Autocrine regulation of volume-sensitive anion channels in airway epithelial cells by adenosine

Luciana Musante, Olga Zegarra-Moran, Paolo G. Montaldo, Mirco Ponzoni, Luis J V Galietta

Research output: Contribution to journalArticlepeer-review

Abstract

The activity of volume-sensitive Cl- channels was studied in human tracheal epithelial cells (9HTEo-) by taurine efflux experiments. The efflux elicited by a hypotonic shock was partially inhibited by adenosine receptor antagonists, by α,β-methyleneadenosine 5'-diphosphate (αβMeADP), an inhibitor of the 5'-ectonucleotidase, and by adenosine deaminase. On the other hand, dipyridamole, a nucleoside transporter inhibitor, increased the swelling-induced taurine efflux. Extracellular ATP and adenosine increased taurine efflux by potentiating the effect of hypotonic shock. αβMeADP strongly inhibited the effect of extracellular ATP but not that of adenosine. These results suggest that anion channel activation involves the release of intracellular ATP, which is then degraded to adenosine by specific ectoenzymes. Adenosine then binds to purinergic receptors, causing the activation of the channels. To directly demonstrate ATP efflux, cells were loaded with [3H]AMP, and the release of radiolabeled molecules was analyzed by high performance liquid chromatography. During hypotonic shock, cell supernatants showed the presence of ATP, ADP, and adenosine, αβMeADP inhibited adenosine formation and caused the appearance of AMP. Under hypotonic conditions, elevation of intracellular Ca2+ by ionomycin caused an increase of ATP and adenosine in the extracellular solution. Our results demonstrate that volume-sensitive anion channels are regulated with an autocrine mechanism involving swelling-induced ATP release and then hydrolysis to adenosine.

Original languageEnglish
Pages (from-to)11701-11707
Number of pages7
JournalJournal of Biological Chemistry
Volume274
Issue number17
DOIs
Publication statusPublished - Apr 23 1999

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Autocrine regulation of volume-sensitive anion channels in airway epithelial cells by adenosine'. Together they form a unique fingerprint.

Cite this