Polyamines (
putrescine,
spermidine, and
spermine) are present in all higher eukaryotic cells and are essential for cell growth, differentiation and apoptosis. Sharing common precursor with
polyamines,
nitric oxide (NO) is associated with
myocardial ischemia/
reperfusion injury by the generation of
peroxynitrite. Although
polyamines have been implicated in tissue
ischemia injury, their metabolism and interactions with NO in
myocardial ischemia/
reperfusion injury have not been fully understood. In our experiment, when Langendorff perfused rat hearts were subjected to 40 min
ischemia without reperfusion, both
ornithine decarboxylase (ODC) and
Spermidine/spermine N(1)-acetyltransferase (SSAT) activities were up-regulated and
putrescine accumulated. While after reperfusion, ODC activity decreased and SSAT activity increased, resulting in
putrescine accumulation and decreased
spermidine and
spermine. Meanwhile NO content was increased. In addition,
sodium nitroprusside (SNP, a NO donor) decreased ODC activity in cardiac tissue homogenate but increased SSAT activity in a dose-dependent manner. Pre-treatment of isolated heart with
N(omega)-nitro-L-arginine methyl ester hydrochloride (
L-NAME, an inhibitor of
NO synthase) increased ODC activity. Exogenous
spermine (1 mM) administration prior to
ischemia prevented
spermine decrease, reduced cardiac myocyte
necrosis and apoptosis, and promoted the recovery of cardiac function after
ischemia/reperfusion. These results suggest that acute heart
ischemia activates myocardial
polyamine stress response characterized by increased ODC and SSAT activities and accumulation of
putrescine.
Ischemia/reperfusion disturbs
polyamine metabolism, and the loss of
spermine might be associated with NO increase and thereby influences myocardial cell viability. Exogenous
spermine may protect the hearts from
myocardial ischemia/
reperfusion injury.