title: Calcium distribution and mobilization in single rat parotid acinar cells investigated by digital imaging microscopy.
abstract: The intracellular distribution and mobilization of cytosolic free calcium in single rat parotid acinar cells was analyzed by a digital imaging microscope equipped with a microspectrofluorometer, using calcium-sensitive dye fura-2. In the resting state, intracellular distribution of cytosolic free calcium concentration ([Ca2+]i) was heterogeneous: [Ca2+]i in the nuclear and perinuclear region was usually higher than that in the cytoplasm. By Ca(2+)-ionophore ionomycin and muscarinic agonist carbachol stimulation in the presence of 1 mM extracellular Ca2+, [Ca2+]i increased markedly and the gradient of [Ca2+]i between the nuclear region and the cytoplasm decreased. In ionomycin stimulation, [Ca2+]i increased homogeneously and this homogeneous increase was irreversible. In carbachol stimulation the gradient of [Ca2+]i between the nuclear region and the cytoplasm obviously reappeared within 2 min. By carbachol stimulation in the absence of extracellular Ca2+ (added 1 mM EGTA), [Ca2+]i returned to the prestimulation level after the initial transient increase. The distribution of [Ca2+]i also returned approximately to the prestimulation state. The gradient of [Ca2+]i between the nuclear region and the cytoplasm did not disappear even when [Ca2+]i elevated at the peak value.
authors.affiliation: Department of Otolaryngology, Kansai Medical University, Moriguchi, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Harada
authors.forename: T
authors.initials: T
authors.lastname: Yamashita
authors.forename: H
authors.initials: H
authors.lastname: Amano
authors.forename: N
authors.initials: N
authors.lastname: Maeda
authors.forename: T
authors.initials: T
authors.lastname: Kumazawa
authors.forename: Y
authors.initials: Y
authors.lastname: Tashiro
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002467:Cell Nucleus / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D008853:Microscopy; D008856:Microscopy, Fluorescence; D015591:Microspectrophotometry; D010306:Parotid Gland / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D015759:Ionomycin; D002217:Carbachol; D002118:Calcium