Our previous study has shown that the concentrations of
norepinephrine,
epinephrine and
dopamine in the plasma of BIO 53.58 hamsters (a model of
dilated cardiomyopathy: DCM) at 18 weeks of age (severe cardiomyopathic stage) were twice those of age-matched F1B control and conversely the myocardial
norepinephrine level was decreased. The present study was undertaken to examine the effect of
amlodipine on
catecholamine concentration, myocardial receptors and histopathological changes in BIO 53.58 hamsters.
Oral administration of
amlodipine (10 mg/kg/day) for 7 weeks in 11 week-old-BIO 53.58 hamsters brought about marked decreases in the concentrations of
norepinephrine,
epinephrine and
dopamine in the plasma, compared with those in vehicle-treated BIO 53.58 hamsters. This was accompanied by a concomitant increase in the concentration of myocardial
catecholamine concentration. In other words, the concentrations of
catecholamines in plasma and myocardium of
amlodipine administered BIO 53.58 hamsters approximated to the control level in age-matched F1B. In addition,
amlodipine administration caused a significant reduction of
calcium deposition with a tendency toward a decrease in the myocardial
necrosis, and it had little effect on the affinity and number of specific binding for (+)-[3H]
PN 200-110, (-)-[125I]
iodocyanopindolol (CYP) and [3H]
prazosin in the myocardium. In conclusion, the present study shows that administration of
amlodipine in BIO 53.58 hamsters may exhibit ameliorating effect on plasma and myocardial
catecholamines with a significant reduction of
calcium deposition. These data may offer further support for the use of
amlodipine in patients with DCM.