ATP and A1 adenosine receptor agonists mobilize intracellular calcium and activate K+ and Cl- currents in normal and cystic fibrosis airway epithelial cells.
The effect of purinergic compounds on [Ca2+]i and membrane currents of cell lines derived from the airway epithelium of normal and cystic fibrosis individuals has been investigated. 2-Chloroadenosine (2-CADO), as well as other agonists of the A1 adenosine receptors, causes a transient elevation of cytosolic [Ca2+] that is antagonized by the A1 adenosine receptor antagonist 8-cyclopentyl-1,3 dipropylxanthine (DPCPX). ATP is also effective, but at a lower extent. The [Ca2+]i increase induced by 2-CADO and ATP is abolished by preincubation with phorbol 12-myristate 13-acetate and the Ca(2+)-ATPase inhibitor thapsigargin. This latter result suggests that purinergic agonists mobilize Ca2+ from inositol 1,4,5-trisphosphate-sensitive stores. Pertussis toxin completely inhibits the effect of 2-CADO, whereas only it partially affects that of ATP, suggesting the involvement of different types of G proteins. Perforated patch clamp experiments carried out in both current clamp and voltage clamp modes show that 2-CADO and ATP activate K(+)- and Cl(-)-selective membrane currents, with a mechanism inhibited by preincubation with DPCPX and thapsigargin. These data indicate that activation of adenosine A1 receptor, in a similar way to ATP receptor, causes [Ca2+]i increase and ion channels activation through a transduction mechanism that is not impaired in cystic fibrosis airway epithelial cells.
Rugolo
M
M
Dipartimento di Biologia, Università di Bologna, Italy.
Mastrocola
T
T
Whörle
C
C
Rasola
A
A
Gruenert
D C
DC
Romeo
G
G
Galietta
L J
LJ
D015762:2-Chloroadenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000328:Adult; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008564:Membrane Potentials; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1 / Q000187:drug effects*; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D014132:Trachea / Q000378:metabolism* / Q000502:physiology / Q000503:physiopathology; D014970:Xanthines / Q000494:pharmacology
D018118:Chloride Channels; D015221:Potassium Channels; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D013729:Terpenes; D014970:Xanthines; D015762:2-Chloroadenosine; D019284:Thapsigargin; D000255:Adenosine Triphosphate; C051360:1,3-dipropyl-8-cyclopentylxanthine; D002118:Calcium