Expression of functional purinergic receptors in pulmonary neuroepithelial bodies and their role in hypoxia chemotransmission

Adenine nucleotides act through specific cell surface receptors to invoke a variety of biological responses. Here we show that cells of neuroepithelial bodies (NEB), presumed O(2) airway sensors in neonatal hamster lung, express functional P2X receptors (P2XR). Positive immunostaining was detected in NEB cells using doublelabel immunohistochemistry with antibodies against P2X(2) and P2X(3) receptor subunits, which colocalized with serotonin (5-HT), a marker of NEB cells. For electrophysiological characterization of P2X(2)-R in NEB cells, fresh neonatal hamster lung slice preparation was used. Under wholecell patch clamp, perfusion with ATP induced a concentrationdependent, nondesensitizing inward current (EC(50)=12 muM). Perfusion with alpha,beta-methylene ATP also induced a slowdesensitizing inward current (EC(50)=8.2 muM). Suramin (IC(50) ca. 43 muM) and TNPATP (IC(50) ca. 8 muM) blocked the currents evoked by both ATP and alpha,beta-methylene ATP. Using carbon fiber amperometry we observed that hypoxia and ATP induced 5-HT release from NEB cells and that this release was blocked by suramin. These data suggest that functional P2X(2/3) heteromeric receptors are expressed in NEB cells. The possible function of these purinoreceptors in NEB cells could include modulation of hypoxia chemotransmission.