Calcium and ionophore A23187 lower calcitonin gene-related peptide-like immunoreactivity in endocrine cells of organ cultured fetal rat lungs.
Small-granule endocrine cells differentiate in airway epithelium of intact and cultured fetal rat lungs. We noted that the cells store calcitonin gene-related peptide (CGRP) in vitro as well as in vivo and used the ionophore A23187 to test the effects of calcium on peptide secretion in this system. Lungs of 14-day and 15-day fetal rats, organ cultured for 6-9 days, were divided into groups of 5 explants each and incubated for 15 min at 37 degrees C in the basic medium containing 0 mM, 1 mM, or 10 mM CaCl2, with or without 8 microM A23187, or 10 mM EGTA. Intracellular CGRP in these explants was quantified by supraoptimal dilution peroxidase immunocytochemistry (Springall et al.: J. Pathol. 155:259-267, 1988): counts were made of endocrine cells stained with a 1/60,000 dilution of anti-CGRP and repeated on the same sections after restaining with antibody diluted at 1/1,000. Results, analyzed by Chi-square test, were expressed as % cells stained with antibody at 1/60,000 vs. those stained at 1/1,000. Immunoreactivity for CGRP was significantly reduced by A23187 in the presence of high extracellular Ca2+ (10 mM), the inference being that these cells secrete peptide hormones in response to Ca2+ influx across the plasma membrane. The organ cultures evidently can be used to assess certain physiological responses of lung endocrine cells in an accessible, relatively organotypical setting.
Department of Anatomy and Neurobiology, Boston University School of Medicine, MA 02118.
M
M
Ebina
R F
RF
Hoyt
S P
SP
Sorokin
N A
NA
McNelly
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D015740:Calcitonin Gene-Related Peptide / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D005333:Fetus; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009490:Neurosecretory Systems / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley
D000001:Calcimycin; D015740:Calcitonin Gene-Related Peptide; D002118:Calcium