Regulation of Intracellular Ca2+ by CFTR in Chinese Hamster Ovary Cells |
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Authors: | V. Urbach B.J. Harvey |
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Affiliation: | (1) Wellcome Trust Cellular Physiology Research Unit, Department of Physiology, University College, Cork, Ireland, IE |
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Abstract: | In cystic fibrosis, the mutation of the CFTR protein causes reduced transepithelial Cl− secretion. As recently proposed, beside its role of Cl− channel, CFTR may regulate the activity of other channels such as a Ca2+-activated Cl− channel. Using a calcium imaging system, we show, in adenovirus-CFTR infected Chinese Hamster Ovary (CHO) cell monolayers, that CFTR can act as a regulator of intracellular [Ca2+] i ([Ca2+] i ), involving purino-receptors. Apical exposure to ATP or UTP produced an increase in ([Ca2+] i in noninfected CHO cell monolayers (CHO-WT), in CHO monolayers infected with an adenovirus-CFTR (CHO-CFTR) or infected with an adenovirus-LacZ (CHO-LacZ). The transient [Ca2+] i increase produced by ATP or UTP could be mimicked by activation of CFTR with forskolin (20 μm) in CHO-CFTR confluent monolayers. However, forskolin had no significant effect on [Ca2+] i in noninfected CHO-WT or in CHO-LacZ cells. Pretreatment with purino-receptor antagonists such as suramin (100 μm) or reactive blue-2. (100 μm), and with hexokinase (0.28 U/mg) inhibited the [Ca2+] i response to forskolin in CHO-CFTR infected cells. Taken together, our experiments provide evidence for purino-receptor activation by ATP released from the cell and regulation of [Ca2+] i by CFTR in CHO epithelial cell membranes. Received: 5 April 1999/Revised: 28 June 1999 |
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Keywords: | : CFTR — Intracellular Ca2+— CHO cells — Forskolin — Purinoreceptors |
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