Effects of
azelnidipine were examined and compared with those of
amlodipine on
stunned myocardium in dogs. The left anterior descending (LAD) coronary artery was ligated for 20 min and subsequently released for 60 min. A vehicle,
azelnidipine (0.3 mg/kg), or
amlodipine (0.3 or 1 mg/kg) was injected intravenously 20 min before LAD
ligation. The heart rate increased after a depressor response in the presence of
amlodipine, while it decreased despite a decrease in arterial pressures in the presence of
azelnidipine. After reperfusion, the coronary flow (CF) significantly increased in the presence of
azelnidipine, but did not change with
amlodipine after reperfusion. A positive inotropic effect was observed
after treatment with both
calcium antagonists.
Ischemia significantly decreased the percentage of segment shortening (%SS) in all groups. Treatment with both
calcium antagonists significantly increased %SS after reperfusion, although high-energy
phosphate levels did not improve in the presence of
calcium antagonists 60 min after reperfusion. Mortality with
azelnidipine was significantly lower than that with 0.3 mg/kg
amlodipine immediately after reperfusion. In conclusion, improvement in
myocardial stunning after pretreatment with
azelnidipine is associated with an increase in CF after reperfusion. The negative chronotropic action may have contributed to decreased mortality due to reperfusion arrhythmias.
Azelnidipine is more beneficial than
amlodipine and may provide an additional advantage to patients with angina and
hypertension.