H. Sonoki et al., NIPRADILOL, A NEW BETA-ADRENERGIC BLOCKER, REDUCES LEFT-VENTRICULAR REMODELING FOLLOWING MYOCARDIAL-INFARCTION IN SPONTANEOUSLY HYPERTENSIVE RATS, Heart and vessels, 12(1), 1997, pp. 19-26
Left ventricular (LV) cavity dilation (remodeling) following myocardia
l infarction (MI) is a risk factor for morbidity and mortality. This s
tudy was undertaken to determine whether nipradilol, a new beta-adrene
rgic blocker with vasodilating action, reduces LV remodeling after MI
produced by coronary ligation in spontaneously hypertensive rats. The
effects on LV remodeling of the following drugs, which were administer
ed orally for 4 weeks, were evaluated by assessing LV end-diastolic vo
lume index (LVEDVI): (1) vehicle, (2) nipradilol, 10 mg/kg per day, (3
) propranolol, 50 mg/kg per day, and (4) captopril, 30 mg/kg per day.
Since LVEDVI depends on infarct size, the effects of the drugs on LVED
VI were compared between rats with a similar infarct size, i.e., moder
ate, 20%-40%; and large, 40%-60%, on the basis of the histological det
ermination of infarct size. The nipradilol-treated and captopril-treat
ed rats had significantly smaller LVEDVI than did the vehicle-treated
rats with both moderate and large infarction (large infarct: 2.48 +/-
0.12 ml/kg for the vehicle group, 1.69 +/- 0.10 ml/kg for the nipradil
ol group, P < 0.01, and 1.79 +/- 0.14 ml/kg for the captopril group, P
< 0.01). In contrast, LVEDVI in the propranolol-treated rats was sign
ificantly greater than that in the vehicle-treated rats with a moderat
e infarct (2.09 +/- 0.09 ml/kg for the vehicle group versus 2.44 +/- 0
.10 ml/kg for the propranolol group, P < 0.05). The results indicate t
hat nipradilol and captopril reduce LV remodeling after MI, whereas pr
opranolol promotes it.