Acute effects of resistance exercise and intermittent intense aerobic exercise on blood cell count and oxidative stress in trained middle-aged women

The aim of this study was to compare the effect of an intermittent intense aerobic exercise session and a resistance exercise session on blood cell counts and oxidative stress parameters in middle-aged women. Thirty-four women were selected and divided into three groups: RE group (performing 60 min of resistance exercises, N = 12), spinning group (performing 60 min of spinning, N = 12), and control group (not exercising regularly, N = 10). In both exercise groups, lymphocytes and monocytes decreased after 1-h recuperation (post-exercise) compared to immediately after exercise (P < 0.05). Immediately after exercise, in both exercised groups, a significant increase in TBARS (from 16.5 ± 2 to 25 ± 2 for the spinning group and from 18.6 ± 1 to 28.2 ± 3 nmol MDA/mL serum for the RE group) and protein carbonyl (from 1.0 ± 0.3 to 1.6 ± 0.2 for the spinning group and from 0.9 ± 0.2 to 1.5 ± 0.2 nmol/mg protein for the RE group) was observed (P < 0.05). A decrease in antioxidant activities (non-protein sulfhydryl, superoxide dismutase, catalase) was also demonstrated with a negative correlation between damage markers and antioxidant body defenses (P < 0.05). These results indicate that an acute bout of intermittent or anaerobic exercise induces immune suppression and increases the production of reactive oxygen species, causing oxidative stress in middle-aged and trained women. Furthermore, we demonstrated that trained women show improved antioxidant capacity and lower oxidative damage than sedentary ones, demonstrating the benefits of chronic regular physical activity.

Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase

This study analyses venom from the elapid krait snake Bungarus sindanus, which contains a high level of acetylcholinesterase (AChE) activity. The enzyme showed optimum activity at alkaline pH (8.5) and 45ºC. Krait venom AChE was inhibited by substrate. Inhibition was significantly reduced by using a high ionic strength buffer; low ionic strength buffer (10 mM PO4 pH 7.5) inhibited the enzyme by 1. 5mM AcSCh, while high ionic strength buffer (62 mM PO4 pH 7.5) inhibited it by 1 mM AcSCh. Venom acetylcholinesterase was also found to be thermally stable at 45ºC; it only lost 5% of its activity after incubation at 45ºC for 40 minutes. The Michaelis-Menten constant (Km) for acetylthiocholine iodide hydrolysis was found to be 0.068 mM. Krait venom acetylcholinesterase was also inhibited by ZnCl2, CdCl2, and HgCl2 in a concentrationdependent manner. Due to the elevated levels of AChE with high catalytic activity and because it is more stable than any other sources, Bungarus sindanus venom is highly valuable for biochemical studies of this enzyme.(AU)

Brain ischemia alters platelet ATP diphosphohydrolase and 5'-nucleotidase activities in naive and preconditioned rats

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

Ischemic preconditioning reduces peripheral oxidative damage associated with brain ischemia in rats

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

Effects of aluminum sulfate on delta-aminolevulinate dehydratase from kidney, brain, and liver of adult mice

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 per cent (34 mM) sodium citrate (N = 8) and 3) animals treated with 1 g per cent (34 mM) sodium citrate plus 3.3 g per cent (49.5 mM) aluminum sulfate (N = 8). Exposure to aluminum sulfate in drinking water inhibited ALA-D activity in kidney (23.3 + ou - 3.7 per cent, mean + ou - SEM, P<0.05 compared to control), but enhanced it in liver (31.2 + ou - 15.0 per cent, mean + ou - 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 + ou - 3.9 per cent, mean + ou - SEM, P<0.05) and kidney (283 + ou - 1.7 per cent, mean + ou - 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 per cent sodium citrate (34 mM) (217 + ou - 1.5 per cent, mean + ou - 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.

ATP diphosphohydrolase activity in synaptosomes from cerebral cortex of rats subjected to chemically induced phenylketonuria

ATP diphosphohydrolase (apyrase)(EC3.6.1.5) activity was measured in synaptosomes from cerebral cortex of Wistar rats of both sexes subjected to experimental phenylketonuria, i.e., chemical hyperphenylaninemia induced by subcutaneous administration of 5.2 µmol phenylalanine/g body weight (twice a day) plus 0.9 µmol 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. Phenylalnine 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 ATP diphosphohrolase seems to play an important role in neurotransmission, these findings may be related to the neurological dysfunction characteristic of human phenylketonuria

Activity of synaptosomal ATP diphosphohydrolase from hippocampus of rats tolerant to forebrain ischemia

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.

Inhibitory effect of cadmium acetate on synaptosomal ATP diphosphohydrolase (EC 3.6.1.5; apyrase) from adult rat cerebral cortex

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+.