Oxidative/nitrative stress caused by
peroxynitrite, the reaction product of
superoxide (O2(.-)) and
nitric oxide (NO), is the primary cause of
myocardial ischemia/
reperfusion injury. The present study determined whether
INO-4885 [5,10,15,20-tetra[N-(benzyl-4'-carboxylate)-2-pyridinium]-21H,23H-
porphine iron(III)
chloride], a new
peroxynitrite decomposition catalyst, may provide cellular protection and protect heart from
myocardial ischemia/
reperfusion injury. Adult male mice were subjected to 30 min of
ischemia and 3 or 24 h of reperfusion. Mice were randomized to receive vehicle,
INO-4885 without catalytic moiety, or
INO-4885 (3-300 microg/kg i.p.) 10 min before reperfusion.
Infarct size, apoptosis,
nitrotyrosine content, NO/O2(.-) production, and
inducible nitric-oxide synthase (iNOS)/
NADPH oxidase expression were determined.
INO-4885 treatment reduced
ischemia/reperfusion-induced
protein nitration and
caspase 3 activation in a dose-dependent fashion in the range of 3 to 100 microg/kg. However, doses exceeding 100 microg/kg produced nonspecific effects and attenuated its protective ability. At the optimal dose (30 microg/kg),
INO-4885 significantly reduced
infarct size (p < 0.01), decreased apoptosis (p < 0.01), and reduced tissue
nitrotyrosine content (p < 0.01). As expected,
INO-4885 had no effect on
ischemia/reperfusion-induced iNOS expression and NO overproduction. To our surprise, this compound significantly reduced
superoxide production and partially blocked
NADPH oxidase overexpression in the ischemic/reperfused cardiac tissue. Additional experiments demonstrated that
INO-4885 provided better cardioprotection than
N-(3-(aminomethyl)benzyl)acetamidine (1400W, a selective iNOS inhibitor),
apocynin (an
NADPH oxidase inhibitor), or
Tiron (a cell-permeable
superoxide scavenger). Taken together, our data demonstrated that
INO-4885 is a cardioprotective molecule that attenuates
myocardial reperfusion injury by facilitating
peroxynitrite decomposition and inhibiting
NADPH oxidase-derived O2(.-) production.