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ABSTRACT: Plantlets of Pfaffia glomerata (Spreng.) were exposed in vitro for 30 days to five lead levels (0-400 μM) to analyze the effects on growth and oxidative stress and responses of various antioxidants vis-à-vis lead accumulation. The plantlets showed significant lead accumulation in roots (1,532 μg g(-1) DW) with a low root to shoot lead translocation (ca. 3.6%). The growth of plantlets was negatively affected by various lead treatments, although the level of photosynthetic pigments did not alter significantly in response to any lead treatment. However, plantlets suffered from oxidative stress as suggested by the significant increase in malondialdehyde levels in root (8.48 μmol g(-1) FW) and shoot (3.20 μmol g(-1) FW) tissues with increasing lead treatments. In response to the imposed toxicity, increases in the activities of catalase in root (4.14 ∆E min(-1) mg(-1) protein) and shoot (3.46 ∆E min(-1) mg(-1) protein) and superoxide dismutase in root (345.32 units mg(-1) protein) and shoot (75.26 units mg(-1) protein), respectively, were observed, while the levels of non-protein thiols and ascorbic acid were not affected significantly in either roots or shoots.
Bulletin of Environmental Contamination and Toxicology 02/2011; 86(3):272-7. · 1.02 Impact Factor
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V C Pimentel,
F V Pinheiro,
K S De Bona,
P A Maldonado,
C R da Silva,
S M de Oliveira,
J Ferreira,
C M Bertoncheli, M R Schetinger,
S C A Da Luz,
M B Moretto
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ABSTRACT: Brain damage from neonatal hypoxia-ischemia (HI) plays a major role in neonatal mortality and morbidity. Using the Rice-Vannucci model of HI in rats, we verified that 8 days after HI injury, adenosine deaminase (ADA), N-acetyl-glucosaminidase (NAG) and myeloperoxidase (MPO) activities increased in the left hemisphere hippocampus (HI group); however, the activity of 5'-nucleotidase (5'NT) remained unchanged. In the hematoxylin-eosin analysis (HE), we detected selective and delayed degeneration of hippocampal pyramidal neurons and astroglial reaction accompanied by glial fibrillary acidic protein (GFAP)-positive and vimentin-positive in the immunohistochemistry analysis in the HI group compared with the control group. We observed the selective necrosis of neurons, vascular endothelial proliferation and inflammatory response accompanied by the increase of the key enzyme of adenosine metabolism in the HI group. The increase of ADA activity, despite the 5'NT activity was not altered, indicates the predominance of ADA activity in the postischemic homeostasis of extra cellular adenosine. The presence of leukocytes into the ischemic areas displays the possible importance of the neutrophil-macrophages associated with the increase of MPO and NAG activities 8 days after HI. These findings may contribute to the evaluation of some consequences of the damage caused by neonatal HI.
Brain research 02/2011; 1388:134-40. · 2.46 Impact Factor
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ABSTRACT: Long time ago aluminum (Al) was considered as a non-toxic element and its use had no restrictions. However, over the last two decades, scientific publications have indicated that Al is a toxic element. In line with this, aluminum accumulation in the organism is associated with a variety of human pathologies. Efficient therapeutics approach to treat Al intoxication are still not available, but there is a consensus that chelation therapy is the procedure to be used. However, the development of new chelating agents are highly desirable to improve the efficacy of the treatment of Al intoxication. The present study evaluates the chelating effect of two novel pyrimidines: 4-tricloromethyl-1-H-pyrimidin-2-one (THP) and (4-methyl-6-trifluoromethyl-6-pyrimidin-2-il)-hydrazine (MTPH) in a mice model of aluminum intoxication and compares their efficacy with those of desferrioxamine (DFO), a classical agent used for treat Al accumulation. The animals were exposed to aluminum by gavage (0.1 mmol aluminum/kg/day) 5 days/week for 4 weeks. At the end of this period, DFO was injected i.p. and the novel pyrimidines were given by gavage at 0.2 mmol/kg/day for five consecutive days. Aluminum concentration in tissues (brain, liver, kidney and blood) was determined by graphite furnace atomic absorption spectroscopy (GFAAS). The results showed that when administered by gavage, aluminum accumulated in the brain, kidney and liver of mice. MTPH was able to decrease aluminum levels in aluminum plus citrate animal groups, whereas THP was inefficient for this purpose. However, the novel pyrimidines used in this study were unable to surpass the aluminum chelating property of DFO. Thus, new studies must be performed utilizing other chelating agents which can decrease aluminum toxicity.
Journal of Inorganic Biochemistry 10/2005; 99(9):1853-7. · 3.35 Impact Factor
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ABSTRACT: The inhibition of adenine nucleotide hydrolysis by heparin and chondroitin sulfate (sulfated polysaccharides) was studied in membrane preparations from liver and kidney of adult rats. Hydrolysis was measured by the activity of NTPDase and 5'-nucleotidase. The inhibition of NTPDase by heparin was observed at three different pH values (6.0, 8.0 and 10.0). In liver, the maximal inhibition observed for ATP and ADP hydrolysis was about 80% at pH 8.0 and 70% at pH 6.0 and 10.0. Similarly to the effect observed in liver, heparin caused inhibition of ATP and ADP hydrolysis that reached a maximum of 70% in kidney (pH 8.0). Na(+), K(+) and Rb(+) changed the inhibitory potency of heparin, suggesting that its effects may be related to charge interaction. In addition to heparin, chondroitin sulfate also caused a dose-dependent inhibition in liver and kidney membranes. The maximal inhibition observed for ATP and ADP hydrolysis was about 60 and 50%, respectively. In addition, the hepatic and renal activity of 5'-nucleotidase was inhibited by heparin and chondroitin sulfate, except for kidney membranes where chondroitin sulfate did not alter AMP hydrolysis. On this basis, the findings indicate that glycosaminoglycans have a potential role as inhibitors of adenine nucleotide hydrolysis on the surface of liver and kidney cell membranes in vitro.
The International Journal of Biochemistry & Cell Biology 01/2002; 33(12):1193-201. · 4.63 Impact Factor
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ABSTRACT: Ecto-enzymes capable of hydrolyzing ATP and ADP (NTPDase) are present in the central nervous system of various species. In the present investigation we studied the synaptosomal NTPDase (ATP diphosphohydrolase, apyrase, E.C. 3.6.1.5) from fish, chicken and rats under different conditions and in the presence of several classical inhibitors. The cation concentration required for maximal activity was 0.5 mM for fish, 1.0 mM for chickens and 1.5 mM for rats with both substrates. The results showed that the pH optimum for all animal preparations was close to 8.0. The temperature used was 25-27 degrees C for fish and 35-37 degrees C for chicken and rat preparations. The inhibitors azide and fluoride only inhibited the preparation at high concentrations (10 mM). Lanthanum (0.1-0.4 mM), N-ethylmaleimide (0.4-3.0 mM) and ouabain (0.5-3.0 mM) had no effect on NTPDase activity from fish, chickens or rats. Orthovanadate (0.1-0.3 mM) only inhibited fish synaptosomal NTPDase. Trifluoperazine (0.05-0.2 mM) and suramin (0.03-0.3 mM) inhibited NTPDase at all concentrations tested. Suramin was the most potent compound in causing inhibition, presenting inhibition at 30 microM. Our results demonstrate that the synaptosomal NTPDase response to several factors is similar in fish, chickens and rats, and that the enzyme presents functional homology.
Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology 05/2001; 128(4):731-41. · 1.92 Impact Factor
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ABSTRACT: The effects of transient forebrain ischemia, reperfusion and ischemic preconditioning on rat blood platelet ATP diphosphohydrolase and 5'-nucleotidase activities were evaluated. Adult Wistar rats were submitted to 2 or 10 min of single ischemic episodes, or to 10 min of ischemia 1 day after a 2-min ischemic episode (ischemic preconditioning) by the four-vessel occlusion method. Rats submitted to single ischemic insults were reperfused for 60 min and for 1, 2, 5, 10 and 30 days after ischemia; preconditioned rats were reperfused for 60 min 1 and 2 days after the long ischemic episode. Brain ischemia (2 or 10 min) inhibited ATP and ADP hydrolysis by platelet ATP diphosphohydrolase. On the other hand, AMP hydrolysis by 5'-nucleotidase was increased after 2, but not 10, min of ischemia. Ischemic preconditioning followed by 10 min of ischemia caused activation of both enzymes. Variable periods of reperfusion distinctly affected each experimental group. Enzyme activities returned to control levels in the 2-min group. However, the decrease in ATP diphosphohydrolase activity was maintained up to 30 days of reperfusion after 10-min ischemia. 5'-Nucleotidase activity was decreased 60 min and 1 day following 10-min ischemia; interestingly, enzymatic activity was increased after 2 and 5 days of reperfusion, and returned to control levels after 10 days. Ischemic preconditioning cancelled the effects of 10-min ischemia on the enzymatic activities. These results indicate that brain ischemia and ischemic preconditioning induce peripheral effects on ecto-enzymes from rat platelets involved in nucleotide metabolism. Thus, ATP, ADP and AMP degradation and probably the generation of adenosine in the circulation may be altered, leading to regulation of microthrombus formation since ADP aggregates platelets and adenosine is an inhibitor of platelet aggregation.
Brazilian Journal of Medical and Biological Research 12/2000; 33(11):1369-77. · 1.13 Impact Factor
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ABSTRACT: The objective of this study was to investigate aluminum deposition in whole blood and plasma of mice and the activity of blood delta-aminolevulinic acid dehydratase (ALA-D) after in vitro and in vivo exposure to this element. In vitro experiments showed activation and inhibition of the enzyme activity when 0.01-5.0 mM of aluminum sulphate were used (IC(50): 1.31 mM). Treatment with citrate and aluminum plus citrate increased ALA-D activity in vivo and the increase in enzyme activity was parallel to the increase in aluminum content in blood and plasma. These results show that aluminum has a distinct effect on ALA-D activity: first, at relatively lower concentrations it activated, and at high concentration it inhibited, blood ALA-D in vitro; second, it activated the enzyme when administered to drinking water. One important toxicological finding of the present report is that the apparent irrelevant addition of citrate to the drinking water significantly increased the level of aluminum in blood and plasma. Thus, in order to predict more accurately the extent of human exposure to aluminum it would be advantageous to consider the level of citrate ingestion and not exclusively the aluminum level in water or food.
Toxicology Letters 10/2000; 117(1-2):45-52. · 3.23 Impact Factor
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M R Schetinger,
N M Porto,
M B Moretto,
V M Morsch,
J B da Rocha,
V Vieira,
F Moro,
R T Neis,
S Bittencourt,
H G Bonacorso,
N Zanatta
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ABSTRACT: This study examines the effect of new 1,5 benzodiazepines on acetylcholinesterase (AChE) and ATPDase (apyrase) activities from cerebral cortex of adult rats. Simultaneously, the effects of the classical 1,4-benzodiazepine on these enzymes were also studied for comparative purpose. The compounds 2-trichloromethyl-4-phenyl-3H-1,5-benzodiazepin and 2-trichloromethyl-4(p-methyl-phenyl)-3H- 1,5-benzodiazepin significantly inhibited acetylcholinesterase activity (p < 0.01) when tested in the range of 0.18-0.35 mM. The inhibition caused by these two new benzodiazepines was noncompetitive in nature. Similarly, at concentrations ranging from 0.063 to 0.25 mM, the 1,5 benzodiazepines inhibited ATP and ADP hydrolysis by synaptosomes from cerebral cortex (p < 0.01). However, the inhibition of nucleotide hydrolysis was uncompetitive in nature. Our results suggest that, although diazepam and the new benzodiazepines have chemical differences, they both presented an inhibitory effect on acetylcholinesterase and ATPDase activities.
Neurochemical Research 08/2000; 25(7):949-55. · 2.24 Impact Factor
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ABSTRACT: Brain ischemia followed by reperfusion causes neuronal death related to oxidative damage. Furthermore, it has been reported that subjects suffering from ischemic cerebrovascular disorders exhibit changes in circulating platelet aggregation, a characteristic that might be important for their clinical outcome. In the present investigation we studied tert-butyl hydroperoxide-initiated plasma chemiluminescence and thiol content as measures of peripheral oxidative damage in naive and preconditioned rats submitted to forebrain ischemia produced by the 4-vessel occlusion method. Rats were submitted to 2 or 10 min of global transient forebrain ischemia followed by 60 min or 1, 2, 5, 10 or 30 days of reperfusion. Preconditioned rats were submitted to a 10-min ischemic episode 1 day after a 2-min ischemic event (2 + 10 min), followed by 60 min or 1 or 2 days of reperfusion. It has been demonstrated that such preconditioning protects against neuronal death in rats and gerbils submitted to a lethal (10 min) ischemic episode. The results show that both 2 and 10 min of ischemia cause an increase of plasma chemiluminescence when compared to control and sham rats. In the 2-min ischemic group, the effect was not present after reperfusion. In the 10-min ischemic group, the increase was present up to 1 day after recirculation and values returned to control levels after 2 days. However, rats preconditioned to ischemia (2 + 10 min) and reperfusion showed no differences in plasma chemiluminescence when compared to controls. We also analyzed plasma thiol content since it has been described that sulfhydryl (SH) groups significantly contribute to the antioxidant capacity of plasma. There was a significant decrease of plasma thiol content after 2, 10 and 2 + 10 min of ischemia followed by reperfusion when compared to controls. We conclude that ischemia may cause, along with brain oxidative damage and cell death, a peripheral oxidative damage that is reduced by the preconditioning phenomenon.
Brazilian Journal of Medical and Biological Research 11/1999; 32(10):1295-302. · 1.13 Impact Factor
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ABSTRACT: The purpose of the present study was to investigate the in vitro and in vivo effects of aluminum sulfate on delta-aminolevulinic acid dehydratase (ALA-D) activity from the brain, liver and kidney of adult mice (Swiss albine). In vitro experiments showed that the aluminum sulfate concentration needed to inhibit the enzyme activity was 1.0-5.0 mM (N = 3) in brain, 4.0-5.0 mM (N = 3) in liver and 0.0-5.0 mM (N = 3) in kidney. The in vivo experiments were performed on three groups for one month: 1) control animals (N = 8); 2) animals treated with 1 g% (34 mM) sodium citrate (N = 8) and 3) animals treated with 1 g% (34 mM) sodium citrate plus 3.3 g% (49.5 mM) aluminum sulfate (N = 8). Exposure to aluminum sulfate in drinking water inhibited ALA-D activity in kidney (23.3 +/- 3.7%, mean +/- SEM, P < 0.05 compared to control), but enhanced it in liver (31.2 +/- 15.0%, mean +/- SEM, P < 0.05). The concentrations of aluminum in the brain, liver and kidney of adult mice were determined by graphite furnace atomic absorption spectrometry. The aluminum concentrations increased significantly in the liver (527 +/- 3.9%, mean +/- SEM, P < 0.05) and kidney (283 +/- 1.7%, mean +/- SEM, P < 0.05) but did not change in the brain of aluminum-exposed mice. One of the most important and striking observations was the increase in hepatic aluminum concentration in the mice treated only with 1 g% sodium citrate (34 mM) (217 +/- 1.5%, mean +/- SEM, P < 0.05 compared to control). These results show that aluminum interferes with delta-aminolevulinate dehydratase activity in vitro and in vivo. The accumulation of this element was in the order: liver > kidney > brain. Furthermore, aluminum had only inhibitory properties in vitro, while in vivo it inhibited or stimulated the enzyme depending on the organ studied.
Brazilian Journal of Medical and Biological Research 06/1999; 32(6):761-6. · 1.13 Impact Factor
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ABSTRACT: This study shows the effect of transient global cerebral ischemia (ISC) on hippocampal acetylcholinesterase (AChE) activity. Naive adult Wistar rats received either a brief (2 min) or a long (10 min) ischemic episode by the four-vessel occlusion method. Pre-conditioned rats received double ischemia: a 10 min episode inflicted 24 h after a 2 min event, a condition known to confer cytoprotection to CA1 pyramidal cells of hippocampus. 2 min of ischemia caused an increase in acetylcholinesterase activity both immediately and 30 min after the episode, however enzyme activity was significantly decreased after 24 h of reperfusion. 10 min of ischemia caused an increase in activity both 60 min and 24 h after ischemia. Conversely, pre-conditioned rats displayed lower activity both immediately and 60 min after ischemia. Our results suggest that: a) neuronal death, that follows 10 min of ischemia, is associated to a late increase in acetylcholinesterase activity; b) pre-conditioning is related to diminished acetylcholinesterase activity. This is in agreement with previous evidence that acetylcholinesterase inhibition and maintenance of acetylcholine levels are beneficial for cell surviving after cerebral ischemia.
Biochemistry and molecular biology international 04/1999; 47(3):473-8.
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ABSTRACT: 1. The effect of several central nervous system active drugs was studied in vitro on ATPase-ADPase activity and acetylcholinesterase (AChE) activity from the cerebral cortex of adult rats. 2. Lithium (1.0-10.0 mM) had no effect on either ATPase-ADPase or acetylcholinesterase activity. 3. Imipramine (0.5-5.0 mM), desipramine (0.5-5.0 mM), amitriptyline (0.1-1.0 mM) and diazepam (0.5-2.0 mM) inhibited ATP and ADP hydrolysis at all concentrations tested. 4. AChE activity was altered by imipramine (1.0-2.0 mM) and by diazepam (0.5-2.0 mM). 5. The possible participation of ATP diphosphohydrolase and AChE in the action of these drugs cannot be ruled out. The probable reduction of ATP, ADP and acetylcholine hydrolysis by the inhibitory effect of these drugs is discussed.
General Pharmacology 11/1998; 31(4):563-7.
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ABSTRACT: The modulatory effect of heparin and dextran sulfate 500,000 (sulfated polysaccharides) was studied on ATPDase and 5'-nucleotidase activities. These enzymes participate in the degradation of ATP and adenosine production at the synaptic cleft level. Nucleotide hydrolysis was inhibited by heparin and dextran sulfate 500,000. For ADP, the inhibition was more evident at low cation concentrations (0.15 mM Ca2+ or Mg2+), reaching a maximum of 75%. For ATP, the inhibitory effect was less prominent and independent of divalent cation concentration, reaching a maximum of 25%. For AMP, the inhibition observed was similar with either relatively high (1 mM) or with low Mg2+ concentrations tested (0.1 mM) and reached a maximum of 35%. K+ did not change the inhibitory potency of sulfated polysaccharide suggesting that its effects were not exclusively related to charge interaction. These results suggest that heparin and possibly other naturally occurring sulfated polysaccharides may have a potential role as modulator of extracellular nucleotide hydrolysis in the synaptic cleft region.
Neurochemistry International 10/1998; 33(3):243-9. · 2.86 Impact Factor
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ABSTRACT: 1. 9-Amino-1,2,3,4-tetrahydroacridine (THA), an acetylcholinesterase inhibitor, significantly inhibited in vitro the ATP diphosphohydrolase activity of synaptosomes from the cerebral cortex and hippocampus of adult rats. 2. THA did not inhibit in vitro the 5'-nucleotidase activity of synaptosomes from cerebral cortex and hippocampus of rats. 3. THA exerted an uncompetitive inhibition on ATP diphosphohydrolase activity. This mechanism of inhibition was the same in the 2 different synaptosomal fractions (cerebral cortex and hippocampus) studied. 4. THA, proposed as a drug for the treatment of Alzheimer's disease, can alter in vitro ATP degradation in synaptosomes from the central nervous system.
General Pharmacology 06/1997; 28(5):761-6.
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ABSTRACT: Aluminum chloride (AlCl3), a neurotoxic compound, inhibited ATP diphosphohydrolase activity of synaptosomes obtained from cerebral cortex of adult rats. The metal ion significantly inhibited ATPase and ADPase activities of the enzyme at all concentrations tested in vitro (0.01, 0.05, 0.5, 5, and 10 mM) in the presence of 1.5 mM calcium. When tested in the absence of Ca2+, and with increasing amounts of Al3+, enzyme activity remained below basal levels, suggesting that the trivalent cation Al3+ is not a substitute for the divalent cation Ca2+ in ATP-Ca2+ and ADP-Ca2+ complexes. The Al3+ inhibition was competitive with respect to Ca2+. The enzyme inhibition was reversed by the addition of deferoxamine (DFO). NaF significantly inhibited ATP diphosphohydrolase activity, and this inhibition was reversed by the addition of Ca2+ to the medium. Such inhibition was not potentiated by AlF4, which is an inhibitor of cation-transport ATPases.
Biological Trace Element Research 01/1996; 50(3):209-19. · 1.92 Impact Factor
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ABSTRACT: ATP diphosphohydrolase (apyrase) (EC 3.6.1.5) activity was measured in synaptosomes from cerebral cortex of Wistar rats of both sexes subjected to experimental phenylketonuria, i.e., chemical hyperphenylalaninemia induced by subcutaneous administration of 5.2 mumol phenylalanine/g body weight (twice a day) plus 0.9 mumol p-chlorophenylalanine/g body weight (once a day). ATP diphosphohydrolase specific activity (nmol Pi min-1 mg protein-1) of synaptosomes was significantly decreased compared to controls for both ATP (from 147.6 to 129.9) and ADP (from 70.2 to 63.1) hydrolysis one hour after single administration of the drugs to 35-day old rats. Chronic treatment was performed from the 6th to the 28th postpartum day. The enzyme specific activity of synaptosomes was measured one week after the last administration of the drugs and was significantly reduced compared to controls for both ATP (from 164.1 to 150.2) and ADP (from 76.3 to 62.1) hydrolysis. The in vitro effects of the drugs on the synaptosome enzyme specific activity were also investigated. Phenylalanine alone or associated with p-chlorophenylalanine significantly reduced enzyme specific activity for both ATP (from 150.2 to 136.0) and ADP (from 70.5 to 59.3) nucleotides as substrates. Since ADP diphosphohydrolase seems to play an important role in neurotransmission, these findings may be related to the neurological dysfunction characteristic of human phenylketonuria.
Brazilian Journal of Medical and Biological Research 07/1995; 28(6):643-9. · 1.13 Impact Factor
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ABSTRACT: The in vitro effects of phenylalanine and some of its metabolites on ATP diphosphohydrolase (apyrase, EC 3.6.1.5) activity in synaptosomes from rat cerebral cortex were investigated. The enzyme activity in synaptosomes from rats subjected to experimental hyperphenylalaninemia (alpha-methylphenylalanine plus phenylalanine) was also studied. In the in vitro studies, a biphasic effect of phenylalanine on both enzyme substrates (ATP and ADP) was observed, with maximal inhibition at 2.0 mM and maximal activation at 5.0 mM. Inhibition of the enzyme activity was not due to calcium chelation. Moreover, phenylpyruvate, when compared with phenylalanine showed opposite effects on the enzyme activity, suggesting that phenylalanine and phenylpyruvate bind to two different sites on the enzyme. The other tested phenylalanine metabolites phenyllactate, phenylacetate and phenylethylamine) had no effect on ATP diphosphohydrolase activity. In addition, we found that ATP diphosphohydrolase activity in synaptosomes from cerebral cortex of rats with chemically induced hyperphenylalaninemia was significantly enhanced by acute or chronic treatment. Since it is conceivable that ATPase-ADPase activities play an important role in neurotransmitter (ATP) metabolism, it is tempting to speculate that our results on the deleterious effects of phenylalanine and phenylpyruvate on ATP diphosphohydrolase activity may be related to the neurological dysfunction characteristics of naturally and chemically induced hyperphenylalaninemia.
Neurochemical Research 10/1994; 19(9):1175-80. · 2.24 Impact Factor
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ABSTRACT: ATP diphosphohydrolase (EC 3.6.1.5; apyrase) is an enzyme that can promote ATP and ADP hydrolysis to AMP plus inorganic phosphate and depends on divalent cations such as Ca2+ or Mg2+. In previous papers we described this enzyme in the synaptosomal fraction from the central and peripheral nervous system. The present report examines whether cadmium acetate could affect the in vitro activity of the enzyme in the synaptosomal fraction from the cerebral cortex of adult male Wistar rats. Cadmium (Cd2+), a heavy metal with neurotoxic effects, inhibited the enzyme in a concentration-dependent manner. All concentrations tested (0.05-1.0 mM) significantly inhibited the hydrolysis of both substrates (ATP and ADP), with the exception of 0.05 mM on ATP hydrolysis. The kinetic data indicate a noncompetitive inhibition between the cations Cd2+ and Ca2+.
Brazilian Journal of Medical and Biological Research 06/1994; 27(5):1111-5. · 1.13 Impact Factor
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ABSTRACT: Cerebral ischemia causes cell death of vulnerable neurons in mammalian brain. Wistar adult rats (male and female, weighing 180-280 g) were submitted to 2 min, 10 min, or to 2 and 10 min (separated by a 24-h interval) of transient forebrain ischemia by the four-vessel occlusion method. Animals subjected to the longer ischemic episodes had massive necrosis of pyramidal CA1 cells of the hippocampus, while animals receiving double ischemia (2 + 10 min) showed neuronal tolerance to the ischemic insult. ATP-diphosphohydrolase activity from hippocampal synaptosomes was assayed in these three groups (N = 6 animals/group) under two conditions: no reperfusion and 5-min of reperfusion. The control values for ATPase and ADPase activities were 144.7 +/- 18.8 and 60.6 +/- 5.24 nmol Pi min-1 mg protein-1, respectively. The 10-min group without reperfusion showed an enhancement of approximately 20% for ATPase and ADPase activities. In reperfused rats, only the 2-min group had a 20% increase in both enzymatic activities. We suggest that modulation of ATP-diphosphohydrolase activity might be involved in molecular events that follow both ischemia and reperfusion.
Brazilian Journal of Medical and Biological Research 06/1994; 27(5):1123-8. · 1.13 Impact Factor
