RT Journal Article SR Electronic T1 P2X2 Receptor Mediates Stimulation of Parasensory Cation Absorption by Cochlear Outer Sulcus Cells and Vestibular Transitional Cells JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 9168 OP 9174 DO 10.1523/JNEUROSCI.21-23-09168.2001 VO 21 IS 23 A1 Lee, Jun Ho A1 Chiba, Toshihiko A1 Marcus, Daniel C. YR 2001 UL http://www.jneurosci.org/content/21/23/9168.abstract 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 > 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.