title: Increased intracellular levels of calcitonin gene-related peptide-like immunoreactivity in pulmonary endocrine cells of hypoxic rats.
abstract: The mammalian respiratory tract contains innervated groups of endocrine cells which are believed to respond to hypoxia. We have demonstrated the involvement of a specific regulatory peptide produced by the cells, calcitonin gene-related peptide (CGRP), in this response. Cells immunoreactive for CGRP or for protein gene product 9.5 (PGP 9.5), a general marker of nerves and endocrine cells, were quantified in sections of lungs from hypoxic (21 days, 10 per cent O2) and normoxic rats. An immunostaining method employing supra-optimal dilutions of primary antiserum was used. This detects variations in antigen concentration which may be masked if the routine, optimal dilution is used. The number of CGRP-immunoreactive endocrine cells was significantly (P less than 0.001) greater in the lungs of hypoxic rats (76.9 +/- 10.1 cells/cm2, mean +/- SEM) compared with controls (19.7 +/- 2.4). However, the numbers of PGP 9.5-immunoreactive cells were the same in both groups (81.3 +/- 12.2, hypoxic; 79.5 +/- 9.8 control), suggesting that the total number of endocrine cells did not change. It is concluded therefore that the apparent increase in CGRP-immunoreactive endocrine cells in hypoxic rat lungs is due to increased intracellular levels of the peptide. Since CGRP is a vasodilator, this could have important implications in the vasoconstrictor response to hypoxia.
mesh_terms: D001078:APUD Cells / Q000378:metabolism*; D000818:Animals; D000941:Antigens / Q000032:analysis; D002116:Calcitonin / Q000378:metabolism*; D015740:Calcitonin Gene-Related Peptide; D000860:Hypoxia / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009479:Neuropeptides / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D043222:Ubiquitin Thiolesterase
chemical_list: D000941:Antigens; D009479:Neuropeptides; D002116:Calcitonin; D043222:Ubiquitin Thiolesterase; D015740:Calcitonin Gene-Related Peptide