Differentiation of BC3H1 cells leads to expression of a variety of proteins characteristic of smooth muscle and to changes in the behaviour of intracellular Ca2+ stores. Treatment of both differentiated and undifferentiated cells with thapsigargin (2 μM) emptied their intracellular Ca2+ stores, and in the presence of extracellular Ca2+ caused an increase in cytosolic [Ca2+] that rapidly reversed after its removal. The amplitudes of these capacitative Ca2+ entry signals were 101±8 nM (n = 42) in differentiated cells and 188±16 nM (n = 35) in undifferentiated cells. Mn2+ entry in thapsigargin-treated cells, measured by recording the quenching of cytosolic fura 2 fluorescence, was 374±26% (n = 34) and 154±7% (n = 41) of control rates in differentiated and undifferentiated cells, respectively. Empty stores caused Ba2+ entry to increase to 282±20% (n = 8) of its basal rate in differentiated cells and to 187±20% (n = 8) in undifferentiated cells. Rates of Ca2+ extrusion, measured after rapid removal of extracellular Ca2+ from cells in which capacitative Ca2+ entry had been activated, were similar in differentiated (t½ = 23±2 s, n = 7) and undifferentiated (23±1 s, n = 6) cells. The different relationships between capacitative Ca2+ and Mn2+ signals are not, therefore, a consequence of more active Ca2+ extrusion mechanisms in differentiated cells, nor are they a consequence of different fura 2 loadings in the two cell types. We conclude that during differentiation of BC3H1 cells, the cation selectivity of the capacitative pathway changes, becoming relatively more permeable to Mn2+ and Ba2+. The change may result either from expression of a different capacitative pathway or from modification of the permeation properties of a single pathway.
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Research Article|
June 15 1996
Differentiation of BC3H1 smooth muscle cells changes the bivalent cation selectivity of the capacitative Ca2+ entry pathway
Lisa M. BROAD;
Lisa M. BROAD
*Department of Pharmacology, Tennis Court Road, Cambridge CB2 1QJ, U.K.
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David A. POWIS;
David A. POWIS
†Neuroscience Group, Faculty of Medicine and Health Sciences, The University of Newcastle, Newcastle, NSW 2308, Australia
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Colin W. TAYLOR
Colin W. TAYLOR
‡
*Department of Pharmacology, Tennis Court Road, Cambridge CB2 1QJ, U.K.
‡To whom correspondence should be addressed.
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Publisher: Portland Press Ltd
Received:
November 23 1995
Revision Received:
February 06 1996
Accepted:
February 14 1996
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 316 (3): 759–764.
Article history
Received:
November 23 1995
Revision Received:
February 06 1996
Accepted:
February 14 1996
Citation
Lisa M. BROAD, David A. POWIS, Colin W. TAYLOR; Differentiation of BC3H1 smooth muscle cells changes the bivalent cation selectivity of the capacitative Ca2+ entry pathway. Biochem J 15 June 1996; 316 (3): 759–764. doi: https://doi.org/10.1042/bj3160759
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