title: Autoradiographic localization of calcitonin gene-related peptide receptors in guinea pig respiratory tract: effect of capsaicin pretreatment.
abstract: Calcitonin gene-related peptide (CGRP) is a potent vasodilator peptide present in capsaicin-sensitive neurons innervating the respiratory tract. In this study, the autoradiographic distribution of [125I]CGRP binding sites was investigated in guinea pig airways. Extremely dense specific binding occurred over parenchymal tissue, with moderate specific binding over tracheal glands, the endothelium of pulmonary veins and arteries, and small blood vessels in the bronchial wall. The localization of binding sites for [125I]CGRP over blood vessels but not bronchial smooth muscle correlates well with the physiological actions of this peptide, although the function of the parenchymal sites is unknown. No significant difference in binding was seen in vehicle- or capsaicin-pretreated animals, suggesting that sites are not reliant on factors from capsaicin-sensitive neurons.
mesh_terms: D000818:Animals; D001345:Autoradiography; D001980:Bronchi / Q000187:drug effects; D002211:Capsaicin / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D008168:Lung / Q000187:drug effects; D008297:Male; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000032:analysis*; D012016:Reference Values; D012137:Respiratory System / Q000737:chemistry / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects
chemical_list: D018015:Receptors, Calcitonin Gene-Related Peptide; D002211:Capsaicin