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Visualization of the effects of acute hypoxia on the intracellular free calcium concentration ([Ca 2+ ] i ) of pulmonary neuroepithelial bodies (NEBs) in an in situ lung slice model
Author(s) -
De Proost Ian,
Pintelon Isabel,
Brouns Inge,
Riccardi Daniela,
Kemp Paul J,
Timmermans JeanPierre,
Adriaensen Dirk
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a925-b
Subject(s) - hypoxia (environmental) , extracellular , chemistry , microbiology and biotechnology , intracellular , biophysics , membrane potential , lung , medicine , biology , oxygen , organic chemistry
For many years now, hypoxia is considered as an important stimulus for NEBs. Acute hypoxia has been suggested to close background K + channels, resulting in membrane depolarisation and influx of Ca 2+ via voltage‐gated Ca 2+ channels, eventually triggering exocytosis of neurotransmitters from NEB cells. Our lab recently established an in situ live cell imaging model based on vibratome slices of live mouse lungs that allows visualization of pulmonary NEBs and simultaneous monitoring of the [Ca 2+ ] i using Fluo‐4. Aim was to study the effect of acute hypoxia on the [Ca 2+ ] i of NEB cells. Acute hypoxia, applied by saturating the solution with N 2 , or by adding Na 2 S 2 O 4 to scavenge O 2 , never resulted in a [Ca 2+ ] i rise in NEB cells, although it did evoke bronchial smooth muscle contractions. All NEBs, however, showed a reproducible rise in Fluo‐4 fluorescence after experimental application of high extracellular K + (5s; 50mM), confirming the viability and loading of the cells. Using identical protocols, hypoxia also resulted in a clear [Ca 2+ ] i rise in the human small cell lung carcinoma cell line (H146) that was used as a positive control. If indeed hypoxia is a stimulus of NEBs, the absence of a detectable increase in [Ca 2+ ] i in NEBs at least argues for a reconsideration of the proposed straightforward hypoxic signal transduction pathway. Support: FWO grant G.0085.04 (D.A.); UA grants NOI‐BOF 2003 (D.A.) and KP‐BOF 2006 (I.B.)