DOPAMINE RECEPTOR SUBTYPES IN THE NATIVE HUMAN HEART

The present study first time detected D1-D5 dopamine receptor subtypes in the native human heart simultaneously, found presence of D1, D2, D4, and D5 in cardiac tissues, and revealed distribution features of dopamine receptor subtypes in the epicardium, myocardium, and endocardium. Samples from four native hearts coming from young brain-dead donors, which for technical reason were not used for transplants, were studied. Dopamine receptors were revealed by immunochemistry technique and immunoblot analysis. Morphometrical quantification of the density of each receptor subtype was performed by an image analyzer. Our results demonstrate that only four subtypes of dopamine receptors can be found in cardiac tissues: D1, D2, D4, and D5. These dopamine receptors have been detected in endocardium, myocardium, and epicardium. D1 receptors were stored primarily in the epicardial layer. Dopamine receptors are distributed in the wall of both atria and ventricles, and its transmural gradient can be described in the wall of the human heart. Sections of atria and ventricles exposed to antidopamine receptor antibodies showed fluorescent-positive reaction in the epicardium, myocardium and endocardium. D4 receptor immune reactivity was remarkably less intense than D2 receptor immune reactivity. All the subtypes of dopamine receptors are in close relationships with all cardiac structures. Our findings provide a favorable basis for researching the role of dopamine receptors in controlling functions of the human heart and in the pathogenesis of cardiovascular diseases.