Effect of amrinone on portal hemodynamics and tissue blood flow in the isolated perfused rat liver.

We studied the effect of amrinone on portal perfusion pressure, perfusion flow, and tissue blood flow using an isolated perfused rat liver model. In the constant perfusion flow model, amrinone effectively decreased perfusion pressure in the precontracted state by adenosine triphosphate (ATP) or norepinephrine. Amrinone dose-dependently decreased portal perfusion pressure increased by calcium chloride. Similarly, amrinone dose-dependently increased portal perfusion flow decreased by ATP in the constant perfusion pressure model. Amrinone effectively increased tissue blood flow decreased by ATP or norepinephrine measured by laser-Doppler flowmetry. A specific inhibitor of the biosynthesis of nitric oxide, N omega-nitro-L-arginine, did not affect the hemodynamic effect of amrinone, suggesting that nitric oxide is not involved in the portal vasodilating effect of amrinone. We conclude that amrinone increases portal blood flow by decreasing perfusion pressure and contributes to increasing tissue blood flow of the liver without the involvement of nitric oxide.