COLOCALIZATION OF VASOACTIVE SUBSTANCES IN THE ENDOTHELIAL-CELLS OF HUMAN UMBILICAL VESSELS

Human umbilical vessels are unique in lacking any innervation; thus en dothelial cells may play the major role in local control and regulatio n of the blood flow. In the present study, we examined ultrathin secti ons of cultured human umbilical vein endothelial cells and tissue prep arations of umbilical vein and artery, immunostained by the post-embed ding colloidal gold double-labelling technique. We observed colocaliza tion of atrial natriuretic peptide and neuropeptide Y, as well as colo calization of atrial natriuretic peptide and neuropeptide Y with other vasoactive substances, namely, vasoactive intestinal peptide, substan ce P, calcitonin gene-related peptide and arginine vasopressin. The fu nctional significance of the colocalization of these vasoactive substa nces in the human umbilical vessel endothelial cells is discussed.