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Adenosine receptors on human airway epithelia and their relationship to chloride secretion
Author(s) -
Lazarowski E.R.,
Mason S.J.,
Clarke L.,
Harden T.K.,
Boucher R.C.
Publication year - 1992
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1992.tb14412.x
Subject(s) - secretion , receptor , adenosine , adenosine receptor , microbiology and biotechnology , airway , biology , chemistry , endocrinology , medicine , biochemistry , anesthesia , agonist
1 We have characterized an adenosine receptor subtype present in human airway epithelial cells by measuring the changes in the intracellular levels of adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) and the rate of transepithelial Cl − secretion. 2 Primary cultures of human nasal epithelium obtained from excised surgical airway epithelial tissues and the cell lines BEAS39 and CF/T43 derived from human airway epithelium were grown on plastic dishes and labelled with [ 3 H]‐adenine for measurement of intracellular cyclic AMP accumulation. Primary cultures were loaded with the calcium indicator fura‐2 to measure [Ca 2+ ] i and studied as polarized, ion transporting epithelia on collagen matrix supports for measurement of Cl − secretion. 3 Adenosine analogues stimulated cyclic AMP accumulation with a rank order of potency characteristic of an A 2 ‐receptor: 5‐N‐ethyl‐carboxamidoadenosine (NECA) > adenosine > R‐phenylisopropyladenosine ( R ‐PIA), 6‐N‐cyclopentyladenosine (CPA)>S‐PIA. NECA increased cyclic AMP accumulation in normal and cystic fibrosis (CF) primary cells as well as in the CF/T43 and BEAS39 cell lines with K 0.5 values ranging from 0.3 to 3 μ m . Preincubation with NECA resulted in the homologous desensitization of airway epithelial cells. The effect of NECA was specifically inhibited by the adenosine receptor antagonist, aminophylline, in a competitive manner. 4 The A 1 ‐adenosine receptor agonists CPA and R ‐PIA did not inhibit isoprenaline‐stimulated cyclic AMP accumulation in CF/T43 cells, and potentiating effects of the adenosine analogues were observed on forskolin‐stimulated cyclic AMP accumulation. Adenosine analogues did not cause significant changes in intracellular Ca 2+ ([Ca 2+ ] i ) in airway epithelium. 5 Adenosine analogues, applied to either the serosal or mucosal side of the polarized amiloride pretreated primary cultures, induced changes in I sc with a rank order of potency of agonists similar to that observed for stimulation of cyclic AMP accumulation. Intracellular microelectrode studies indicated that the locus of action was the apical membrane Cl − conductance. Adenosine failed to stimulate Cl − secretion in CF airway epithelium. 6 These results provide evidence for the existence of an A 2 ‐adenosine receptor that modulates intracellular levels of cyclic AMP in human airway epithelium. Activation of this receptor might lead to stimulation of Cl − secretion in amiloride pretreated normal but not CF cells.