The in vivo and in vitro effects of L-carnitine supplementation on the erythrocyte membrane acetylcholinesterase, Na+, K+-ATPase and Mg2+-ATPase activities in basketball players.

BACKGROUND: We investigated whether the activities of erythrocyte membrane acetylcholinesterase (AChE), Na+, K+-ATPase and Mg2+-ATPase are modulated in basketball players pre- vs. post-forced training with or without L-carnitine (L-C) supplementation. METHODS: Blood was obtained from 10 male players pre-game (group A) and post-game (group B) and after 1 month L-C supplementation (2 g/24 h orally) pre-training (group C) and post-training (group D). Lactate, pyruvate and total antioxidant status (TAS) were measured with commercial kits, catecholamines with HPLC and the enzyme activities spectrophotometrically. RESULTS: Lactate, pyruvate, AChE, Na+, K+-ATPase and catecholamines were increased (p<0.001) and TAS was decreased (p<0.001) in group B. In contrast, TAS remained unaltered and the all enzyme activities were reduced (p<0.001) in group D at the same time of study. Mg2+-ATPase activity remained unchanged. In vitro incubation of the modulated AChE and Na+, K+-ATPase with L-C (25 microM) from group B and group D resulted in a non-significant reduction of the enzymes in group B and complete restoration of their activities in group D. CONCLUSIONS: The increase of AChE and Na+, K+-ATPase activities may be due to the elevation of catecholamines in group B. Carnitine utilization by the muscles during training may result in a reduction of the enzyme activities (group D). The latter is supported by the recovery of the enzyme activities after incubation of the membranes from group D with L-C.

L-cysteine supplementation prevents exercise-induced alterations in human erythrocyte membrane acetylcholinesterase and Na+,K+-ATPase activities.

BACKGROUND: L-Cysteine (L-Cys) is implicated in the reduction of free radical production. The aim of this study was to investigate whether L-Cys supplementation prevents modulation of the activities of erythrocyte membrane acetylcholinesterase (AChE), Na(+),K(+)-ATPase and Mg(2+)-ATPase induced by free radicals in basketball players during training. METHODS: Blood was obtained from 10 basketball male players before (group A) and after a game (group B) and after 1 week of L-Cys (0.5 g/24 h orally) supplementation before (group C) and after training (group D). Lactate, pyruvate and total antioxidant status (TAS) were measured using commercial kits and the enzyme activities were determined spectrophotometrically. RESULTS: Both lactate and pyruvate levels remarkably increased after exercise. In contrast, TAS levels significantly decreased in group B, increased in group C and then declined (group D), reaching those of group A. AChE activity was statistically increased post-exercise (3.98+/-0.04 Delta OD/min x mg protein) compared with pre-training (2.90+/-0.05 Delta OD/min x mg protein, p<0.01). Na(+),K(+)-ATPase activity was also higher post-exercise (1.27+/-0.05 micromol Pi/h x mg protein) than that pre-exercise (0.58+/-0.04 micromol Pi/h x mg protein, p<0.001). When the players were supplemented with L-Cys, both AChE and Na(+),K(+)-ATPase activities remained unaltered post-exercise. Mg(2+)-ATPase activities were unchanged in all groups studied. CONCLUSIONS: L-Cys supplementation may protect the enzyme activities studied against stimulation induced by free radical production during training in athletes by ameliorating their total antioxidant capacity.

Suckling rat brain regional distribution of acetylcholinesterase activity in galactosaemia in vitro.

We aimed to evaluate the effect of in vitro galactosaemia on acetylcholinesterase (AChE) activity in different suckling rat brain regions. Various concentrations of galactose (Gal), galactose-1-phosphate (Gal-1-P) and/or galactitol (Galtol) were preincubated for 1 h with homogenates from frontal cortex, hippocampus and for 1-3 h with hypothalamus homogenates at 37( composite function)C. AChE activity was determined spectrophotometrically. Mixture A (Gal-1-P (2 mM), Galtol (2 mM), and Gal (4 mM) (=brain concentrations in classical galactosaemia)) or mixture B (Galtol (2 mM) and Gal (1 mM) (=brain concentrations in galactokinase deficiency galactosaemia)) inhibited by 18-20% (P < 0.01) AChE activity in frontal cortex or hippocampus homogenates. Gal-1-P (2-8 mM) reduced AChE activity by 20% (P < 0.01) on frontal cortex and hippocampus homogenates. Galtol (2-8 mM) resulted in an AChE inhibition (20-22% (P < 0.01)) in hippocampus, 2 mM of the substance had the same effect (20%, P < 0.01) on frontal cortex, whereas higher concentrations (4-8 mM) failed to decrease the enzyme activity anymore. Gal (1-8 mM) did not change AChE activity in the studied areas. Additionally, the hypothalamus enzyme activity was measured considerably high and remained unaltered in the presence of the above compounds. In conclusion, AChE activity was significantly higher in hypothalamus compared with those in frontal cortex and hippocampus. Frontal cortex and hippocampus AChE was significantly inhibited by Gal derivatives, whereas hypothalamus AChE activity remained unaltered possibly due to the histologically different innervation of this area.

Suckling rat brain regional distribution of Na+,K+-atpase activity in the in vitro galactosaemia: the effect of L-cysteine and glutathione.

Inhibition of Na+,K+-ATPase activity causes edema and cell death in central nervous system. We determined the in vitro effects of galactose-l-phosphate (Gal-1-P), galactitol (Galtol) and galactose (Gal) (mix A = classical galactosaemia) or Galtol and Gal (mix B = galactokinase deficiency galactosaemia), on Na+,K+-ATPase activity in suckling rat brain frontal cortex, hippocampus or hypothalamus homogenates. Gal-1-P or Galtol alone at different concentrations, significantly inhibited Na+,K+-ATPase whereas Gal activated the enzyme in all investigated brain regions. Both mix A and mix B inactivated the enzyme by 20-30% (p < 0.001) in all studied areas. L-Cysteine (Cys) and glutathione (GSH) supplementation in mix B not only reversed the enzyme inhibition but also resulted in an activation of 50-60%, (p < 0.001) in all brain areas. Their presence in mix A also activated the inhibited Na+,K+-ATPase in hippocampus and hypothalamus to a lower degree, whereas Cys reversed the frontal cortex enzyme activity to control value only. These findings indicate that oxidation of the enzyme critical groups may be involved in galactosaemia, producing inhibitory effect. This phenomenon is reversed by antioxidants Cys and GSH, implying that free radicals may be implicated in the observed enzyme inactivation.

Mg2+-ATPase activity in suckling rat brain regions in galactosaemia in vitro. L-Cysteine and glutathione effects.

UNLABELLED: Mg2+-ATPase activity is implicated with Mg2+ homeostasis, maintaining high brain intracellular Mg2+ content. We determined the in vitro effects of galactose-1-phosphate (Gal-1-P), galactitol (Galtol) and galactose (Gal) {mix A=Gal-1-P(2 mM)+Galtol(2 mM)+Gal(4 mM) concentrations commonly found in patients with classical galactosaemia} or Galtol and Gal {mix B=Galtol(2 mM)+Gal(1 mM) concentrations usually measured in patients with galactokinase deficiency galactosaemia} on Mg2+-ATPase activity in suckling rat brain frontal cortex, hippocampus or hypothalamus homogenates. Gal-1-P significantly (p<0.001) enhanced enzyme activity in all the brain areas measured, whereas Galtol and Gal failed to cause any effect in the same regions. Mix A remarkably (p<0.001) stimulated Mg2+-ATPase in the studied areas. On the contrary, mix B had no effect. The supplementation of antioxidant l-cysteine (Cys) or reduced Glutathione (GSH) in mix A failed to reverse to normal the activated enzyme in frontal cortex and hypothalamus, while they significantly reduced Mg2+-ATPase activation in hippocampus. CONCLUSIONS: (a) Gal-1-P enormously activated Mg2+-ATPase in all the studied brain regions, (b) Mix A, also, excessively activated the enzyme in the same areas, (c) the production of free radicals may be implicated with the enzyme activation and (d) Cys or GSH significantly decreased the activated hippocampal Mg2+-ATPase.