Beta-adrenergic receptors in human trabecular meshwork. Identification and autoradiographic localization.
Beta-adrenergic receptors were identified in slide-mounted sections of human trabecular meshwork by in-vitro labeling, light microscopic autoradiography. Autoradiograms were generated after incubation of slide-mounted tissue sections with 125I-cyanopindolol, a selective high-affinity probe for beta-adrenergic receptors. Experiments in which an excess of either unlabeled Practolol (beta 1 selective ligand) or Zinterol (beta 2 selective ligand) were included suggested that most of the receptors were of the beta 2 subtype. Data from displacement studies using increasing concentrations of the highly specific beta 1- and beta 2-adrenergic receptor antagonists, ICI-89,406 and ICI-118,551, respectively, confirmed the predominance of the beta 2-adrenergic receptors. Similar results obtained with cultured trabecular endothelial cells suggest that the beta-adrenergic receptors may be associated with the endothelial cells of the trabecular meshwork in vivo. These results provide anatomic evidence for the hypothesis that beta-adrenergic agents improve outflow by direct action on the trabecular meshwork and provide a rationale for the development of more selective beta 2-adrenergic agents to increase outflow facility.
D001345:Autoradiography; D002478:Cells, Cultured; D004727:Endothelium / Q000166:cytology; D004983:Ethanolamines / Q000378:metabolism; D006801:Humans; D020120:Iodocyanopindolol; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011217:Practolol / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000032:analysis* / Q000378:metabolism; D014129:Trabecular Meshwork / Q000032:analysis* / Q000166:cytology
D004983:Ethanolamines; D011943:Receptors, Adrenergic, beta; C002904:zinterol; D020120:Iodocyanopindolol; D010869:Pindolol; D011217:Practolol