Amrinone, a new cardiotonic drug, has received attention as a better t
herapeutic agent than the cardiac glycosides in the treatment of conge
stive heart failure. In this study, the effects of amrinone on isolate
d rat uterus and its probable mechanism of action were investigated. A
t two different concentrations (0.1 and 0.5 mM), the inhibitory effect
s of amrinone on the spontaneous contractions of rat uterus were noted
. In addition, amrinone (0.5 mM) was found to inhibit the tonic contra
ctions induced by potassium sulphate (K2SO4)-Ringer solution (91.74%)
and calcium chloride (CaCl2) (93.04%). These inhibitory effects were c
ompared with regulators of the phosphodiesterase enzyme (PDE). It was
concluded that amrinone could behave as a calcium antagonist and PDE i
nhibitor.