Endocardial Endothelium Modulates Inotropic Responses of Subjacent Myocardium

In contrast to vascular endothelium, the functional role of endocardial endothelium has been largely underestimated. It was now been demonstrated that selective removal of the endocardial endothelium from isolated heart muscle preparations resulted in reduction of twitch duration and peak twitch tension, but did not significantly alter maximal unloaded velocity of shortening (V max ). Alternatively, the presence of an intact endocardial endothelium increased peak twitch tension mainly by prolonging twitch duration.