PT - JOURNAL ARTICLE AU - Lee, Jun Ho AU - Chiba, Toshihiko AU - Marcus, Daniel C. TI - P2X<sub>2</sub> Receptor Mediates Stimulation of Parasensory Cation Absorption by Cochlear Outer Sulcus Cells and Vestibular Transitional Cells AID - 10.1523/JNEUROSCI.21-23-09168.2001 DP - 2001 Dec 01 TA - The Journal of Neuroscience PG - 9168--9174 VI - 21 IP - 23 4099 - http://www.jneurosci.org/content/21/23/9168.short 4100 - http://www.jneurosci.org/content/21/23/9168.full SO - J. Neurosci.2001 Dec 01; 21 AB - Cochlear outer sulcus cells (OSC) and vestibular transitional cells (VTC) are part of the parasensory epithelium in the inner ear and are located in homologous positions between the sensory hair cells and the cation secretory epithelial cells in the cochlea and the vestibular labyrinth. OSC are known to sustain a reabsorptive transepithelial current and to contain an immunoreactivity for P2X2purinergic receptors. This study addresses whether OSC and VTC share functional similarities and extends this hypothesis to the question of whether both cell types contain functional P2X2 receptors. The current density (Isc) was recorded with the vibrating probe technique and was found to be similar in VTC and OSC. Both gadolinium and flufenamic acid reducedIsc in VTC, as reported previously for OSC.Isc was stimulated by extracellular ATP but not by selective agonists of P2Y receptors. Purinergic receptor agonists increased Isc with a potency order of ATP &gt; 2′- and 3′-O-(4-benzoyl-benzoyl)adenosine 5′-triphosphate ≫ α,β-methyleneadenosine 5′-triphosphate in both OSC and VTC. In the presence of suramin (100 μm) or gadolinium (100 μm), the responses of ATP were inhibited significantly in both OSC and VTC. This pharmacological profile is consistent with that of the P2X2receptor. These results demonstrate that VTC participate in vestibular parasensory cation absorption and that both OSC and VTC regulate their parasensory cation flux via P2X2 receptors, which would regulate the endolymphatic concentration of the current-carrying ion species in auditory and vestibular transduction.