Effects of milrinone on contractility and cyclic adenosine monophosphate production induced by beta1- and beta2-adrenergic receptor activation in human myocardium.

Background: Because milrinone is a widely used phosphodiesterase-3 (PDE3) inhibitor, it would be of interest to know whether it interacts with beta1- and beta2-adrenergic receptor (AR) agonists in human myocardium.

Objectives: This in vitro study was conducted to test whether milrinone differentially regulates cyclic adenosine-3',5'-monophosphate (cAMP) production and to examine the effect of milrinone on the positive inotropic responses and cAMP production induced by activation of the beta1-AR with norepinephrine (NE) and activation of the beta2-AR with epinephrine (EPI) in human atrial myocardium.

Methods: Right atrial trabeculae were obtained from patients undergoing cardiac surgery for valve repair.