Effects of amrinone on renal blood flow and cardiac function, in comparison with those of milrinone and olprinone, in anesthetized dog

Amrinone, one of the phosphodiesterase III inhibitors, is clinically used for acute heart failure and possesses diuretic action, which is not observed in other phosphodiesterase III inhibitors. To clarify the mechanism of the diuretic action of amrinone, we investigated its effects on renal blood flow and some other hemodynamic parameters in comparison with the effects of milrinone and olprinone in anesthetized dogs. Amrinone increased both renal and femoral blood flow in a dose-dependent manner. On the other hand, milrinone and olprinone increased only femoral blood flow and had no effect on renal blood flow. Amrinone, milrinone and olprinone dose-dependently increased left ventricular max dp/dt, and the estimated slope of the dose-response curve for olprinone was significantly sharper than that of amrinone. Furthermore, these three drugs increased the cardiac index and decreased systemic vascular resistance (SVR) significantly. The action of amrinone on SVR was more potent than those of milrinone and olprinone. These results suggest that the diuretic action of amrinone is involved in augmentation of renal blood flow and may support useful effects on acute heart failure.