L-Carnitine antioxidant effect on protein concentration, acetylcholinesterase, Na+,K+-ATPase
and Mg2+-ATPase activities in rat brain after forced swimming
Theodore Tsakiris1, Panagoula Angelogianni1, Christi Tesseromatis2, Stylianos Tsakiris1 ,* and
Kleopatra H. Schulpis3
1
Department of Experimental Physiology, Medical School, Athens University, P.O. Box 65257,
GR-15401 Athens, Greece
2
Department of Experimental Pharmacology, Medical School, Athens University, 75 Mikras Asias
Str., Goudi, GR-11527 Athens, Greece
3
Institute of Child Health, Research Center, “Aghia Sophia” Children's Hospital, GR-11527 Athens,
Greece
RUNNING TITLE: L-Carnitine effect on in swimming rat brain enzymes
Keywords: Carnitine, exercise, acetylcholinesterase, Na+,K+-ATPase, Mg2+-ATPase, oxidation,
free radicals
*
Corresponding author: S. Tsakiris, PhD, Associate Professor,
Tel: +302107462662 ; fax:+302107462571
e-mail adress: stsakir@cc.uoa.gr (S. Tsakiris)
INTRODUCTION
The determinants of human exercise performance are multifactorial and complex. The
performance of skeletal muscle work during exercise is dependent on the availability of
biochemical energy in the form of ATP. Thus, it is not surprising that a variety of metabolic and
biochemical markers are related to exercise performance and training [1,2] or that disorders of
energy metabolism are frequently associated with impaired exercise performance [3]. Similarly,
manipulations of bioenergetics have frequently been proposed as strategies to enhance exercise
endurance or capacity.
Carnitine is an endogenous molecule with well-established important roles in cellular metabolism
[4]. The functions of carnitine in skeletal muscle are critical to sustaining normal bioenergetics
during exercise. All biochemical actions of carnitine are based on the carnitine acyltransferasemeditated reversible transfer of carboxylic acids, or “acyl” groups, between carnitine and coenzyme
A in reactions of the following form:
Carnitine + Acyl-CoA ↔ Acylcarnitine + Coenzyme A
Coenzyme A is an important cofactor in a number of catabolic and anabolic reactions. Thus, the
carnitine pool consisting of carnitine, short-chain acylcarnitines (acylcarnitines corresponding to
short- and medium-chain length carboxylic acid groups), and long-chain acylcarnitines
(corresponding to long-chains length carboxylic acid), will dynamically interact with multiple
coenzyme A-dependent biochemical pathways.
Carnitine is required for mitochondrial long-chain faty acid oxidation [4], a major source of
energy during exercise [5]. Long-chain acylcarnitines transport activated long-chains fatty acids
into the mitochondrial matrix for β-oxidation. Short-chain acylcarnitines are generated from short-
chain acyl-CoAs. This generation of short-chain acylcarnitines may be viewed as buffering the
cellular coenzyme A pool from acyl-CoA accretion, as accumulation of short-chain acyl-CoAs may
adversely affect cellular metabolism [6]. The reversible transfer of short-chain acyl groups between
carnitine and coenzyme A occurs dynamically in muscle during exercise. For example, acetyl-
carnitine accumulation in muscle at workloads above the lactate threshold [8-10] corresponds to the
accumulation of acetyl-CoA in the muscle [11].
The important biochemical functions of carnitine and the altered muscle physiology
associated with clinical carnitine deficiency [7] support the critical role of carnitine in muscle
bioenergetics. However, the extrapolation of these established concepts to the effects of carnitine
supplementation in healthy persons or in varied pathologic conditions is less clear. It is unknown
whether supraphysiologic carnitine concentrations enhance exercise performance, or which
pathophysiologic conditions might be associated with decreased muscle carnitine content or
increased carnitine requirements [13,14].
Humans take in carnitine primarily from diet (75%) with the remaining 25% coming from
endogenous synthesis. Another major role for the carnitine is the transfer of acetyl-CoA from the
mitochondria into the cytoplasma, thereby providing acetyl groups in the synthesis of the
neurotransmitter acetylcholine (ACh) [15].
In keeping with polar characteristics, L-C does not bind to plasma proteins (factor unbound-1)
and enters erythrocytes very slowly. The uptake of L-C into most tissues of the body, including
liver, kidney, skeletal and cardial muscle, neurons and epididymal tissue, involves carrier-mediated
transport systems, which maintain high tissue-to-plasma concentration ratio [4]. The transport of
L-C from the plasma into the neurons is mediated by a Na+ and energy dependent process and may
involve the organic cation transporter [16,17].
The most widely established function for L-C is its obligate role in the transport of long-chain
fatty acids into mitochondrial matrix where they enter β-oxidation [18]. Studies in humans have
also demonstrated that a decrease on muscle free carnitine concentration occurs during short-
duration high intensity exercise and at the onset of exhaustive submaximal exercise and is matched
by an almost equivalent increase in acetylcarnitine [18]. These findings suggest that another
important role for carnitine is in buffering excess acetyl group accumulation, which occurs when
the rate of acetyl-CoA formation exceeds the rate at which the tricarboxylic acid cycle can recycle
CoA [19,20].
Acetylcholinesterase (AChE) (E.C. 3.1.1.7) is a biological significant component of cell
membrane, contributing to its integrity and to permeability changes occuring during synaptic
transmissions and conduction. It is a membrane-bound enzyme with its active side exposed in the
external leaflet of the bilayer (ectoenzyme). This enzyme participates in the hydrolysis of
acetylocholine (ACh) and can modulate the cholinergic function [21]. If ACh action is enhanced
and due to the wide spread distribution of cholinergic fuctions, toxic effects involve the
sympathetic, parasympathetic, motor and central nervous system [21,22].
Na+,K+-ATPase (E.C. 3.6.1.3) is the enzymatic base of univalent cation transport [23]. It is
implicated in neural excitability [24], metabolic energy production [25], uptake and release of
catecholamines [26] and serotonin [27]. Additionally, the role of Mg2+-ATPase is to control the
intercellular Mg2+ concentration, changes which can modulate the activity of Mg2+-dependent
enzymes and regulate the rate of protein synthesis and cell growth [28,29].
Previous in vitro studies implicated low total antioxidant status (TAS) (e.g. free radicals
production) with the activities of AChE, Na+,K+-ATPase and Mg2+-ATPase in rat brain [30,31]/
In addition, the above membrane enzyme activities were found modulated in the presence of the
free radicals [32,33].
Previous study [34] showed that free radicals production leading to a failure of mitochondria
function was ameliorated by L-C administration. Similarly, pretreatment with L-C enhanced trend
of AChE inhibition in all selected brain parts comparing with single galantamine administration, a
competitive AChe inhibition [35].
Since L-C action and free radicals production are closely related to ACh modulation, AChE
activity and Na+-dependent energy process, we aimed to investigate AChE, Na+,K+-ATPase and
Mg2+-ATPase activities in rat brain homogenates pre- and post-forced swimming before and after
L-
C administration. In addition, in an in vitro study, we aimed to find out a direct effect of L-C on the
above rat brain enzymes.
MATERIALS AND METHODS
Animal care and training protocol
Adult male Albino Wistar rats (Saint Savvas Hospital, Athens, Greece) were used in all
experiments. Body weight was 260 ± 27 g (mean ± SD). They were housed four in a cage, at a
constant room temperature (22 ± 1 oC) under a 12h light:12h dark (light 08:00 – 20:00h) cycle.
Food and water were provided ad libitum. Animals were cared for in accordance with the principles
of the “Guide for the Care and Use of Experimental Animals” [36].
Swimming was performed in a plastic waterpool (height 80 cm · width 50 cm and depth 55 cm),
at a water temperature of 22 oC - 23 oC, between 09:00 and 14:00h. Swimming duration was 0h
(animals were removed from the pool immediately after water immersion), 2h or 3h. Each of the
three groups consisted of seven animals. Venditti at al. [37] found that prolonged (8h) swimming of
rats induces oxidative stress, lipid peroxidation, and decreased antioxidant capacity in liver
homogenates, whereas swimming of moderate duration (3h) did not produce these effects.
However, the aim of our study was to evaluate the total antioxidant status, the protein concentration
and the enzyme activities in rat brain, which may be affected earlier than liver by exercise. So, the
above parameters were investigated under short (2h) or moderate (3h) swimming of rats. Control
animals (21 rats) were kept in their home cages at a constant room temperature (22 ± 1 oC) during
the period of exercise and seven rats for each group (0h, 2h or 3h) were used for tissue preparation
and biochemical determinations (group A).
In addition, groups of seven animals either were used as controls after L-C administration (300
mg/kg) ip [38] (group C) or were treated with 2h or 3h forced swimming as above.
Tissue preparation
Immediately after each treatment, rats were sacrificed by decapitation. The whole brain of each
animal was quickly removed and homogenized in 10 volume ice-cold (0-4 oC) medium containing
50mM tris(hydroxymethyl)-aminomethane-HCl (Tis-HCl), pH=7.4 and 30mM sucrose using an ice-
chilled glass homogenizing vessel at 900 rpm (4-5 strokes). Then, the homogenate was centrifuged
at 1000 x g for 10 min to remove nuclei and debris. In the resulting supernatant, the protein content
was determined according to the method of Lowry et al. [39] and then the total antioxidant status
(TAS) and enzymatic activities were measured. The enzyme incubation mixture was kept at 37 oC.
Incubation of rat brain homogenates in the presence or absence of L-Carnitine
100μg protein of rat brain homogenate from group B (3h) or group D (3h) were incubated with 50
mM Tris-HCl, pH 7.4, 120 mM NaCl in the presence or absence of L-C (5 mM) for 1h at 37 oC.
Then, AChE as well as Na+,K+-ATPase activities were evaluated in he reaction mixture [40,41]. L-
C (5 mM) concentration was adapted because this value expresses the mean valua of total
concentration in the vlood of healthy individuals in Greece, as previously reported (42].
Determination of brain total antioxidant status
TAS was evaluated in each homogenized fresh rat brain. The total antioxidant capacity was
measured spectrophotometrically by a commercial kit (Randox Laboratories Ltd., Cat. No.
NX2332, UK) as previously reported [43]. 2,2'-Azino-di-(3-ethylbenzthiazoline sulphonate)
(ABTS) was incubated with a peroxidase (met-myoglobin) and H2O2 in order to produce the radical
cation which was measured at 600 nm. Inhibited values of TAS reflect the increase in brain free
radical production, whereas stimulated TAS values show the decrease in free radical production and
the increase in the antioxidant compounds.
Determination of AChE activity
AChE activity was determined by following the hydrolysis of acetylthiocholine according to the
method of Ellman et al. [44] as described in detail previously [45]. The incubation mixture (1 ml)
contained 50 mM Tris-HCl, ph 8, 240 mM sucrose, and 120mM NaCl. Pseudocholinesterase
activity was not detected in the brain homogenate by using 2 · 10-2 mM quinidine sulfate in the
above reaction mixture. Protein concentration of the incubation mixture was 80 – 100 μg/ml. The
reaction was initiated after the addition of 0.03 ml of 5,5'-dithionitrobenzoic acid (DTNB) and 0.05
ml of acetylthiocholine iodide which was used as substrate. The final concentrations of DTNB and
substrate were 0.125 and 0.5 mM, respectively. The reaction was followed spectrophotometrically
by the increase of absorbance (Δ OD ) at 412 nm.
Determination of Na+,K+-ATPase and Mg2+-ATPase activities
Na+,K+-ATPase activity was calculated as the difference between total ATPase activity
(Na+,K+,Mg2+-dependent ATPase) and Mg2+-dependent ATPase activity. Total ATPase activity was
assayed in an incubation medium consisting of 50 mM Tris-HCl, ph 7.4, 120 mM NaCl, 20 mM
Kcl, 4 mM MgCl2, 240 mM sucrose, 1 mM ethylenediamine tetraacetic acid K2-salt (K+-EDTA), 3
mM disodium ATP, and 80 – 100 μg protein from the homogenate in a final volume of 1 ml.
Ouabain (1 mM) was added in order to determine the activity of Mg2+-ATPase. The reaction was
started by adding ATP and stopped after an incubation period of 20 min by the addition of 2 ml of
mixtyre consisting of 1% lubroil and 1% ammonium molybdate in 0.9 M H2SO4 [46]. The yellow
colour which developed was read at 390 mM.
Statistical Analysis
Data were analyzed by ANOVA or Student's t-test. P values of < 0.05 were considered
statistically insignificant.
RESULTS
As presented in Table 1, protein concentration in the homogenized whole brain was found
significantly decreased especially after 3h forced swimming whereas it remained unaltered in the
group with L-C administration at the same time of study.
As shown in Table 2, both TAS and AChE activity were remarkably decreased in the rat brain
after 3h forced exercise. After L-C administration, a significant increase was observed in TAS levels
and in AChE activities in controls followed by a significant reduction in TAS whereas AChE
activity was significantly decreased after 2h or 3h forced tranining.
As illustrated in Table 3, a remarkable increase of and Mg2+-ATPase activities
were measured in homogenized rat brain after exposed to forced swimming. In contrast, a
significant increase of Na+,K+-ATPase activity was observed 3h after forced training. In the group
with L-C administration, Mg2+-ATPase activities remained unaltered pre vs. post swimming in all
studied groups.
As shown in Table 4, both reduced enzyme activities restored to normal after incubation with L-C.
DISCUSSION
It is known that free radical production during prolonged exercise induces damage to skeletal and
cardial muscles as well as to liver [37]. The observed decrease in brain TAS during swimming
(group B, Table 2) shows the increase in free radical production and possibly the decrease in brain
antioxidant compounds under the described stress conditions. In contrast, TAS was slightly elevated
when the animals were administrated with L-C (pre- vs post- training). This finding could be due to
the well known antioxidant action of L-C [15]. Physical exercise increases ROS production, which
could cause damage to proteins and/or synaptosomal plasma membranes [47]. This phenomenon
may be implicated in the observed decrease in brain protein concentration during 2h and prolonged
(5h) forced swimming.
We have previously reported that free radicals are produced in the blood of phenylketonuric
patients “off diet” [43] and induce inhibition of their erythrocyte membrane AChE [48]. In addition,
we have suggested that this erythrocyte AChE inhibition may be due to diminished protein
synthesis. Furthermore, the AChE inhibition observed during the present treatment (group B) may
be due to diminished number of peripheral AChE sites on synaptosomal plasma membranes caused
by free radicals [49]. However, it cannot be excluded that a decrease ina acetylcholine may be
related to the above AChE inactivation. Furthermore, a decrease in acetylcholine release could be
induced by the observed Na+,K+-ATPase activation (Table 3), as suggested by Meyer and Cooper
[50]. This suggestion is supported by the findings of Fatranska et al. [51] who reported a significant
acetylcholine decrease in hippocampus and cerebral cortex after 20 min of forced swimming.
The observed brain Na+,K+-ATPase stimulation during rat swimming may be caused by increased
concentrations of catecholamines [52], serotonin [53] and/or corticosterone [54]. In a previous
study [55] we have observed a Na+,K+-ATPase activation in rat celebrum and cerebellum 3h after
the initiation of another kind of stress (cold and immobilization). Additionally, Carageorgiou et al.
[56] have found in vivo a whole rat brain Na+,K+-ATPase stimulation as a dose-dependent effect of
acute (8h) Cd administration. Similar effects were observed after a long-term (4-months) Cdinduced oxidative stress. On the other hand, a rat brain Na+,K+-ATPase inhibition was induced by
free radicals in in vitro experimental conditions [45]. It seems likely that there are two opposite
effects in rat brain Na+,K+-ATPase activity, closely depending on experimental conditions of stress,
a stimulatory effect produced by increased levels of catechomalines, serotonin and/or corticosterone
and an inhibitory one induced by free radicals. Fujino et al. [53] have reported an increased
serotonin release in mice frontal cortex and hippocampus induced by acute physiological stressors.
Glucocorticoids (cortisol) [10], catecholamines [58,59] and/or serotonin xan stimulate brain
Na+,K+-
ATPase. Moreover, modulation of brain protein synthesis could be produced by increased levels of
dopamine [60], corticosterone [61] and serotonin [62, 63], as in the case of the present exercise
stress. Finally, the observed Na+,K+-ATPase activation may cause modulation of brain neural
excitability [61] and metabolic energy production [59].
Interestingly, we paradoxically found a reduction of both rat brain enzymes, AChE, (Na+,K+)-
ATPase activities in the animals with L-C addition, post-training, although their TAS were
significantly elevated at the same time of study. As mentioned before, strenuous exercise increases
the production of free radicals associated with depletion of antioxidant defense [64]. In addition,
another study showed decreased free carnitine level in the blood after exercise [65]. There are many
factors which have to be taken into account when considerin changes in serum carnitine levels.
Such regulatory factors included changes in blood volume, cernitine uptake and release in the
muscle and acylation of carnitine outside the contracting muscle [65]. Although we did not measure
carnitine blood levels in the animals pre- vs post-exercise for technical reasons, a limitation of this
study, we may suggest that the inhibition of the studied enzymes in group D may be due to the
sudden depletion of carnitine from the blood due to its shunt into the exercising muscles as found
by other authors [65] and the simultaneous withdraw of its protection from the enzyme membrane
lipid peroxidation, since carnitine is a polar substance and enters the enzyme membrane. This
suggestion is further supported by our in vitro study: the decreased activities of the rat brain AChE
and Na+,K+-ATPase from group D were totally restored to normal after 1h incubation with L-C
concentration (5 mM) similar to that determined in the blood of healthy people [42]. The absence of
a significant alteration of the rat brain enzyme activities from group B after incubation with L-C
may be due to their long-lasting exposure into free radicals during training in the absence of L-C-
mediated membrane protection.
Brain Mg2+-ATPase activity was also found elevated during exercise/ We have suggested that
brain Mg2+-ATPase stimulation may be induced by free radical action. However, during prolonged
swimming of rats, we cannot exclude a decrease in glucose levels (hupoglycemia) [64], which may
further modulate Mg2+-ATPase. This enzyme activation increases intracellular Mg2+ concentration,
which may control rates of protein synthesis [65]. Such an alteration in brain protein synthesis may
also occur after prolonged swimming of rats, as found in the present study. This suggestion is
supported by the unaltered Mg2+-ATPase activity pre- vs post-swimming after L-C administration
and TAS normalization. Additionally, the stimulated Mg2+-ATPase (as an ectoenzyme) may also
modulate the availability of ATP and the activity of other extracellular ATP-dependent enzymes
(e.g. protein kinases). It is also proposed that Mg2+-ATPase may modulate the neurotransmitter role
of ATP [66]. From this point of view, we could assume that short and especially forced swimming
may have harmful effects on rat brain function.
In conclusion, forced swimming of rats induces oxidative stess, which may result in a reduction in
brain protein concentration and AChE activity. Increased activities of Na+,K+-ATPase and Mg2+-
ATPase were observed under the same experimental conditions. This type of stress may modulate
brain intracellular Mg2+ concentration, neural excitability, mtabolic energy production, as well as
cholinergic, catecholaminergic and/or serotoninergic mechanism(s). Carnitine supplementation may
result in an increase of antioxidant capacity and normalize the modulated activities of the studied
enzymes induced by forced training.
Acknowledgements
This study was funded by the university of Athens. Many thanks are expressed to Dr Filia
Stratigea (veterinary surgeon) and medical student Pantazopoulos Anastasios for their significant
assistance.
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Table 1. Changes in protein concentration in homogenized whole brain of rats (n = 7)
exposed to forced swimming for various periods with 300 mg/kg (group D) or without
(group B) L-Carnitine (L-C) administration.
Treatment
A-3h (in cage)
A0h
A2h
A3h
B0h
B2h
B3h
C-3h (in cage)
C0h
C2h
C3h
D0h
D2h
D3h
Protein concentration
(mg protein/ml)
5.80  0.40
6.00  0.24
6.15  0.50
5.70  0.42
5.90  0.38
(-2%)
5.22  0.20** (-15%)
3.99  0.15*** (-30%)
5.95  0.30
6.05  0.40
5.82  0.35
5.75  0.45
5.80  0.32
(-4%)
6.00  0.42
(+3%)
5.85  0.30
(+2%)
Each value indicates the mean  SD of seven independent experiments (seven rats per
group). The average of each experiment arose from three evaluations of the
homogenated brain of each animal.
Group A represents “nontreatment” control group and group C controls administered
L-C dose intraperitonally (ip). Values of controls with NaCl 0.9% (SC-3h and SC3h)
were not statistically different to that C-3h (data not shown).
Note: Only the statistically significant values are presented.
**: p < 0.01 (vs all controls), ***: p < 0.001 (vs all controls)
Table 2: Changes in total antioxidant status (TAS) and acetylcholinesterase (AChE)
activity in homogenized whole brain of rats (n = 7) exposed to forced swimming for
various periods with 300 mg/kg (group D) or without (group B) L-Carnitine (L-C)
administration.
Treatment
A-3h (in cage)
A0h
A2h
A3h
B0h
B2h
B3h
C-3h (in cage)
C0h
C2h
C3h
D0h
D2h
D3h
TAS
(mmol/l)
55.15  2.15n
53.85  1.19a
54.50  1.64b
52.15  2.05c
54.00  1.35d (+0.2%)
43.60  1.00e, ** (-20%)
39.11  1.17f, *** (-25%)
55.50  1.80h
56.70  2.40g
(+5%)
63.34  1.90i, ** (+16%)
64.62  2.10j, *** (+24%)
54.00  2.00k (-5%)
52.25  2.15l, ** (-18%)
54.51  1.80m, ** (-16%)
AChE
(ΔOD/min x mg protein)
0.906  0.045b
0.926  0.051a
0.916  0.035c
0.886  0.035d
0.888  0.045e
(-4%)
0.645  0.038f, ** (-30%)
0.576  0.032g , *** (-45%)
0.600  0.030i
0.636  0.038h
(+6%)
0.696  0.031j, * (+16%)
0.726  0.043k, ** (+21%)
0.629  0.029l (-1%)
0.668  0.040m (-4%)
0.600  0.031n, * (-17%)
Each value indicates the mean  SD of seven independent experiments (seven rats per
group). The average of each experiment arose from three evaluations of the
homogenated brain of each animal.
Group A represents “nontreatment” controls and group C controls administered L-C
dose intraperitonally (ip). Values of saline controls (SC-3h and SC3h) were not
statistically different as compared to SC3h (data not shown).
Note: Only statistically significant values are presented.
*: p < 0.05 (vs control) , **: p < 0.01 (vs control), ***: p < 0.001 (vs control)
TAS: a/e, a/f, a/i, a/j, a/m, n/e, n/j, n/l, n/m, b/e, b/j, b/i, b/f, c/f, b/c, c/e, c/j, c/h, c/g,
c/i = p < 0.01
AChE: a/f, a/g, a/h, a/i, a/j, a/k, a/l, a/m, a/n, b/f, b/g, b/n, b/i, b/j, b/k, b/l, b/m, b/n,
c/f, c/g, c/i, c/h, c/j, c/k, c/l, c/m, c/n, d/f, d/g, d/i, d/h, d/j, d/k, d/l, d/m, d/n = p <0.01
Table 3: Changes in Na+, K+-ATPase and Mg2+-ATPase activities in homogenized
whole brain of rats (n = 7) exposed to forced swimming for various periods with 300
mg/kg (group D) or without (group B) L-Carnitine (L-C) administration.
Treatment
A-3h (in cage)
A0h
A2h
A3h
B0h
B2h
B3h
C-3h (in cage)
C0h
C2h
C3h
D0h
D2h
D3h
Na+, K+-ATPase activity
Mg2+-ATPase activity
(μmol Pi / h x mg protein)
5.72  0.51a
7.30  0.78a
5.80  0.48b
7.44  0.66b
6.05  0.55c
7.52  0.60c
d
5.92  0.59
7.00  0.58d
6.00  0.36e (+3.4%)
7.20  0.65 (-3%)
f,
10.89  1.08 *** (+80%)
10.53  1.05e, *** (+40%)
g,
11.84  1.12 *** (+100%)
11.20  1.18f, *** (+60%)
3.08  0.24h
6.95  0.70
i
3.76  0.31 (+22%)
6.80  0.61 (-2%)
j,
4.19  0.40 ** (+36%)
6.83  0.65 (-2%)
5.11  0.56k, *** (+66%)
6.54  0.72 (-6%)
l
2.98  0.28 (-21%)
6.55  0.62 (-4%)
m,
2.80  0.28 ** (-33%)
6.70  0.60 (-2%)
n,
2.77  0.22 ** (-46%)
6.66  0.53 (+2%)
Each value indicates the mean  SD of seven independent experiments (seven rats per
group). The average of each experiment arose from three evaluations of the
homogenated brain of each animal.
Group A represents “nontreatment” control and group C controls administered L-C
dose intraperitonally (ip). Values of saline controls (SC-3h and SC3h) were not
statistically different as compared to that C-3h (data not shown).
Note: Only statistically significant values are presented.
**: p < 0.01 (vs control), ***: p < 0.001 (vs control)
Na+, K+-ATPase: a/f, a/g, a/h, a/i, a/j, a/l, a/m, a/n, b/f, b/g, b/h, b/i, b/j, b/l, b/m, b/n,
c/f, c/g, c/h, c/i, c/j, c/l, c/m, c/n, d/f, d/g, d/h, d/i, d/j, d/l, d/m, d/n = p < 0.01
Mg2+-ATPase: a/e, a/f, b/e, b/f, c/e, c/f, d/e, d/f = p < 0.001
Table 4: The effect of L-C (5 mM) incubation on the swimming rat brain AChE and
Na+, K+-ATPase activities with L-C (group D) or without L-C (group B)
administration post-3h-swimming (see Materials and Methods).
AChE activity
(ΔOD/min x mg prot)
Na+, K+-ATPase
activity
(μmol Pi/h x mg prot)
AChE activity
(ΔOD/min x mg prot)
Na+, K+-ATPase
activity
(μmol Pi/h x mg prot)
Control 3h
(group A)
0.886  0.035a
Swimming 3h
(group B)
0.576  0.032b
Group B 3h
+ L-C incubation
0.592  0.040e
5.92  0.59a
11.84  1.12b
11.14  0.95e
L-C Control 3h
(group C)
0. 726  0.043c
Swimming 3h
(group D)
0.600  0.031d
Group D 3h
+ L-C incubation
0.730  0.038f
5.11  0.56c
2.77  0.22d
5.00  0.48f
Values are expressed as mean  SD, for four different experiments.
AChE: a/b, a/e, c/d, d/f, = p < 0.001; b/e, c/f = NS
Na+, K+-ATPase: a/b, a/e, c/d, d/f, = p < 0.001; b/e, c/f = NS
NS= not statistically significant