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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in vitro preparation of the chick retina can be used to show the occurrence of transient changes in the intracellular pH and of energy metabolites which occurs during spreading depression (SD). There is an initial increase in intracellular pH associated with elevated values for ADP, P-Creatine, lactate and pyruvate, an intermediary acid shift with increases in ATP values and decreases in ADP, and a late alkaline rebound where P-Creatine levels are reduced and the content of ADP and lactate are elevated. These transient changes in intracellular pH observed during SD, when correlated to the levels of energy metabolites, supports the hypothesis that the intracellular pH can be used by the tissue as a mechanism to rapidly modify the metabolic activities of neurons and glial cells. We suggest that the first alkaline shift is caused by glial cells and the intermediary acid shift by neurons. However, a specific cell could not be pointed out as responsible for the late alkaline shift but it could explain the refractoriness of the neurons during the phenomenon.
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PMID:Transient changes in energy metabolites and intracellular pH during spreading depression in the chick retina. 174 66

The influence of hypothyroidism on the transport of phosphate and on the lipid composition in rat-liver mitochondria was examined. It was found that the rate of phosphate transport is reduced (around 40%) in mitochondria from hypothyroid rats compared to that obtained in mitochondria from normal rats. Treatment of hypothyroid rats with thyroid hormone reverses this effect completely. Kinetic analysis of the phosphate transport indicates that only the Vmax of this process is affected, while there is no change in the Km values. The lower rate of phosphate transport in mitochondria from hypothyroid rats is also demonstrated by swelling experiments. There is no significant difference either in the respiratory control ratios or in the ADP/O ratios between these two types of mitochondria. The hepatic mitochondrial lipid composition is altered significantly in hypothyroid rats. The total cholesterol increases, the phospholipids decrease and the cholesterol/phospholipid molar ratio increases (around 40%). Among the phospholipids, cardiolipin shows the greatest alteration (30% decrease in the hypothyroid rats). The phosphatidylethanolamine/phosphatidylcholine ratio also decreases. Alterations were also found in the pattern of fatty acids. These changes in lipid composition may be responsible, at least in part, for the depression of the phosphate carrier activity in mitochondria from hypothyroid rats.
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PMID:The influence of hypothyroidism on the transport of phosphate and on the lipid composition in rat-liver mitochondria. 175 24

The effects of the intravenous administration of 100 mg of trapidil on systolic and diastolic left ventricular functions and coronary sinus blood flow, as well as on myocardial lactate metabolism and platelet aggregation, were investigated before and after pacing in 12 patients with coronary artery disease. Pacing without administration of trapidil provoked angina in 6 of these patients. During rest, trapidil decreased the mean blood pressure by an average of 5 mmHg (from 112 +/- 15 to 107 +/- 8 mmHg, p less than 0.05) and the left ventricular end-diastolic pressure by an average of 4 mmHg (from 10 +/- 3 to 6 +/- 2 mmHg, p less than 0.05). Trapidil also caused both the max dp/dt and the coronary sinus blood flow to increase slightly, although it had no significant effect on diastolic function, myocardial lactate metabolism, or platelet aggregation. During the pacing that followed trapidil administration, chest pain was not provoked in the same 6 patients who had previously experienced chest pain on pacing. The extent of ST-segment depression also improved from -1.6 +/- 0.3 to -0.9 +/- 0.7 mm (p less than 0.05) and there was a significant suppression of the production of myocardial lactate. When pacing was terminated, trapidil caused a decrease in left ventricular systolic pressure from 173 to 156 mmHg (p less than 0.05), and also caused a decrease of the left ventricular end-diastolic pressure, from 16 +/- 4 to 8 +/- 2 mmHg (p less than 0.05). Trapidil had no significant effect on platelet aggregation activity with either a 1 microM or a 2 microM dose of ADP (adenosine diphosphate). However, the beta-TG level was suppressed, decreasing from 119 +/- 14 to 99 +/- 19 ng/ml in the arterial blood (p less than 0.1) and from 114 +/- 9 to 103 +/- 17 ng/ml (p less than 0.1) in the coronary sinus blood. Reductions in the preload and afterload by trapidil were of far greater magnitude than either its coronary dilatory or positive chronotropic effects in patients with coronary artery disease. Thus trapidil, a new antianginal agent appears to inhibit the production of platelet derived growth factors and may, therefore, protect the arteries from atherosclerosis as it promotes beneficial systemic hemodynamics in patients with depressed ventricular function.
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PMID:The effects of trapidil on left ventricular function and platelet aggregation in patients with coronary artery disease subjected to pacing. 183 67

The effect of dipyridamole (DYP) on postischemic myocardial function and metabolism was studied using the isolated rabbit heart model. Twenty-one isolated rabbit heart preparations were divided into two groups: KH (control N = 10) were reperfused after 24 min normothermic hyperkalemic arrest with modified Krebs-Henseleit buffer (KH) while DYP (N = 11) were reperfused with KH and 5 X 10(-6) M DYP. Hearts were analyzed for myocardial function (DP, developed pressure, +dp/dt, -dp/dt) and metabolic function (ATP, CrP, ADP, AMP, purines, and lactate levels). Data analysis revealed significant reperfusion depression in DYP myocardial function compared with KH (P less than 0.05): DP (42 +/- 6 vs 89 +/- 7 mm Hg), +dp/dt (390 +/- 21.6 vs 1227 +/- 48.4), and -dp/dt (280 +/- 20.1 vs 677 +/- 19.8). Comparison of DYP to KH metabolic parameters was also significantly different (P less than 0.05): ATP (5.8 +/- 0.7 vs 9.5 +/- 1.4), ADP (2.1 +/- 0.2 vs 3.2 +/- 0.6), CrP (9.6 +/- 0.3 vs 17.2 +/- 1.3). Tissue purines (adenosine and inosine) were significantly elevated (P less than 0.01) in the DYP group, while coronary sinus purines and lactate loss were similar. Thus, the data suggest that DYP, present during postischemic reperfusion, depresses myocardial function by inhibiting adenosine phosphorylation, thereby decreasing the generation of high-energy phosphates without increased substrate loss or ischemia.
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PMID:Metabolic and functional cardiac impairment after reperfusion with persantine. 186 75

The effect of severe insulin-induced hypoglycemia on the activity of the pyruvate dehydrogenase enzyme complex (PDHC) was investigated in homogenates of frozen rat cerebral cortex during burst suppression EEG, after 10, 30, and 60 min of isoelectric EEG, and after 30 and 180 min and 24 h of recovery following 30 min of hypoglycemic coma. Changes in PDHC activity were correlated to levels of labile organic phosphates and glycolytic metabolites. In cortex from control animals, the rate of [1-14C]pyruvate decarboxylation was 7.1 +/- 1.3 U/mg of protein, or 35% of the total PDHC activity. The activity was unchanged during burst suppression EEG whereas the active fraction increased to 81-87% during hypoglycemic coma. Thirty minutes after glucose-induced recovery, the PDHC activity had decreased by 33% compared to control levels, and remained significantly depressed after 3 h of recovery. This decrease in activity was not due to a decrease in the total PDHC activity. At 24 h of recovery, PDHC activity had returned to control levels. We conclude that the activation of PDHC during hypoglycemic coma is probably the result of an increased PDH phosphatase activity following depolarization and calcium influx, and allosteric inhibition of PDH kinase due to increased ADP/ATP ratio. The depression of PDHC activity following hypoglycemic coma is probably due to an increased phosphorylation of the enzyme, as a consequence of an imbalance between PDH phosphatase and kinase activities. Since some reduction of the ATP/ADP ratio persisted and since the lactate/pyruvate ratio had normalized by 3 h of recovery, the depression of PDHC most likely reflects a decrease in PDH phosphatase activity, probably due to a decrease in intramitochondrial Ca2+.
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PMID:Changes in pyruvate dehydrogenase complex activity during and following severe insulin-induced hypoglycemia. 198 96

A study was made of the blood and tissue oxygen regime in patients with vibratory disease (VD) induced by local vibration and of the importance of lipid peroxidation (LPO) in oxygenation disorders. Venous hyperoxia, a decrease of the arteriovenous difference according to oxygen, the percentage of oxygen utilization by tissues, shift of the acid-base balance towards metabolic acidosis were established, attesting to tissue hypoxia that increased with the gravity of VD. The importance of a steady activation of LPO and depression of the antioxidant system in the pathogenesis of hypoxia associated with VD was supported by the correlation analysis data on oxygen balance and LPO, the functional and metabolic characteristics of red blood cells (according to the viscosity of red blood cell suspension and the content in the cells of SH-groups, lipoproteins and histidine) and platelets (according to aggregation in response to ADP and thrombin) as well as by the level of blood serum fluorescence. The authors provide evidence for the use of antioxidants (a complex of alpha-tocopherol with ascorbic acid and methionine and calcium antagonists of the nifedipine group), giving a membranostabilizing effect, in multimodality treatment of patients afflicted with VD.
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PMID:[Cell-membrane aspects of the pathogenesis of hypoxia in vibration disease induced by local vibration]. 204 32

Isolated rat liver mitochondria have been incubated in the presence of the general anesthetic 2,6-diisopropylphenol (0-100 microM) and the efficiency of oxidative phosphorylation has been evaluated by measuring the respiratory rates, the rates of ATP synthesis or hydrolysis and the magnitude of the transmembrane electrical potential. The results obtained indicate that: (a) in mitochondria energized either by succinate or by ATP, 2,6-diisopropylphenol decreased the transmembrane electrical potential and increased the rates of either electron transfer or ATP hydrolysis; (b) in succinate-energized mitochondria 2,6-diisopropylphenol, at concentrations causing substantial depression of the transmembrane electrical potential, did not modify either the rate of phosphorylation of added ADP or the rate of ADP-stimulated respiration: (c) in succinate-energized mitochondria 2,6-diisopropylphenol caused a concentration-dependent inhibition of the uncoupler-stimulated rate of succinate oxidation. These findings suggest that under the experimental conditions reported 2,6-diisopropylphenol affected the generation and/or maintenance of the transmembrane electrical potential while leaving unchanged the coupling between the electron flow in the respiratory chain and the synthesis of ATP.
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PMID:Influence of the anesthetic 2,6-diisopropylphenol on the oxidative phosphorylation of isolated rat liver mitochondria. 206

The present study aimed to study the relation between the release of arachidonic acid (AA) and the energy state in cerebral cortices of rats during single episodes of cortical spreading depression (CSD). The changes in concentrations of AA, labile phosphate compounds [ATP, ADP, AMP, and phosphocreatine (PCr)], and glycolytic metabolites (lactate, pyruvate, glucose, and glycogen) were studied during and following the large change of the local direct current (DC) potential. Free AA increased markedly during the DC shift, continued to increase during the subsequent 3 min, and returned to control levels at 4-5 min after CSD. PCr decreased by 38% in the first minutes following the DC shift, while ADP increased by 38%. Both returned to normal within a few minutes. ATP, AMP, and energy charge remained constant throughout the experimental period. Glucose decreased by 47% and glycogen by 34% for a few minutes following CSD, while lactate increased by 105% at 2-3 min and by 77% at 4-5 min after CSD. The metabolites returned to control levels at 10 min after CSD. Considering the constant energy charge at all time points during CSD, it is suggested that the AA rise reflects augmented phospholipase activity due to either increased intracellular [Ca2+] or receptor stimulation or both. The possibility that N-methyl-D-aspartate receptors play a role in the release of AA, and that free AA in turn could be part of the mechanism of CSD, is discussed.
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PMID:Cortical spreading depression is associated with arachidonic acid accumulation and preservation of energy charge. 210 27

The effects of ketotifen (Ket) on rabbit platelet aggregation induced by platelet activating factor (PAF), ADP and arachidonic acid (AA) and PAF formation from A-23187-stimulated rat neutrophils in vitro were studied. PAF (15-100 pmol/L) induced rabbit platelet aggregations, with an EC50 of 33 pmol/L. Ket shifted the PAF dose-dependent platelet aggregation curve to the right in a parallel fashion with no depression of the maximal response and reversed the secondary aggregation phase, suggesting that Ket had competitive antagonistic activity against PAF-induced platelet aggregation. It also showed inhibitory effects on platelet aggregations induced by ADP 10 mumol/L and AA 50 mumol/L, the IC50 were 94.5 and 143.5 mumol/L respectively. However, it failed to influence PAF formation from rat neutrophils stimulated by A-23187 2.5 mumol/L in vitro. The inhibitory effects of Ket on platelet activation, particularly PAF-induced platelet aggregation, may contribute to its anti-asthmatic properties.
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PMID:[Effects of ketotifen on rabbit platelet aggregation and platelet activating factor formation from rat neutrophils]. 213 Jun 17

Reperfusion of rabbit hearts after 15 min of global ischemia at 37 degrees C depressed developed pressure by 36% (myocardial stunning). Changes in myofilament function were investigated as causes of this depression. Kinetic analysis of the effects of stunning on myofibrillar catalyzed ATP hydrolysis showed that stunning lowered Michaelis constant (Km) slightly and left maximal enzyme reaction velocity unaltered in the stunned myofilaments. The myofilament end of the creatine kinase (CK) shuttle was also found to be unaffected in the stunned myofibrils. The Km ADP for myofibrillar CK from control and stunned hearts was 60.45 +/- 3.45 and 68.04 +/- 2.42 microM, respectively, and the CK activity at 100 microM ADP was 0.63 +/- 0.08 and 0.67 +/- 0.04 IU/mg myofibrillar protein from control and stunned hearts, a rate three times greater than the myofibrillar adenosinetriphosphatase (ATPase) rate and a rate sufficient to deliver ATP to the myofilaments. Myofilament Ca2+ sensitivity was assessed by measuring Ca2(+)-dependent myofibrillar Mg2(+)-ATPase activity at free [Ca2+] ranging from 10 nM to 32 microM and [Mg.ATP] of 0.8, 1.6, and 3.2 mM. The sensitivity of myofilaments to activation by Ca2+ was unaltered in the myofibrils isolated from stunned hearts. It is concluded from these analyses that the depression of pressure development observed in stunned hearts is not due to a defect in myofilament function.
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PMID:Effect of global myocardial stunning on Ca2(+)-sensitive myofibrillar ATPase activity and creatine kinase kinetics. 214 2


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