The ability of cAMP to modulate the actions of Ca2+-mobilizing agonists was studied in single Fura-2-loaded pig articular chondrocytes in primary culture. Forskolin and 8-Br-cAMP increased both the frequency and amplitude of Ca2+ oscillations induced by ATP, and, in unstimulated cells, induced single Ca2+ transients or even Ca2+ oscillations. The cAMP-dependent protein kinase inhibitor H89 totally prevented the effect of cAMP-elevating agents on Ca2+ signalling. Forskolin and 8-Br-cAMP promptly increased the rate of Mn2+ quenching, when administered in the presence of ATP, suggesting a potentiation of receptor-mediated Ca2+ influx. In Ca2+-free medium, ATP-induced Ca2+ oscillations decreased and stopped after a few cycles: subsequent ATP additions temporarily resumed the activity, an effect that could be mimicked by forskolin. The same agent induced single Ca2+ transients in 42% of the cell population maintained in Ca2+-free medium. Thapsigargin prevented Ca2+ responses to both ATP and forskolin. The results indicate a dual mechanism for cAMP-induced potentiation of Ca2+ signalling in articular chondrocytes: an increase of receptor-mediated Ca2+ influx and a positive modulation of intracellular Ca2+ release.
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September 1996
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Research Article|
September 01 1996
Dual mechanism for cAMP-dependent modulation of Ca2+ signalling in articular chondrocytes
Paola D'ANDREA;
Paola D'ANDREA
*
1Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, via Licio Giorgieri 1, 34127 Trieste, Italy
*To whom correspondence should be addressed.
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Valentina PASCHINI;
Valentina PASCHINI
1Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, via Licio Giorgieri 1, 34127 Trieste, Italy
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Franco VITTUR
Franco VITTUR
1Dipartimento di Biochimica, Biofisica e Chimica delle Macromolecole, via Licio Giorgieri 1, 34127 Trieste, Italy
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Publisher: Portland Press Ltd
Received:
March 04 1996
Revision Received:
April 30 1996
Accepted:
May 08 1996
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 318 (2): 569–573.
Article history
Received:
March 04 1996
Revision Received:
April 30 1996
Accepted:
May 08 1996
Citation
Paola D'ANDREA, Valentina PASCHINI, Franco VITTUR; Dual mechanism for cAMP-dependent modulation of Ca2+ signalling in articular chondrocytes. Biochem J 1 September 1996; 318 (2): 569–573. doi: https://doi.org/10.1042/bj3180569
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