Effect of L-carnitine supplementation and aerobic training on FABPc content and beta-HAD activity in human skeletal muscle


Lee, J.Kyu.; Lee, J.Sam.; Park, H.; Cha, Y-Soo.; Yoon, C.Su.; Kim, C.Keun.

European Journal of Applied Physiology 99(2): 193-199

2007


Both regular physical exercise and carnitine supplementation exert a role in energy metabolism and may improve endurance capacity. We investigated whether a combination of long-term carnitine ingestion and exercise training reveals any interactive effects on cytosolic fatty acid-binding protein (FABPc) expression and beta-hydroxyacyl CoA dehydrogenase (beta-HAD) activity in human skeletal muscle. Twenty-eight untrained healthy males randomly divided into four experimental groups: a placebo (CON; n = 7), exercise training (ET; n = 7, 40 min session(-1), five times per week at 60% VO2max), carnitine supplementation (CS; n = 7, 4 g day(-1)), and exercise training and carnitine supplementation (CT; n = 7). Before and after 6-week treatment, muscle biopsy samples were taken from the vastus lateralis. Nonesterified carnitine and acid-soluble acylcarnitine concentrations were increased in CT (P < 0.05), and serum triacylglycerol concentration was elevated almost twofold in ET and CT (P < 0.05). No interactive effects in FABPc expression were shown from any of treatment groups. Although FABPc increased by 54% in ET compared to CON, it failed to reach statistical significance. In addition, there was no change in FABPc expression from any of experimental groups. Similar trends with FABPc contents were demonstrated in beta-HAD activity. It is concluded that the combination of exercise training and L-carnitine supplementation does not augment in FABPc expression and beta-HAD activity in human skeletal muscle indicating that combined treatment does not exert additive effect in fat metabolism. Thus L-carnitine supplementation would be unlikely to be associated with the enhanced exercise performance.

Eur
J
Appl
Physiol
(2007)
99:193-199
DOI
10.1007/s00421-006-0333-3
ORIGINAL
ARTICLE
Effect
of
L-carnitine
supplementation
and
aerobic
training
on
FABPc
content
and
P-HAD
activity
in
human
skeletal
muscle
Jang
Kyu
Lee
Jong
Sam
Lee
Hyon
Park
Youn-Soo
Cha
Chung
Su
Yoon
Chang
Keun
Kim
Accepted:
11
October
2006
/
Published
online:
7
November
2006
©
Springer-Verlag
2006
Abstract
Both
regular
physical
exercise
and
carnitine
supplementation
exert
a
role
in
energy
metabolism
and
may
improve
endurance
capacity.
We
investigated
whether
a
combination
of
long-term
carnitine
ingestion
and
exercise
training
reveals
any
interactive
effects
on
cytosolic
fatty
acid-binding
protein
(FABPc)
expres-
sion
and
13-hydroxyacyl
CoA
dehydrogenase
((3-HAD)
activity
in
human
skeletal
muscle.
Twenty-eight
untrained
healthy
males
randomly
divided
into
four
experimental
groups:
a
placebo
(CON;
n
=
7),
exercise
training
(ET;
n
=
7,
40
min
session
-t
,
five
times
per
week
at
60%
VO2max),
carnitine
supplementation
(CS;
n
=
7,
4
g
day
-
'),
and
exercise
training
and
carnitine
supplementation
(CT;
n
=
7).
Before
and
after
6-week
treatment,
muscle
biopsy
samples
were
taken
from
the
J.
K.
Lee
C.
K.
Kim
(21)
Department
of
Human
Physiology,
Korea
National
Sport
University,
88-15
Oryun-dong,
Songpa-gu,
Seoul,
South
Korea
e-mail:
ckkim2006@yahoo.co.kr
J.
S.
Lee
Department
of
Physical
Education,
Daegu
University,
Daegu,
South
Korea
H.
Park
Department
of
Sport
Medicine,
Kyunghee
University,
Suweon,
South
Korea
Y.-S.
Cha
Department
of
Food
Science
and
Human
Nutrition
and
Research
Institute
of
Human
Ecology,
Chonbuk
National
University,
Jeonju,
South
Korea
C.
S.
Yoon
Department
of
Physical
Education,
Chonbuk
National
University,
Jeonju,
South
Korea
vastus
lateralis.
Nonesterified
carnitine
and
acid-solu-
ble
acylcarnitine
concentrations
were
increased
in
CT
(P
<
0.05),
and
serum
triacylglycerol
concentration
was
elevated
almost
twofold
in
ET
and
CT
(P
<
0.05).
No
interactive
effects
in
FABPc
expression
were
shown
from
any
of
treatment
groups.
Although
FABPc
increased by
54%
in
ET
compared
to
CON,
it
failed
to
reach
statistical
significance.
In
addition,
there
was
no
change
in
FABPc
expression
from
any
of
experimental
groups.
Similar
trends
with
FABPc
contents
were
dem-
onstrated
in
I3-HAD
activity.
It
is
concluded
that
the
combination
of
exercise
training
and
L-carnitine
sup-
plementation
does
not
augment
in
FABPc
expression
and
I3-HAD
activity
in
human
skeletal
muscle
indicat-
ing
that
combined
treatment
does
not
exert
additive
effect
in
fat
metabolism.
Thus
L-carnitine
supplementa-
tion
would
be
unlikely
to
be
associated
with
the
enhanced
exercise
performance.
Keywords
Regular
exercise
Lipid
metabolism
Introduction
Neither
the
long-chained
fatty
acids
nor
their
CoA
derivates
are
readily
transported
across
the
inner
mitochondrial
membrane.
To
facilitate
transport,
fatty
acyl-CoA
react
with
carnitine
to
form
fatty
acylcarnitine
in
a
reaction
catalyzed
by
carnitine
palmitoyltransfer-
ase
(CPT)
I
and,
once
in
the
mitochondrion,
are
recon-
verted
to
fatty
acyl-CoA
by
CPT
II
located
in
the
outer
and
inner
membranes.
In
doing
so,
carnitine
plays
an
essential
role
for
the
transportation
of
fatty
acyl
groups
from
the
cytoplasm
into
the
mitochondrion
and
it
may
be
rate
limiting
for
fat
oxidation.
it
Springer
194
Eur
J
Appl
Physiol
(2007)
99:193-199
Ingestion
of
L-carnitine
increases
the
plasma
L-carni-
tine
concentration
but
the
muscle
carnitine
remains
unchanged
(Barnett
et
al.
1994;
Brass
et
al.
1994;
Natali
et
al.
1993;
Soop
et
al.
1988;
Vukovich
et
al.
1994).
Fur-
thermore,
L-carnitine
does
not
decrease
after
pro-
longed
exercise
or
severe
training
(Decombaz
et
al.
1993,
1992)
and
athletes
would
be
expected
to
maintain
an
adequate
carnitine
status.
In
spite
of
this
a
positive
effect
of
L-carnitine
ingestion
on
exercise
performance
has
been
reported
(Dragan
et
al.
1987;
Marconi
et
al.
1985;
Natali
et
al.
1993;
Siliprandi
et
al.
1990;
Vecchiet
et
al.
1990),
while
others
have
shown
no
beneficial
effects
of
either
ingested
or
intravenously
administered
L-carnitine,
including
effects
on
substrate
utilization
(Brass
and
Hoppel
1994;
Colombani
et
al.
1996;
Heinonen
1996;
Heinonen
et
al.
1992;
Soop
et
al.
1988;
Trappe
et
al.
1994;
Wyss
et
al.
1990).
Additional
carnitine
stores
could,
however,
be
of
benefit
to
athletic
performance
and
a
number
of
stud-
ies
have
focused
on
exercise
endurance
following
L-car-
nitine
supplements
to
increase
fat
oxidation
and
reduce
the
reliance
on
endogenous
carbohydrate
stores
(Bar-
nett
et
al.
1994;
Brass
and
Hoppel
1994;
Gorostiaga
et
al.
1989;
Heinonen
1996;
Heinonen
et
al.
1992;
Maassen
et
al.
1995;
Marconi
1985;
Soop
et
al.
1988;
Trappe
et
al.
1994;
Vukovich
et
al.
1994;
Wyss
et
al.
1990).
Most
of
these
studies
have
measured
fatty
acid
oxidation
during
exercise
using
indirect
calorimetry.
Such
measurements
may
be
inadequate
to
assess
the
capacity
for
fat
oxidation
since
a
given
exercise
bout
may
not
drive
fat
oxidation
to
its
limit.
Therefore,
we
studied
the
effects
of
carnitine
supplementation
and
exercise
training
on
the
capacity
of
muscles
for
fat
oxidation.
The
relative
distribution
of
muscle
fiber
types
is
an
indicator
of
oxidative
capacity
and
the
types
of
fuels
that
are
most
effectively
utilized.
Muscle
biopsies
were
therefore
obtained
before
and
after
training
and
sup-
plementation
and
the
influence
of
fiber
composition
integrated
in
the
analysis.
Biochemical
indices
of
fatty
acid
oxidative
capacity
were
assayed
including
the
determination
of
fatty
acid-binding
protein
(FABPc)
as
an
indicator
of
the
capacity
for
fatty
acid
oxidation
in
muscle
and
the
activity
of
fl-hydroxyacyl
CoA
dehydrogenase.
Methods
Twenty-eight
healthy
males
volunteered
as
subjects
and
were
randomly
divided
into
four
groups
(Table
1):
a
placebo
control
group
(CON;
n
=
7),
a
non-supple-
mented
exercise-trained
group
(ET;
n
=
7),
a
L-carni-
Table
1
Age,
body
mass,
and
percent
body
fat
of
subjects
Group
Trial
Height
(cm)
Body
mass
(kg)
%
Body
fat
CON
pre
177.1
(5.1)
73.6
(11.9)
16.8
(4.7)
post
177.1
(5.1)
74.4
(11.6)
16.8
(4.1)
ET
pre
175.4
(6.7)
71.7
(6.7)
14.5
(4.8)
post
175.6
(6.6)
72.1
(6.6)
13.6
(3.9)
CS
pre
175.8
(5.2)
77.0
(11.1)
18.7
(4.8)
post
175.8
(5.2)
76.6
(11.0)
17.9
(43)
CT
pre
178.1
(5.2)
78.4
(6.7)
17.9
(23)
post
178.1
(5.2)
78.8
(6.8)
17.7
(2.6)
All
values
are
means
(SEM)
CON
a
placebo
control
group,
ET
regular
exercise
training
group;
CS
carnitine
supplementation
group,
CT
regular
exercise
training
and
carnitine
supplementation
group
tine
supplemented
group
(CS;
n
=
7),
and
an
exercise
trained
with
L-carnitine
supplementation
group
(CET;
n
=
7).
All
experimental
procedures
were
approved
by
the
Human
Research
Ethics
Committee
of
Korea
National
Sport
University,
and
the
subjects
gave
their
written
consent
to
participate
in
this
study.
Experimental
design
The
ET
and
CET
subjects
trained
for
40
min
on
a
bicy-
cle
ergometer
at
60%
of
maximal
oxygen
uptake
(V0
2
.),
five
times
per
week
for
6
weeks.
The
sup-
plemented
groups
received
4
g
day
-1
of
L-carnitine
as
L-carnitine-tartrate.
The
dosage
chosen
has
been
reported
to
effectively
modulate
fat
metabolism
(Dra-
gan
et
al.
1987;
Marconi
et
al.
1985).
Muscle
biopsy
Muscle
samples
were
obtained
from
the
vastus
lateralis
from
the
preferred
leg
using
the
percutaneous
needle
biopsy
technique
of
Bergstrom
(1962)
following
local
anaesthesia
to
the
skin.
Muscle
samples
were
divided
into
two
portions.
One
portion
was
immediately
mounted
in
an
embedding
medium
(O.C.T.
compound
Tissue-Tek,
Lab-Tek
products,
Naperville,
IL,
USA),
and
then
frozen
in
pre-cooled
isopentane.
The
other
portion
was
frozen
in
liquid
nitrogen
for
further
use.
All
muscle
samples
were
stored
at
-80°C
until
analyzed.
Histochemistry
Serial
transverse
sections
(10
um)
were
cut
at
-20°C
in
a
Cryocut.
The
sections
were
mounted
on
a
cover-
slip
and
stained
for
myofibrillar
ATPase
at
pH
9.4
after
both
alkaline
(pH
10.3)
and
acidic
(pH
4.3
and
pH
4.6)
preincubations
(Brooke
and
Kaiser
1970).
Muscle
fibers
(range
243-392)
were
analyzed
and
it
Springer
Eur
J
Appl
Physiol
(2007)
99:193-199
195
characterized
as
type
I,
type
Ha,
and
type
IIx.
Capil-
lary
supply
surrounding
the
different
types
of
fibers
was
visualized
using
periodic-PAS
staining.
Muscle
fiber
type
composition,
cross-sectional
area
(CSA),
capillary
density,
the
capillary
to
fiber
ratio,
and
diffu-
sional
area
were
determined
using
image
analyzer
(COMFAS,
Denmark).
Cytosolic
FABPc
measurement
Portions
of
muscle
(15-30
mg)
were
homogenized
for
30
s
in
ice-cold
buffer
containing
25
mM
Tris/HC1
(pH
6.8),
1%
SDS,
5
mM
EGTA,
50
mM
NaF,
10%
Glycerol,
and
1
mM
Vanadate
using
a
motor-driven
homogenizer
(Ultra-Turrax
T8,
IKA,
Germany).
The
homogenates
were
heated
for
10
min
at
90°C,
vor-
texed,
and
centrifuged
at
7,000
x
g
for
10
min
at
4°C.
Supernatants
were
removed
and
protein
content
was
determined
by
use
of
a
commercially
available
kit
(Micro
BCA
protein
assay
reagent
kit,
Pierce,
Rock-
ford,
IL,
USA).
The
supernatant
was
diluted
with
Lae-
mmli
sample
buffer
composed
of
0.75
M
Tris—HC1
(pH
6.8),
25%
glycerol,
0.00025%
Bromophenol,
25
mM
DTT,
5%
SDS,
5%
13-Mercaptoethanol,
and
stored
at
—80°C
until
analyzed.
Aliquots
of
muscle
homogenates
containing
7
µg
of
protein
were
separated
by
Sodium
Dodecyl
Sulfate-Polyacrylamide
Gel
Electrophoresis
(SDS-PAGE;
15%
resolving
gel),
transferred
for
1
h
(at
100
V
and
350
mA)
to
polyvinylidenedifluoride
(PVDF)
membranes
(MSI,
0.45
pm,
Osmonics),
and
blocked
for
2
h
with
5%
nonfat
milk.
Along
with
sam-
ple
homogenates,
4
µg
protein
extracted
from
rat
myo-
cardium
was
run
to
identify
the
FABPc
protein.
Membranes
were
incubated
for
2
h
at
room
tempera-
ture
with
primary
antibody
(1:500
dilution,
Mouse
IgG1,
Cat.
No.
HM2016,
Hbt
Products,
The
Nether-
lands)
that
was
mixed
in
a
solution
containing
tween
azide
and
0.05%
skim
milk
powder.
After
washing
three
times
in
TBST
(Tris
Buffered
Saline
Twin)
(0.05%
tween),
each
membrane
was
incubated
with
secondary
antibody
(Goat
Anti-Mouse
IgG,
1:6000,
M30208,
Caltag
Products,
USA)
for
1
h
at
room
tem-
perature
(25°C).
Following
three
washes
in
TBST,
BCIP/NBT
substrate
kit
(Vector
Laboratories
Prod-
ucts,
CA,
USA)
was
used
to
visualize
FABPc
bands
on
the
membranes.
The
FABPc
bands
were
quantified
by
using
densitometry
analysis
(Image
Master
1D
Prime,
Amersham
pharmacia
biotech,
Sweden).
Analysis
of
13-HAD
activity
13-HAD
activity
was
analyzed
using
acetoacetyl-CoA
as
a
substrate.
The
change
in
absorbance
(i.e.,
dis-
appearance
of
NADH)
per
minute
was
observed
at
340
nm
using
a
Smartspec
3000
spectrophotometer
(BIO-RAD,
USA).
A
portion
of
wet
muscle
sample
(5-15
mg)
was
cut
in
a
Cryocut
(-20°C),
and
weighed
to
the
fifth
decimal.
Muscle
samples
were
then
homo-
genized
(1:100
dilution)
in
buffer
[containing
0.175
M
KC1,
2
mM
EDTA
(pH
7.4)]
with
a
hand-held
polytron
homogenizer
(Ultra-Turrax
T8,
IKA,
Germany).
Once
homogenized,
the
sample
was
frozen
immediately
in
liquid
N
2
.
When
all
samples
were
homogenized,
they
were
thawed
at
37°C.
Two
additional
freeze-thawing
procedures
were
then
performed
to
disrupt
mitochon-
drial
membrane
and
release
oxidative
enzymes
from
the
mitochondrial
matrix.
The
samples
were
then
cen-
trifuged
for
2
min
(at
4,000
rpm)
and
the
supernatant
collected,
and
stored
at
—80°C
until
analyzed.
For
13-HAD
activity,
a
reagent
cocktail
was
freshly
prepared
containing
1
M
Tris-HC1
(pH
7.0),
200
mM
EDTA,
5
mM
NADH
and
10%
triton-X.
For
the
blank,
50
µI
of
sample
homogenate
(without
substrate)
was
added
to
450
µI
of
reagent
cocktail,
and
the
change
in
absorbance
over
3
min
recorded.
When
blank
values
showed
no
significant
drift,
10
µI
of
acetoacetyl-CoA
was
added
along
with
50
µI
of
sample
homogenate
and
mixed
thoroughly.
Enzyme
activity
was
calculated
using
molar
extinction
coefficient
of
6.22
at
340
nm
for
a
1
mM
solution
of
NADH.
The
temperature
of
the
assay
was
25°C.
Carnitine
assay
Nonesterified
carnitine
(NEC),
acid-soluble
acylcarni-
tines
(ASAC)
and
acid-insoluble
acylcarnitines
(AIAC)
in
serum
were
determined
by
a
modified
radio-enzymatic
method
which
was
originally
proposed
by
Cederblad
and
Lindstedt
(1972)
and
modified
by
Sachan
et
al.
(1984).
Briefly,
AIAC
was
precipitated
with
perchloric
acid
and
collected
after
centrifugation
for
AIAC
analysis.
The
supernatants
were
transferred
into
new
tubes
and
aliquoted
into
two
portions.
One
portion
of
the
supernatant
was
used
to
determine
the
NEC
and
the
other
was
hydrolyzed
with
0.5
M
KOH
and
used
to
determine
total
acid-soluble
carnitine
(i.e.,
ASAC
+
NEC).
ASAC
was
calculated
as
the
difference
between
the
NEC
and
the
total
acid-soluble
carnitine.
The
pellets
containing
the
AIAC
were
drained,
washed,
and
hydrolyzed
in
0.5
M
KOH
for
60
min
in
a
hot
water
(60°C).
In
each
case
carnitine
was
assayed
by
using
carnitine
acetyltransferase
(Sigma,
USA)
to
esterify
carnitine
with
[1-
14
C]acetyl
CoA
(Amersham,
UK)
forming
[
14
C]acetylcarnitine.
The
radioactivity
of
the
samples
was
determined
using
a
Beckman
LS3801
liquid
scintillation
counter (Palo
Alto,
USA).
it
Springer
196
Eur
J
Appl
Physiol
(2007)
99:193-199
Statistical
analysis
Results
are
presented
as
means
±
standard
error
(SEM).
Two-way
analysis
of
variance
with
repeated
measures
and
Newman-Keuls
post
hoc
test
were
administered
to
identify
differences
between
treat-
ments.
Statistical
significance
was
accepted
at
the
level
of
P<
0.05.
Results
There
was
no
significant
change
in
anthropometric
mea-
surements,
including
percent
body
fat
(%fat)
over
the
training
period
(Table
1).
After
6
weeks
of
the
interven-
tion,
the
concentration
of
NEC
was
increased
only
in
the
CET
(Table
2)
The
ASAC
concentration
was
increased
in
both
CS
[59.7
(pre)
vs.
82.4
mM
(post)]
and
CT
(57.5
vs.
86.5
mM),
but
no
significant
changes
were
found
in
CON
and
ET.
Also
no
significant
changes
in
AIAC
con-
centration
were
found
among
the
experimental
groups
(Table
2).
Serum
triacylglycerol
concentrations
were
increased
almost
twofold
in
ET
and
CET
after
treat-
ment,
while
L-carnitine
supplementation
alone
(CS)
had
no
significant
effect
on
the
serum
triaclyglycerol
concen-
tration
(Fig.
la).
Serum
total
cholesterol
was
reduced
in
ET
and
CS
subjects,
but not
in
the
CET
(Fig.
lb).
After
6
weeks
of
training,
the
percentage
of
type
I
fibers
remained
unchanged
in
all
groups
apart
from
ET
which
showed
an
increase
of
33%
at
the
expense
of
a
decrease
in
type
II
fibers
(28%).
The
frequency
of
type
Ha
fibers
in
CET
subjects
increased
at
the
expense
of
type IIx
fibers.
The
CSA
in
different
fiber
types
remained
unchanged
with
training
in
all
groups
apart
from
CET
where
an
increase
in
type
Ila
and
type
IIx
muscle
fibers
was
observed
(Table
3).
The
content
of
FABPc
was
unchanged
with
training
although
this
tended
to
increase
in
the
ET
(35%)
and
decrease
in
CON
(21%)
subjects
(Fig.
1d).
I3-HAD
activity
remained
unchanged
in
all
groups
(Fig.
1c).
In
CON,
I3-HAD
activity
was
2.20
±
0.51
µmol
-1
g
-1
min
and
2.52
±
0.51
µmol
-1
g
-1
min
(pre
vs.
post).
I3-HAD
activity
again
failed
to
show
any
change
in
ET
even
when
regular
exercise
was
performed
(2.71
±
0.77
and
2.90
±
0.97
µmol
-1
g
-1
min,
pre
vs.
post,
respectively).
Similar
results
were
obtained
when
carnitine
was
ingested
for
6
weeks.
Before
carnitine
supplementa-
tion,
I3-HAD
activity
was
2.81
±
0.72
µmol
-1
g
-1-
min
and
following
2.73
±
0.88
µmol
-1
g
-1-
min.
There
was
an
18%
increase
in
I3-HAD
activity
after
two
the
treat-
ments
(training
+
supplimentation)
were
combined
(2.47
±
0.80
and
2.90
±
1.22
µmol
-1
g
-1-
min;
pre
vs.
post)
but
again
this
was
not
statistically
significant.
Discussion
The
major
finding
of
the
present
study
is
that
carnitine
supplementation
had
an
additive
effect
on
phenotypic
changes
in
muscle
fiber
type
and
fiber
size
when
com-
bined
with
training,
but
that
did
not
induce
any
addi-
tional
positive
effect
on
fat
metabolism.
Muscle
carnitine
concentration
is
unchanged
after
carnitine
supplementa-
tion,
even
though
the
level
of
carnitine
in
plasma
is
increased
(Branett
et
al.
1994;
Brass
et
al.
1994;
Natali
et
al.
1993;
Trappe
et
al.
1994;
Vukovich
et
al.
1994).
Miller
et
al.
(2002)
demonstrated
that
supplementation
with
L-carnitine
(3
g
day
-1
)
increased
the
total
serum
L-
carnitine
concentration,
but not
the
concentration
of
the
acyl
L-carnitine
supporting
the
present
results.
Free
serum
L-carnitine
(NEC)
and
ASAC
were
increased
in
CSG
and/or
CTG.
However,
AIAC
did
not
show
any
statistical
change.
Although
these
changes
were
positive,
Table
3
Mean
occurrence
(%)
and
cross-sectional
area
(pm
2
)
of
muscle
fiber
types
after
6
weeks
training
*Significantly
different
from
pre
values
in
same
experimen-
tal
group
(P
<
0.05)
Group
Trial
Type
I
Type
IM
Type
IIx
CON
pre
51.9
(1.2)
15.1
(3.9)
32.0
(6.5)
post
38.6
(7.2)*
28.9
(10.1)
33.2
(11.7)
ET
pre
35.3
(0.2)
31.8
(4.3)
32.9
(43)
post
46.9
(3.7)*
23.0
(5.1)*
30.1
(7.8)
CS
pre
49.7
(4.5)
20.4
(1.2)
29.8
(4.9)
post
53.9
(7.0)
13.2
(4.4)
32.9
(53)
CT
pre
30.1
(7.9)
20.4
(1.5)
49.4
(7.7)
post
30.6
(8.6)
40.1
(4.5)*
29.2
(4.1)*
CON
pre
3685.0
(592.8)
3744.3
(822.5)
5028.3
(584.8)
post
3318.5
(223.8)
4287.5
(229.2)
4888.5
(310.5)
ET
pre
4121.6
(977.9)
3637.3
(1084.2)
4685.0
(581.7)
post
4369.5
(1237.0)
3815.2
(925.3)
4957.0
(1075.5)
CS
pre
4713.3
(599.3)
4649.0
(846.6)
5181.3
(377.8)
post
4080.2
(578.3)
3907.7
(744.7)
4708.7
(389.2)
CT
pre
3690.3
(1148.7)
3047.0
(133.7)
4118.6
(208.5)
post
4799.3
(671.4)
4958.6
(233.8)*
6070.6
(519.5)*
it
Springer
197
A
(mg.d
C
I
)
150
=
120
pre
B
Enos
t
(mg.d
250
200
o
-
0
90
g
5
,
=1
0
60
§
Es
.100
E,
8
30
I-
0
0
CON
ET
CS
CT
CON
Er
CS
CT
C
(µmoll.min
-1
)
D
5
60
3
O.
50
=
dy
40
a
a
x
iom
2
2
30
e
E
20
E
j
10
0
0
Eur
J
Appl
Physiol
(2007)
99:193-199
Fig.
1
Serum
triacylglycerol
(a),
total
cholesterol
concen-
trations
(b),
13-HAD
activity
(c)
and
FABPc
content
(d).
*Significantly
different
from
pre
values
in
same
experimen-
tal
group
(P
<
0.05).
CON
a
placebo
control
group,
ET
a
regular
exercise
training
group,
CS
carnitine
supple-
mentation
group,
CT
regular
exercise
training
plus
carni-
tine
supplementation
group.
Assays
a,
b
were
performed
by
the
lipase-glycerol
phos-
phate
method
as
described
in
Methods.
Assay
c
was
per-
formed
at
25°C
and
final
val-
ues
were
made
based
on
the
disappearance
of
NADH
in
spectrophotometer,
and
val-
ues
in
d
are
expressed
as
per-
centage
of
rat
myocardium
standard
(4
µg).
Values
are
means
(SEM)
Con
Er
CS
CT
CON
Er
CS
CT
Table
2
Serum
carnitine
concentration
after
6
weeks
training
(mM
m1
-1
)
Group
Trial
NEC
ASAC
AIAC
CON
pre
47.5
(3.9)
55.4
(3.8)
3.4
(0.8)
post
52.1
(3.1)
60.1
(2.8)
2.4
(0.4)
ET
pre
65.2
(1.8)
68.6
(2.9)
2.2
(0.2)
post
59.2
(2.1)
67.7
(3.6)
1.9
(0.1)
CS
pre
56.3
(3.7)
59.7
(4.4)
2.1
(0.2)
post
68.3
(4.1)
82.4
(7.0)*
2.1
(0.2)
CT
pre
55.2
(2.6)
57.5
(3.7)
2.2
(0.3)
post
74.9
(5.1)*
86.5
(8.1)*
2.7
(0.4)
*Significantly
different
from
pre
values
in
same
experimental
groups
(P
<
0.05)
there
was
no
increase
in
VO
2max
,
a
marker
of
aerobic
capacity
(data
is
not
presented)
as
found
by
Colombani
et
al.
(1996)
and
Trappe
et
al.
(1994).
Most
types
of
exercise
training
reduce
serum
lipid
values,
but
that
was
not
the
case
in
the
present
study
(Fig.
1).
Prolonged
aerobic
exercise
training
decreases
serum
lipid
profiles
(Kim
et
al.
2004;
Cha
et
al.
2003),
but
acute
aerobic
and
anaerobic
exercise
increases
serum
lipids
or
liver
especially
triglycerids
(Jo
et
al.
2004;
Cha
et
al.
2003).
The
percentage
of
type
I
muscle
fibers
in
ET
sub-
jects
increased,
but
remained
unchanged
in
CS.
Type
Ha
muscle
fibers
in
CET
also
increased
at
the
expense
of
decreased
type
IIx
muscle
fibers.
Cross-sectional
areas
of
different
muscle
fiber
types
in
CON,
CS
and
ET
remained
unchanged,
except
in
CET
where
increases
in
type
Ha
and
type
IIx
muscle
fibers
were
observed.
The
present
study
agrees
well
with
the
inves-
tigation
of
Sandra
et
al.
(2002),
which
demonstrated
that
three
months
of
L-carnitine
supplementation
(2
x
2
g
day
-1
)
alone
did
not
induce
any
significant
changes
in
muscle
fiber
composition
and
suggests
that
L-carnitine
supplementation
may
only
bring
about
changes
in
fast
twitch
characteristics
when
combined
with
exercise.
Further,
physical
stress,
such
as
exercise
training,
was
the
major
stimulus
responsible
for
induc-
ing
the
changes
in
muscle
fiber
type
composition
as
seen
in
ET
subjects.
Increased
FA
uptake
and
oxidation
in
trained
mus-
cle
during
endurance
exercise
can
be
induced
by
increased
activity
and
protein
expression
of
FABPc
in
the
cell
membrane
(Kiens
et
al.
1993,
1997;
Turcotte
et
al.
1992).
FABPc
content
is
modulated
by
external
conditions
such
as
training
and
fuel
selection.
Greater
contents
are
more
favorable
to
fast
twitch
characteris-
tics
(Clavel
et
al.
2002).
In
the
present
study,
the
con-
tent
of
FABPc
tended
to
increase
(53%)
following
long-term
exercise
training
although
it
did
not
reach
statistical
significance,
whereas
FABPc
content
was
not
altered
following
carnitine
supplementation.
This
result
indicates
that
exercise
training
exerts
a
more
profound
effect
on
FABPc
content
than
does
L-carni-
tine
supplementation.
Regular
exercise
induces
an
increase
in
activity
of
those
enzymes
involved
either
in
the
tricarboxylic
acid
cycle
or
in
the
0-oxidation
process
(Gollnick
and
Saltin
Springer
198
Eur
J
Appl
Physiol
(2007)
99:193-199
1982).
However,
there
are
contradictory
findings
of
for
example
a
higher
I3-HAD
activity
with
training
(Kiens
et
al.
1993)
but
no
increase
in
other
studies
(Bylund
et
al.
1977;
Schantz
et
al.
1983;
Wibom
et
al.
1992;
Lee
et
al.
2001).
In
the
present
study
no
significant
changes
were
observed
either
with
training
or
canitine
supple-
mentation,
or
a
combination
of
the
two.
In
summary,
L-carnitine
supplementation
may
have
an
effect
on
the
phenotypic
expression
and
size
of
mus-
cle
fiber
types,
which
have
more
glycolytic
characteris-
tics.
When
combined
with
endurance
exercise,
L-
carnitine
supplementation
does
not
appear
to
induce
a
positive
effect
on
fat
metabolism.
Acknowledgements
This
work
was
supported
by
Research
Grant
of
the
Korea
National
Sport
University
and
the
Korea
Re-
search
Foundation
Grant
funded
by
the
Korean
Government
(MOEHRD)
(the
Center
for
Healthcare
Technology
Develop-
ment,
Chonbuk
National
University,
Jeonju,
Korea).
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