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.
Ebina
M
M
Department of Anatomy and Neurobiology, Boston University School of Medicine, MA 02118.
Hoyt
R F
RF
Sorokin
S P
SP
McNelly
N A
NA
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