title: Spatio-temporal aspects, pathways and actions of Ca(2+) in surfactant secreting pulmonary alveolar type II pneumocytes.
abstract: The type II cell of the pulmonary alveolus is a polarized epithelial cell that secretes surfactant into the alveolar space by regulated exocytosis of lamellar bodies (LBs). This process consists of multiple sequential steps and is correlated to elevations of the cytoplasmic Ca(2+) concentration ([Ca(2+)](c)) required for extended periods of secretory activity. Both chemical (purinergic) and mechanical (cell stretch or exposure to an air-liquid interface) stimuli give rise to complex Ca(2+) signals (such as Ca(2+) peaks, spikes and plateaus) that differ in shape, origin and spatio-temporal behavior. This review summarizes current knowledge about Ca(2+) channels, including vesicular P2X4 purinoceptors, in type II cells and associated signaling cascades within the alveolar microenvironment, and relates stimulus-dependent activation of these pathways with distinct stages of surfactant secretion, including pre- and postfusion stages of LB exocytosis.
authors.affiliation: Institute of General Physiology, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany. paul.dietl@uni-ulm.de
authors.forename: Paul
authors.initials: P
authors.lastname: Dietl
authors.forename: Thomas
authors.initials: T
authors.lastname: Haller
authors.forename: Manfred
authors.initials: M
authors.lastname: Frick
mesh_terms: D056809:Alveolar Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D005089:Exocytosis / Q000502:physiology; D006801:Humans; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism; D058848:Receptors, Purinergic P2X4 / Q000378:metabolism; D013501:Surface-Active Agents / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D058848:Receptors, Purinergic P2X4; D013501:Surface-Active Agents; D002118:Calcium