Page 100 - 79_04

Alexia
Gómez
&
col.

assembly/maintenance
of
complex
I
(22),
the
respiratory
complex
at
which

mitROS
generation
is
lowered
in
long-­-lived
animals
(23)
as
well
as
in
rats

subjected
to
dietary
restriction
(24).
The
marker
of
oxidative
damage
to

mitochondrial
DNA
(mtDNA)
8-­-oxo-­-7,8-­-dihydro-­-2?-­-deoxyguanosine
(8-­-oxodG)

was
analyzed
by
high-­-performance
liquid
chromatography
(HPLC),
and
five

oxidative
damage
markers
of
protein
oxidation
-­-the
specific
protein
carbonyls

glutamic
and
aminoadipic
semialdehydes
(GSA
and
AASA)
indicating
purely

protein
oxidative
modification,
the
protein
glycoxidation
markers
carboxyethyl

lysine
(CEL)
and
carboxymethyl
lysine
(CML),
and
the
protein
lipoxidation
marker

malondialdehyde
lysine
(MDAL)
were
measured
in
the
rat
heart
by
highly
specific

and
sensitive
mass
spectrometry
techniques.
8-­-oxodG
in
mtDNA
(25)
and
MDA-­-
lysine
(26)
are
known
to
be
correlated
to
longevity
also
and
in
the
correct
sense.

We
also
measured
the
full
fatty
acid
composition
of
heart
mitochondria

membranes
to
calculate
the
global
degree
of
unsaturation,
and
because
protein

lipoxidation
is
secondarily
influenced
by
lipid
peroxidation,
which
strongly

depends
on
membrane
fatty
acid
unsaturation
degree.
Additionally,
we
estimated

the
elongase
and
desaturase
activities
to
determinate
their
role
in
the
acyl
chain

length
and
trying
to
clarify
the
mechanism
responsible
for
putative
changes
in
the

fatty
acid
unsaturation
level
elicited
by
atenolol.

Finally,
in
our
study
we
decided
to
analyze
SIRT3
and
SIRT5
in
order
to

clarify
if
they
could
be
involved
in
the
signaling
mechanisms
resulting
in
the
life-­-
extending
effect
of
ß-­-adrenergic
receptor
blocking.
Sirtuin
proteins
initially

identified
in
lower
organisms
seem
to
be
also
implicated
in
cellular
signaling
of

longevity
extension
in
mammals.
Seven
sirtuins
(SIRT1-­-7)
have
been
described
in

mammals
(27)
and
they
seem
to
have
important
roles
in
aging,
stress
resistance

and
metabolic
regulation.
In
the
present
experiment,
we
have
analyze
SIRT3
and

SIRT5,
due
to
their
localization
at
mitochondria.
Beyond
other
metabolic
actions,

SIRT3
has
been
recently
shown
to
control
the
levels
of
mitROS
by
multiple

mechanisms
,
it
is
induced
by
DR
and
it
has
been
proposed
that
these
increases

lower
the
rate
of
mitROS
production
(28).
SIRT5
is
located
in
the
mitochondrial

matrix
and
intermembrane
space,
and
it
can
deacetylate
cytochrome
c,
a
protein
of

the
mitochondrial
intermembrane
space
with
a
central
function
in
oxidative

metabolism,
as
well
as
apoptosis
(29).
Most
of
the
parameters
measured
in
this

investigation
have
not
been
assayed
in
the
AC5KO
longevity-­-extended
model.

Therefore,
the
present
study
can
contribute
to
clarify
whether
mitochondrial
or

membrane
oxidative
stress
is
involved
in
the
mechanism
responsible
for
the

increased
life
span
elicited
by
ß-­-adrenergic
blockade.

616