Dopamine receptor subtypes in the human coronary vessels of healthy subjects

Abstract

Objective: Dopamine D₁–D₅ receptors subtypes were studied in human coronary vessels of healthy subjects to assess their localization and their expression.

Methods: Samples of intraparenchymal and extraparenchymal branches of human coronary arteries and veins were harvested from four normal native hearts explanted from four young brain dead heart donors in case of orthoptic transplant, not carried out for technical reasons. In all the samples morphological, biochemical, immunochemical, and morphometrical studies were performed including quantitative analysis of images and evaluation of data.

Results: Microanatomical section showed healthy coronary vessels, which expressed all dopamine receptors (from D₁ to D₅) with a different pattern of distribution between the different layers, in the intra and in the extraparenchymal branches.D₁ and D₅ (with a prevalence D₁ over D₅) were distributed in the adventitia and to a lesser extent in the outer media but they were absent in arterioles, capillaries and venules. Endothelial and the middle layer showed D₂, D₃ and D₄ receptors, with a greater expression of D₂. Immunoblot analysis of dopamine monoclonal antibodies and dopamine receptors showed a different migration band for each receptor: D₁ (45 KDa); D₂ (43 KDa); D₃ (42 kDa); D₄ (40–42 KDa); D₅ (38–40 KDa)

Conclusion: These findings demonstrate the presence of all dopamine receptor subtypes in the wall of human coronary vessels of healthy subjects. Dopamine D₁ and D₂ receptor subtypes are the most expressed, suggesting their prominent role in the coronary vasoactivity.

Keywords::

• Dopamine
• receptor
• coronary
• humans
• immunohistochemistry