Endothelial cell receptors for histamine

TLDR: Biological active, electron-opaque conjugates of histamine and its agonists are produced, which are recently used to localize in situ the histamine receptors on the vascular endothelium.

Abstract: The physiological activities of histamine on various systems including the heart and blood vessels'-9 are mediated by at least two different types of receptors.10-12 As defined on a pharmacological basis, the H1 receptors are specifically inhibited by classical antihistamines such as mepyramine, and have as agonists drugs such as 2-pyridylethylamine, The Hz receptors are blocked by antagonists such as cimetidine, and have as a specific agonist 4-methylhistamine.4~~~~~~~~~~~4 The identification of histamine receptors and their subclasses on diverse cells, including those of the cardiovascular system, has relied primarily on the target responses to histamine and its specific agonists and antagonists.15-26 It has been demonstrated that histamine receptors are located on the plasma membrane of several mammalian cells.27-33 Their presence was so far detected either indirectly, by the binding of various cells to histamine insolubilized on agarose beads,z7.34.35 or visualized at the light microscope level by coupling histamine to bovine serum albumin-fluoresceine isothiocyanatezz or to o-phthaldialdehyde.36 Another indirect way of identifying histamine receptors was by measuring the binding of the antagonist [3H]mepyramine.37 However, the direct detection and the topographical distribution of histamine receptors and their subclasses at the ultrastructural level have not been accomplished yet. We have carried out studies with the electron microscope to localize histamine receptors in various cells of the vessel wall. For this purpose, we have produced biologically active, electron-opaque conjugates of histamine and its agonists, which we have recently used to localize in situ the histamine receptors on the vascular endothelium.38-40