Alpha-tocopherol supplementation prevents the exercise-induced reduction of serum paraoxonase 1/arylesterase activities in healthy individuals.

OBJECTIVE: To investigate PON 1/Aryl activities in basketball players with or without alpha-T supplementation pre- and post-training. Vitamin E (alpha-tocopherol, alpha-T) reduces lipid peroxidation. Paraoxonase 1/arylesterase (PON 1/Aryl) activities are closely related to oxidation and atherogenesis. SUBJECT/METHODS: Blood was obtained from 10 players pre- (group A), post-exercise (group B) and after 1 month on alpha-T (200 mg per 24 h orally) supplementation pre- (group C) and post-exercise (group D). Lactate, pyruvate, muscle enzyme activities, creatine kinase, lactate dehydrogenase and total antioxidant status (TAS) were measured with commercial kits. Catecholamines and alpha-T were determined with high-performance liquid chromatography methods and PON 1/Aryl activities spectrophotometrically. RESULTS: Lactate, pyruvate, muscle enzyme activities and catecholamines were increased (P<0.001) in all groups post-training. Alpha-T levels remained unaltered pre- vs post-exercise. TAS was decreased in all the groups post training. PON 1/Aryl activities were significantly decreased post-exercise (group B) (PON1: 65+/-12 U min(-1) ml(-1), Aryl: 58+/-14 KU min(-1) ml(-1)) as compared to those pre-exercise (group A) (PON1: 142+/-16 U min(-1) ml(-1), Aryl: 114+/-12 KU min(-1) ml(-1), P<0.001). In contrast, the studied enzyme activities remained practically unaltered after alpha-T supplementation pre- vs post-training. Both enzyme activities positively correlated to TAS (r=0.60, P<0.001). CONCLUSIONS: Alpha-T supplementation may result in protection of the enzyme PON 1/Aryl activities from free radical production.

The effect of basketball training on the players' erythrocyte membrane acetylcholinesterase, (Na+,K+)-ATPase and Mg2+-ATPase activities.

The aim of this study was to investigate whether the activities of erythrocyte membrane acetylcholinesterase (AChE), (Na (+),K (+))-ATPase and Mg (2+)-ATPase are modulated by a basketball training. Blood was obtained from 10 basketball players pre- and postexercise. Total antioxidant status (TAS), lactate and pyruvate concentrations were determined with kits, while the enzyme activities were determined spectrophotometrically. Post-training blood lactate and pyruvate concentrations as well as AChE (2.90 +/- 0.05 vs. 3.98 +/- 0.09 Delta OD/min . mg protein, p < 0.01) and Na (+),K (+)-ATPase (0.58 +/- 0.04 vs. 1.27 +/- 0.12 micromol Pi/h . mg protein, p < 0.001) activities were remarkably increased, whereas TAS was significantly decreased. Mg (2+)-ATPase activity remained unaltered at the end of the training. In conclusion, the stimulation of AChE and Na (+),K (+)-ATPase by the training may be due to the rise of blood catecholamine oxidation contributing to TAS decrease and/or the increase of serotonin levels. This stress condition may modulate cholinergic and catecholaminergic/serotoninergic functions in players.

The effect of L-cysteine and glutathione on inhibition of Na+, K+-ATPase activity by aspartame metabolites in human erythrocyte membrane.

BACKGROUND: Reports have implicated Aspartame (N-L-a-aspartyl-L-phenylalanine methyl ester, ASP) in neurological problems. AIM: To evaluate Na(+), K(+)-ATPase activities in human erythrocyte membranes after incubation with the ASP metabolites, phenylalanine (Phe), methanol (MeOH) and aspartic acid (Asp). METHODS: Erythrocyte membranes were obtained from 12 healthy individuals and were incubated at 37 degrees C for 1 h with the sum or each of the ASP metabolites separately, which are commonly measured in blood after ASP ingestion. Na(+), K(+)-ATPase and Mg(2+)-ATPase activities were measured spectrophotometrically. RESULTS: Membrane Mg(2+)-ATPase activity was not altered. The sum of ASP metabolite concentrations corresponding to 34, 150 or 200 mg/kg of the sweetener ingestion resulted in an inhibition of the membrane Na(+), K(+)-ATPase by -30, -40, -48%, respectively. MeOH concentrations of 0.14, 0.60 or 0.80 mM decreased the enzyme activity by -25, -38, -43%, respectively. Asp concentrations of 2.80, 7.60 or 10.0 mM inhibited membrane Na(+), K(+)-ATPase by -26, -40, -46%, respectively. Phe concentrations of 0.14, 0.35 or 0.50 mM reduced the enzyme activity by -24, -44, -48%, respectively. Preincubation with L-cysteine or reduced glutathione (GSH) completely or partially restored the inhibited membrane Na(+), K(+)-ATPase activity by high or toxic ASP metabolite concentrations. CONCLUSIONS: Low concentrations of ASP metabolites had no effect on Na(+), K(+)-ATPase activity. High or abuse concentrations of ASP hydrolysis products significantly decreased the membrane enzyme activity, which was completely or partially prevented by L-cysteine or reduced GSH.