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Aim. To study the presence and localization of the P2X and P2Y receptor subtypes in the human cystic artery and great saphenous vein (with and without varicose disease).Methods. Segments of the human blood vessels were stained using a standard two-step immunohistochemical analysis using primary and secondary antibodies. In the experiments primary antibodies to the following receptors were used: Р2Х1, Р2Х2, Р2Х3, Р2Х4, Р2Y1, Р2Y2, Р2Y4. In order to determine the presence of a receptor in a vessel sample a comparison was made between staining of the experimental and the control samples, which were not treated with primary antibodies.Results. Immunohistochemical analysis of the cystic artery showed the presence of Р2Х1, Р2Х3, Р2Y1, Р2Y2 receptors. All receptor subtypes were found to be located in the muscular layer of the artery, whereas the P2Y1 receptor was also expressed on the surface of the endothelial cells. In the great saphenous vein without varicose disease Р2Х1, Р2Х2 и Р2Y1 receptor subtypes were identified, all of which were found to be located on the smooth muscle cells of the vein. Similarly to the cystic artery, the Р2Y1 receptor was also found within the endothelial layer of the vein. At the same time, only Р2Х2 и Р2Y1 receptor subtypes were expressed in the muscular layer of the great saphenous vein affected by varicose disease. No P2 receptor subtypes were identified on the endothelial layer of the varicose-diseased vein.Conclusion. Different P2 receptor subtypes were found to be present in the smooth muscle and endothelial layers of the human cystic artery and great saphenous vein. The identified differences in the receptor subtypes between samples of great saphenous veins with and without varicose disease are, most likely, explained by the restructuring of the receptor apparatus as a result of varicose disease progression.

In vitro experiments were carried out to measure the contractile responses to P2-receptor agonists in the greater saphenous vein isolated from patients with obliterating vascular atherosclerosis and varicose veins of the legs. In patients with varicose veins, the contractile responses of the greater saphenous vein to ATP, α,β-methylene-ATP, and UTP were significantly lower than in patients with obliterating atherosclerosis, while the responses to ADP, adenosine, and 2-methylthio-ATP were similar in both groups. These data attest to the presence of P2-receptor-mediated contraction component in the greater saphenous vein, which are pronouncedly weakened during varicose disease.