Effect of sigma receptor ligand haloperidol on guinea pig isolated heart electrogram

Cardiac sigma receptors are involved in fine modulation of contractility in mammalian myocardium. Their role in the changes of cardiac excitability is studied using various experimental models. In this study, the effect of sigma receptor ligand, psychotropic drug haloperidol, was examined in isolated guinea pig hearts perfused according to Langendorff. Electrogram and coronary flow changes were followed in control and during two administrations of haloperidol. Prolongation of QT interval was found in the first, but not in the second haloperidol application. It is concluded, that sigma ligand haloperidol affects repolarization phase of cardiac electrogram and this process may explain various rhythm disturbances reported in patients treated with haloperidol.