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Role of [Ca2+]i in "Ca2+ stores depletion‐Ca2+ entry coupling’ in fibroblasts expressing the rat neurotensin receptor.
Author(s) -
Gailly P,
Hermans E,
Gillis J M
Publication year - 1996
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1996.sp021245
Subject(s) - thapsigargin , biophysics , neurotensin , calmodulin , chemistry , calcium , coupling (piping) , endocrinology , receptor , chinese hamster ovary cell , medicine , biology , endoplasmic reticulum , biochemistry , neuropeptide , materials science , organic chemistry , metallurgy
1. Transfected Chinese hamster ovary fibroblasts expressing the rat neurotensin receptor were used to study the ‘Ca2+ stores depletion‐Ca2+ entry coupling’ which follows stimulation with neurotensin and liberation of InsP3. 2. This coupling could be dissociated in time. Firstly, stores depletion was produced by neurotensin or thapsigargin which caused a first [Ca2+]i transient in a Ca(2+)‐free external medium. Secondly, readmission of external Ca2+ produced an influx of Ca2+ and a second [Ca2+]i transient. 3. Various concentrations of thapsigargin (20 nM to 1 microM) were used to produce complete stores depletion with small or large first peaks of [Ca2+]i. Upon return to external Ca2+, small or large second [Ca2+]i peaks were observed. The amplitudes of both peaks were positively correlated. 4. The Ca2+ entry which followed stores depletion could occur at very low basal values of [Ca2+]i, was accelerated by okadaic acid and inhibited by staurosporine and the calmodulin antagonist W‐7. 5. It is concluded that the rise in [Ca2+]i during Ca2+ stores depletion is an essential parameter which determines the size of the subsequent Ca2+ entry.