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Purinoceptor‐coupled Cl − channels in mouse heart: a novel, alternative pathway for CFTR regulation
Author(s) -
Duan Dayue,
Ye Lingyu,
Britton Fiona,
Miller Lisa J.,
Yamazaki Jun,
Horowitz Burton,
Hume Joseph R.
Publication year - 1999
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.1469-7793.1999.00043.x
Subject(s) - forskolin , activator (genetics) , protein kinase c , cystic fibrosis transmembrane conductance regulator , chemistry , intracellular , adenosine , biology , microbiology and biotechnology , medicine , endocrinology , phosphorylation , biochemistry , receptor , stimulation , gene
1 P 2 ‐purinoceptors couple extracellular ATP to the activation of a Cl − current ( I Cl,ATP ) in heart. We studied the molecular mechanism and intracellular signalling pathways of I Cl,ATP activation in mouse heart. 2 Extracellular adenosine‐5′‐ O‐( 3‐thiotriphosphate) (ATPγS; 100 μM) activated I Cl,ATP in both atrial and ventricular myocytes. A specific PKC inhibitor, bisindolylmaleimide blocked the effect of ATPγS while a PKC activator, phorbol 12,13‐dibutyrate (PDBu) activated a current with identical properties to I Cl,ATP . Maximal activation of I Cl,ATP by ATPγS or PDBu occluded further modulation by the other agonist, suggesting that they may activate the same population of Cl − channels. 3 Isoprenaline increased I Cl,ATP pre‐activated by ATPγS or PDBu, while isoprenaline or forskolin alone failed to activate any Cl − current in these myocytes. Adenosine 3′,5′‐cyclic monophosphothionate, a PKA inhibitor, prevented ATPγS or PDBu activation of I Cl,ATP . Thus, I Cl,ATP is regulated by dual intracellular phosphorylation pathways involving both PKA and PKC in a synergistic manner similar to cystic fibrosis transmembrane conductance regulator (CFTR) Cl − channels. 4 Glibenclamide (50 μM) significantly blocked I Cl,ATP activated by ATPγS or by the CFTR channel activator, levamisole. 5 The slope conductance of the unitary I Cl,ATP in cell‐attached patches was 11·8 ± 0·3 pS, resembling the known properties of CFTR Cl − channels in cardiac myocytes. 6 The reverse transcription polymerase chain reaction and Northern blot analysis revealed CFTR mRNA expression in mouse heart. 7 We conclude that I Cl,ATP in mouse heart is due to activation of CFTR Cl − channels through a novel intracellular signalling pathway involving purinergic activation of PKC and PKA.