Alexia Gómez & col.
620
The free radical leak (FRL; the percentage of total electron flow in the
respiratory chain directed to ROS generation) values of heart mitochondria did not
show significant differences between the control and the atenolol group either
with pyruvate/malate or succinate+rotenone as substrates (Table 3). Oxidative
damage to mtDNA was estimated by measuring the amount of 8-‐oxodG referred to
the amount of the non-‐oxidized deoxynucleoside (dG) (Table 3). In agreement with
the lack of changes in FRL% and mitROS production, we did not observe significant
differences in 8-‐oxodG between the control and the atenolol group.
Table 3.-‐
Free radical leak (FRL%) at the mitochondrial respiratory chain and oxidative damage to
mitochondrial DNA of heart mitochondria from control or atenolol treated Wistar rats.
CONTROL
ATENOLOL
FRL % (glutamate/malate)
0.11±0.03
0.06±0.01
FRL % (succinate+rotenone)
0.56±0.13
0.58±0.10
8-‐oxodG in mtDNA
6.46±1.07
8.65±1.25
Values are means ± SEM (nmoles of H
2
O
2
/ min
.
mg protein) from 6-‐8 different samples per group. The
FRL% is the percentage of the total electron flow in the respiratory chain directed to oxygen radical
generation (see Materials and Methods for further details). It represents the efficiency of the
mitochondria avoiding the univalent lateral leak of electrons out of the respiratory chain that
generates ROS. The lower the FRL%, the higher such efficiency. 8-‐oxodG is a marker of steady-‐state
oxidative damage to mtDNA and is expressed as 8-‐oxodG/10
5
dG.
The amounts of the two complex I subunits (NDUFS3 and NDUFA9),
complex II, III and IV were measured, as well as AIF (apoptosis inducing factor),
SOD2 (superoxide dismutase), SIRT3 and SIRT5 (Figure 1). The NDUFA9 complex I
subunit and MnSOD were significantly lower in the atenolol group. The other
parameters did not show significant differences between experimental groups.
The markers of protein glycoxidation CEL and CML were significantly
higher in the atenolol group (Figure 2). On the other hand, the lipoxidation-‐
dependent marker of protein modification MDAL was significantly lower in
atenolol treated animals, and the specific protein carbonyls GSA and AASA did not
show significant differences (Figure 2).
