Page 103 - 79_04

Reduction
in
mitochondrial
membrane
peroxidizability
index…

linked
(glutamate/malate)
and
complex
II-­-linked
(succinate
+
rotenone)

substrates
(Table
1).
No
significant
differences
were
detected
with
both
substrates

in
the
state
4
and
3
between
atenolol
and
control
groups.
However,
the
rate
of

oxygen
consumption
was
higher
in
the
phosphorylating
state
than
in
the
resting

state
with
all
the
substrates
used,
indicating
the
good
functionality
and
tight

coupling
of
the
mitochondria.

Table
1.-­-
Rates
of
oxygen
consumption
of
heart
mitochondria
from
control
or
atenolol
treated

Wistar
rats.

CONTROL

ATENOLOL

60.0±4.8

60.8
±
8.3

Glutamate/malate
(State
4)

Glutamate/malate
(State
3)

203.1±30.4

189.2±11.8

Glutamate/malate
(RCI)

3.5±0.5

3.2±0.3

Succinate+rotenone
(State
4)

135.9±9.4

135.1±11.3

Succinate+rotenone
(State3)

357.3±22.7

364.2±31.9

Succinate+rotenone
(RCI)

2.7±0.1

2.7±0.1

Values
are
means
±
SEM
(nmoles
of
O2/
min
.mg
protein)
from
6-­-8
different
samples
per
group.

State
4:
oxygen
consumption
in
the
absence
of
ADP.
State
3:
oxygen
consumption
in
the
presence
of

500µM
ADP.
RCI:
Respiratory
control
index.

The
mitochondrial
ROS
(mitROS)
generation
rate
showed
a
non-­-significant

trend
to
decrease
in
the
atenolol
group
with
complex
I-­-linked
substrates

(glutamate/malate)
but
not
with
succinate+rotenone
(Table
2).
Maximum
rates
of

ROS
generation
were
assayed
in
the
presence
of
pyruvate/malate+rotenone

(maximum
complex
I
ROS
production)
and
succinate+rotenone+antimycin
A

(maximum
complex
III
ROS
production).
No
significant
differences
between
groups

were
found
either
for
maximum
complex
I
or
complex
III
generation
rates.

Table
2.-­-
Basal
and
maximum
rates
of
ROS
production
of
heart
mitochondria
from
control
or

atenolol
treated
Wistar
rats
in
the
presence
of
different
substrates
and
inhibitors
of
the

mitochondrial
respiratory
chain.

CONTROL

ATENOLOL

Glutamate/malate

0.125±0.02

0.076±0.02

Succinate

1.08±0.24

1.37±0.40

Succinate+rotenone

1.34±0.25

1.43±0.26

Glutamate/malate+rotenone

2.67±0.47

2.98±0.51

Succinate+rotenone+Antimycin
A

7.04±0.85

6.96±0.83

Values
are
means
±
SEM
(nmoles
of
H2O2/
min
mg
protein)
from
6-­-8
different
samples
per
group.

Values
with
glutamate/malate+rotenone
or
succinate+rotenone+antimycin
A
estimate
maximum

mitochondrial
ROS
production
from
complex
I
and
III
respectively.
The
rest
of
the
values
represent

basal
rates
of
ROS
generation
at
complex
I
(with
glutamate/malate
in
forward
and
with
succinate
in

reverse
electron
flow)
or
at
complex
III
(with
succinate,
and
with
succinate+rotenone).

619