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Simultaneous measurements of changes in sarcoplasmic reticulum and cytosolic [Ca 2+ ] in rat uterine smooth muscle cells
Author(s) -
Shmigol A. V.,
Eisner D. A.,
Wray Susan
Publication year - 2001
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 - 10.1111/j.1469-7793.2001.0707h.x
Subject(s) - thapsigargin , extracellular , endoplasmic reticulum , cytosol , carbachol , calcium , chemistry , biophysics , endocrinology , medicine , fura 2 , depolarization , myometrium , agonist , uterus , receptor , biology , biochemistry , enzyme
1 The role of the sarcoplasmic reticulum (SR) was investigated in spontaneous and agonist‐induced uterine Ca 2+ transients, by combining low‐ (mag‐fluo‐4) and high‐affinity (fura‐2) indicators to measure intraluminal SR ([Ca 2+ ] L ) and cytosolic ([Ca 2+ ] i ) calcium concentration, simultaneously, in single smooth muscle cells from pregnant rat uterus. 2 Carbachol or ATP, in the absence of extracellular Ca 2+ , decreased [Ca 2+ ] L and increased [Ca 2+ ] i . Although some replenishment (around 50 %) occurred in its absence, extracellular Ca 2+ was required for full replenishment of the SR Ca 2+ . 3 In 4/15 cells, ATP evoked oscillations of [Ca 2+ ] i . These were accompanied by successive release and re‐uptake of SR Ca 2+ . Inhibition of the SR Ca 2+ ‐ATPase with thapsigargin abolished the oscillations and luminal changes. 4 Spontaneous [Ca 2+ ] i transients produced no detectable changes in [Ca 2+ ] L . The larger [Ca 2+ ] i transients evoked by high‐K + depolarisation increased [Ca 2+ ] L . Spontaneous activity was inhibited when [Ca 2+ ] L was increased. 5 These data show that it is possible to simultaneously measure SR and cytosolic [Ca 2+ ], and to investigate their response to agonist application and spontaneous activity.