cAMP. No in vitro effect of cAMP upon the state of activation of glycogen phosphorylase was noticeable in either tissue. cAMP did not exert a significant in vitro inhibition of strial Na+K+-ATPase. Perilymphatic perfusion of cAMP (10-3 M) and of theophylline (5 times 10-3 M) did not produce changes in the endolymphatic potential (EP), but dibutyryl cAMP (10-3 M) led to a significant increase of EP. The alpha adrenergic blocking agent, phentolamine, produced very complex changes of the cochlear potentials. A possible role of catecholamines and cAMP in the secretory phenomena of the SV and in the transduction and/or transmission processes of the auditory sense organ are discussed.
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PMID:Cyclic AMP and adenylate cyclase in the inner ear. 16 45

The histochemical and ultrastructural effects of extracorporeal circulation and aortic cross-clamping during coronary heart surgery have been examined in drill biopsy samples of the left ventricle in 22 patients. The biopsies were obtained before and after bypass with a DeSoutter drill. Histochemical studies indicated definite differences between control and experimental biopsies, with increased succinic dehydrogenase, cytochrome oxidase, and LDH activity, while phosphorylase A and myosin ATPase activities declined. Furthermore, free phospholipid levels increased, as determined by the acid hematein reaction. Ultrastructural examination demonstrated loss of glycogen, intracellular swelling, and mitochondrial damage, which included loss of matrix density, loss of cristae, and eventual disruption in the postbypass biopsy. These results, which closely resemble the effects of ischemia and reperfusion observed in animal experiments, suggest that the initial insult is a change in membrane permeability regulation.
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PMID:Histochemical and structural changes in human myocardial cells after cardiopulmonary bypass. 16 88

The article deals with oxidation of different substrates, intensity of glycolytic and glycogenolytic processes in mitochondria and homogenates of dog liver with its 2-hour exclusion from circulation under conditions of endotracheal ether-oxygen narcosis. It was established that already 30-60-minute ischemia causes a decrease in intensity of succinate, alpha-ketoglutarate oxidation and acceptor respiration, inhibiton in the activity of the citrate cycle enzymes; succinate dehydrogenase, alpha-ketoglutarate dehydrogenase, isocytrate dehydrogenase. The activity of NAD-dependent malate dehydrogenasedehydrogenase and Mg2+-ATPase as well as intensity of NADN oxidation in mitochondria increase. After 2-hour ischemia the activity of Mg2+-ATPase, cytochrome oxidase and peroxidase lowers. A sharply developed glycogenolysis is accompanied by inhibition of phosphorylase activity and a two-fold stimulation of the glycolytic reactions. Peculiarities in regulation of enzymatic reactions under conditions of ischemia and their role in origin of metabolism disturbances in the liver are under discussion.
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PMID:[Carbohydrate metabolism in the liver in acute ischemia]. 17 60

The ischemic effect on cerebral enzymes and glycogen content was histochemically evaluated in mongolian gerbils subjected to unilateral common carotid artery occlusion for various periods of time from 1/2 to 9 h. In early stages (up to 2 h), the only enzyme affected was the phosphorylase which revealed a decreased activity. Thereafter, the observed changes inclusive of glycogen and other enzymes such as the dehydrogenase, nonspecific acid and alkaline phosphatases, leucine aminopeptidase and thiamine pyrophosphatase progressed proportionally to the duration of ischemia. There was an overall inverse appearance of histochemically demonstrated enzymatic disturbances between the severely damaged ischemic regions and its marginal zones; the former revealing a conspicuous decrease and/or loss of enzymatic activities while the latter showing an increase of the same enzymes. Correlating the various ischemic responses of the intracellular organelles it appears that the changes in the lysosomes and Golgi apparatus occurred slower than those of mitochondria.
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PMID:Histochemical investigation of the Mongolian gerbil's brain during unilateral ischemia. 45 53

The effect of pretreatment with ouabain (40 microgram/kg, i.v.) on myocardial metabolic and contractile responses to regional ischemia induced by coronary artery ligation was studied in the canine left ventricle. In control dogs, ischemia increased activity of phosphorylase a and the levels of glucose-6-phosphate and lactate, and decreased the levels of glycogen and phosphocreatine, without affecting the levels of adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate (AMP). Ouabain increased the activity of phosphorylase a. In ouabain-treated dogs, ischemia did not further increase the phosphorylase a activity but it increased the epicardial AMP level. Other metabolic responses to ischemia in ouabain-treated dogs were similar to those in control dogs. In control dogs, myocardial contractile force decreased by about 10% after ischemia, but blood pressure and heart rate remained unchanged. Ouabain increased contractile force by about 32%. In ouabain-treated dogs, ischemia decreased contractile force by about 54% without affecting blood pressure and heart rate. It is concluded that ouabain increases the activity of the myocardial phosphorylase a and that the inotropic action of ouabain can be nullified by coronary artery ligation.
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PMID:Effect of ouabain on myocardial metabolic and contractile responses to coronary ligation. 61 33

The authors examined the effects of reperfusion after temporary ischemia in 50 dogs. The morphologic alterations were documented by methods of electron microscopy, fluorescence microscopy, and histochemistry. Lactate and activity of glycogen phosphorylase were assessed. According to the results, the optimal ischemia interval is 30 to 60 minutes for rational application of reperfusion, while it is just possible after 120 minutes. After a 4-hours-period of ischemia reperfusion increase morphologic damage of myocardium and impairment of myocardial metabolism. Prolonged reperfusion of 7 days resulted in a reduced extent of infarction compared with controls. In non-ischemic myocardium the morphologic and metabolic alterations were less expressed. The effects of "no-reflow"-phenomenon and conclusions for clinical practice are discussed.
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PMID:[Experimental studies on surgical therapy of acute infarct]. 65 78

The effect of the reperfusion on myocardial infarction has been studied in the rat in order to assess the possible reversibility of myocardial damage. The present study deals with reperfusion of experimental myocardial infarction in the rat. Two groups of animals were compared: one was subjected to permanent ischemia and the other was subjected to ischemia of variable duration 1) hour to 24 hours). The differences between infarction caused by permanent ischemia and the evolution of infarction following reperfusion were studied by means of histologic (121 specimens) histoenzymatic (56 specimens), ECG (100 specimens), techniques and study of the mcirocirculation (70 specimens). The size of the infarctions caused by temporary ischemia was found to be significantly smaller in 60% of the cases as compared to the infarctions caused by permanent ischemia. Histoenzymatic study (phosphorylase activity and succinodehydrogenase activity) confirmed the existance of a marginal zone extending over one third of the surface of the ischemic myocardium: reperfusion permitted the salvage of this zone and thereby diminished the extent of necrosis. The latter findings were further confirmed by the ECG study showing earlier regression of ischemic ST changes following early reperfusion. Microcirculatory changes secondary to anoxia may account for the fact that, in a certain percentage of the cases, early reperfusion does not prevent extension of infarction.
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PMID:The effect of coronary artery reperfusion on the extent of myocardial infarction. 84 30

Histologic investigations together with histochemical and photometric measurements of enzyme activities were performed in retina of rabbits, whose blood supply had been totally interrupted for 1h. A retinal edema developed affecting the internal layers between the inner limiting membrane and the internal plexiform and ganglion cell layer. Although this edema was quite remarkable at the posterior pole of the eye, it diminished toward the periphery, disappearing near the ora serrata. The activities of the following enzymes were investigated: hexokinase, glucose 6-phosphate dehydrogenase, aldolase, glyceraldehydephosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, succinate dehydrogenase, ATPase, and phosphorylase. The most striking finding was the total disappearance of phosphorylase activity under pressure ischemia. ATPase and aldolase showed a decreased activity in the ischemic retina, and malate dehydrogenase a slightly diminished one. Concerning the other enzymes, no significant differences between normal and ischemic retina were observed.
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PMID:Enzymologic and histologic investigations in normal and pressure-ischemic retina of rabbits. 108 79


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