title: Calcium binding sites in the vesicles of the carotid and aortic body chief cells.
abstract: Chief cells of the carotid and aortic body chemoreceptors possess numerous cytoplasmic dense-core vesicles which are known to contain primarily dopamine. Following fixation in solutions containing 50 mM CaCl2, a 20--30 nm electron-dense particle (EDP) is often observed eccentrically located in many of the vesicles. Approximately 44% of the carotid body and 16% of the aortic body vesicles contain an EDP. The EDP probably represents the Ca++ binding site critical to the stimulus-secretion coupling events culminating in exocytosis of these vesicles. The presence of Ca++ in the cytoplasmic vesicles was verified by electron probe X-ray microanalysis.
mesh_terms: D000818:Animals; D001016:Aortic Bodies / Q000378:metabolism* / Q000648:ultrastructure; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002344:Carotid Body / Q000378:metabolism* / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000378:metabolism; D004577:Electron Probe Microanalysis; D008297:Male; D010234:Paraganglia, Nonchromaffin / Q000378:metabolism*; D011817:Rabbits
chemical_list: D002118:Calcium