title: InsP3 receptor type 2 and oscillatory and monophasic Ca2+ transients in rat adrenal chromaffin cells.
abstract: Muscarinic receptor stimulation induced oscillatory and monophasic Ca(2+) transients in rat adrenal chromaffin cells in the absence of external Ca(2+). As this Ca(2+) mobilization may be mediated by InsP(3), we first explored types of InsP(3) receptors and their intracellular distribution in chromaffin cells. The InsP(3) receptor type 1 was not immunodetected in precipitates of adrenal medulla homogenates and in dissociated adrenal chromaffin cells, whereas an anti-type 3 mAb recognized a faint band with about 250 kDa, but no significant immunoreaction was visible in chromaffin cells. The anti-type 2 mAb strongly detected a band with about 220 kDa and the immunoreaction was observed perinuclearly and at the cell periphery. These results indicate that InsP(3) receptor type 2 is predominant in chromaffin cells. The oscillatory and monophasic Ca(2+) transients were reproduced in simulation based on a three-state kinetic model (shut, open, and inactivated states). Ca(2+) ions were found experimentally and theoretically to turn over rapidly between stores and the cytosol during stimulation. The results suggest that InsP(3) receptor type 2 is responsible for both oscillatory and monophasic Ca(2+) transients and that change in mode of Ca(2+) responses may be accounted for by the kinetic property of the type 2 receptor.
authors.affiliation: Department of Cell and System Physiology, University of Occupational and Environmental Health School of Medicine, Kitakyushu 807 8555, Japan. minoue@med.uoeh-u.ac.jp
authors.forename: Masumi
authors.initials: M
authors.lastname: Inoue
authors.forename: Hai
authors.initials: H
authors.lastname: lin
authors.forename: Issei
authors.initials: I
authors.lastname: Imanaga
authors.forename: Koichi
authors.initials: K
authors.lastname: Ogawa
authors.forename: Akira
authors.initials: A
authors.lastname: Warashina
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000032:analysis / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D019439:Chromaffin Cells / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015151:Immunoblotting; D007150:Immunohistochemistry; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007700:Kinetics; D008954:Models, Biological; D009116:Muscarine / Q000494:pharmacology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis / Q000502:physiology*; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D019284:Thapsigargin; D009116:Muscarine; D002118:Calcium