Istaroxime hydrochloride acting as a positive inotropic compound through the inhibition of the Na
+
,K
+
-ATPase. Istaroxime (PST2744) inhibits the Na
+
/K
+
-ATPase activity from dog kidney with an IC
50
value of 0.43 ± 0.15 μM. Inhibition of Na
+
/K
+
-ATPase activity in preparations from guinea pig kidney yielded potencies of 8.5 μM for PST2744.
Istaroxime (PST2744) induces a progressive increase in +dP/dt
max
throughout the infusion that reaches 80% (ED
80
) at the cumulative dose of 1.89±0.37 mg/kg and a peak of 140±3.5% at the dose (ED
max
) of 4.88±0.6 mg/kg.
