Extracellular ATP modulates ion transport via P-2Y purinoceptors in a middle-ear epithelial cell line

Mucus and cellular debris are eliminated from the middle-ear cavity through the E-tube by the mucociliary system, Depth of the periciliary fluid layer is thought to be regulated by epithelial ion transport activity, Since impairment of the mucociliary system is a key step in the development of otitis media with effusion, we investigated the ion transport mechanisms of the middle-ear epithelium using the middle-ear MESV cell line, ATP has been shown to modulate ion transport as well as various cellular functions in several cell types via purinoceptors, In order to investigate a possible modulation of the transport activity of MESV cells, we evaluated short-circuit current (I-SC) changes in response to specific stimulation of putative purinoceptors by ATP and its various analogs, ATP dramatically increased I-SC, while adenosine had no effect, thus demonstrating the presence of P-2 receptors according to the original classification by Bunrstock. The rank order of potency of purinoceptor agonists for stimulation of I-SC on the apical side (ATP>UTP>gamma-SATP much greater than beta-SADP>2-methylthio-ATP, 2MeSATP>beta,gamma-methylene-ATP, beta,gamma-MeATP) and on the basolateral side (ATP>gamma-SATP>UTF much greater than beta-SADP>2MeSATP>beta,gamma-MeATP), along with studies using selective antagonists and intracellular calcium measurements are consistent with a P-2Y receptor subtype, The ATP-induced increase in I-SC was related to sodium transport, This modulation might be of importance in stress conditions such as inflammation.