Increased
monoamIne oxIdase actIvIty of lung wIth IschemIa-reperfusIon
Injury: effect of precondItIonIng
Gülberk UÇAR*,o,
Eda TOPALOĞLU*, H. Burak KANDİLCİ**, Bülent GÜMÜŞEL**
*Hacettepe University, Faculty of Pharmacy, Depatment of
Biochemistry, 06100 Sıhhiye, Ankara, TURKEY. **Hacettepe
University, Faculty of Pharmacy, Depatment of Pharmacology,
06100 Sıhhiye, Ankara, TURKEY.
oCorresponding Author
Summary
Recent studies have been focused on the protective role
of ischemic preconditioning (IP) against ischemia reperfusion
(I/R) injury of the lung occurring following cardiopulmonary
bypass or lung transplantation. Although reactive oxygen
species (ROS) production has been postulated to play a crucial
role in I/R, the sources of ROS during I/R are still unclear.
Since it has been previously described that monoamine oxidases
(MAOs) are a potential source of hydrogen peroxide (H2O2)
generation in early reperfusion following ischemia, the
present study aimed to investigate the possible contribution
of MAO to ROS generation and lipid peroxidation during I/R
and IP protocols in the lung. Male Wistar rats were randomly
divided into three groups: control lungs were subjected
to 30 min. of perfusion; lungs of the I/R group were subjected
to 2 h of cold ischemia following 30 min. of perfusion;
and in the third group IP was performed by two cycles of
5 min. ischemia followed by 5 min. of reperfusion prior
to 2 h of cold ischemia and then reperfusion. MAO-A and
B activities, lipid peroxidation, reduced (GSH) and oxidized
(GSSG) glutathione levels, H2O2 release and catalase activity
were determined in tissue samples. MAO-A and B activities,
lipid peroxidation, GSSG content and H2O2 release were found
to be increased, while GSH content, GSH/GSSG ratio and catalase
activity were decreased in lung tissues of the I/R group
when compared with those of the control group. MAO-A and
B activities, lipid peroxidation, GSSG content and H2O2
release were found to be decreased, while GSH content, GSH/GSSG
ratio and catalase activity were increased in lung tissues
of the IP group when compared with those of the I/R group.
Strong positive correlations were foundbetween MAO activity
and H2O2 release in lung tissues of I/R and IP groups, suggesting
that MAO is a potential source of H2O2 generation during
reperfusion and that IP protects the lung against oxidative
damage via diminishing MAO-mediated excess H2O2 formation.
Although the present study is preliminary by design, we
suggest that MAO isoforms may contribute to ROS generation
during I/R, and that MAO inhibitors may be used together
with IP to protect against lung injury during I/R.
Key Words :
Preconditioning, ischemia-reperfusion, monoamine oxidase. |
