Angiotensin II (Ang II) and apoptosis contribute significantly to
myocardial ischemia-reperfusion (I-R) injury. Evidence indicates that Ang II may activate apoptosis in myocytes. The present study was undertaken to investigate the effects of
angiotensin receptor blockers (ARBs),
candesartan, on the apoptosis of cardiac myocytes in rats after I-R. Rats were divided into a control group, a
candesartan group I (0.015 mg/kg), and a
candesartan group II (0.03 mg/kg).
Candesartan was intravenously administered 30 min before
ischemia. All rats were subjected to 30 min of
coronary occlusion followed by 3 h of reperfusion. The data showed that left ventricular (LV) systolic pressure and LV +dp/dt was decreased after administration of
candesartan, but increased after reperfusion in the
candesartan group II, compared with those in the
candesartan group I and control group. LV -dp/dt was decreased after
candesartan administration in
candesartan group II. The number of apoptotic cells in the
candesartan groups (497+/-204 and 543+/-254, respectively) was higher than that in the control group (287+/-166; p<0.05). There was no significant difference in
infarct size among the three groups. However, plasma CPK was lower in the
candesartan groups than in the control group. Northern blot analysis showed that p53
mRNA was upregulated in the
candesartan groups, in association with increased expression of bax
mRNA. Immunohistochemical analysis showed that p53 and bax immunoreactivity were increased in both of the
candesartan groups. In conclusion,
candesartan increased apoptosis in the rat hearts after acute I-R, and this increase was possibly mediated by upregulation of p53 and bax gene expressions. In addition,
candesartan was shown to improve LV function, in association with reduction of CPK release.