title: Na+ absorption by Claudius' cells is regulated by purinergic signaling in the cochlea.
abstract: CONCLUSIONS
  Claudius' cells absorb Na(+) through the amiloride-sensitive epithelial sodium channel (ENaC). Transepithelial ion transport through ENaC and possibly a Cl(-) secretory pathway is regulated by P2Y purinergic signaling.
  
  
  OBJECTIVE
  The purpose of this study was to investigate ion transport in Claudius' cells and its purinergic regulation.
  
  
  METHODS
  Young adult Sprague-Dawley rats and gerbils were studied. The Claudius' cell layer on the basilar membrane was dissected from the basal turn of the cochlea. A voltage-sensitive vibrating probe was used to measure transepithelial short circuit current (I(sc) ). The baseline I(sc) of Claudius' cells was measured in the perilymph-like control solution and the change of I(sc) after application of amiloride (10 μM) or uridine triphosphate (UTP, 100 μM).
  
  
  RESULTS
  A negative baseline I(sc) was observed in the control solution (-12.50 ± 3.95 μA/cm(2), n = 8) and the addition of amiloride resulted in a decrease of I(sc) by 75.8%. The application of UTP, an agonist for P2Y purinergic receptors, led to a partial inhibition of I(sc) (by 38.2 ± 3.2%, n = 5), and subsequent addition of amiloride abolished the remaining I(sc).
authors.affiliation: Department of Otorhinolaryngology, National Medical Center, Seoul, Korea.
authors.forename: Jae Chul
authors.initials: JC
authors.lastname: Yoo
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Kyu-Hee
authors.initials: KH
authors.lastname: Han
authors.forename: Seung Ha
authors.initials: SH
authors.lastname: Oh
authors.forename: Sun O
authors.initials: SO
authors.lastname: Chang
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Marcus
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000042:Absorption; D000818:Animals; D003051:Cochlea / Q000166:cytology / Q000378:metabolism*; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D017136:Ion Transport / Q000502:physiology; D007760:Labyrinth Supporting Cells / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D058473:Receptors, Purinergic P2Y2 / Q000378:metabolism*; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism*
chemical_list: D053503:Epithelial Sodium Channels; D058473:Receptors, Purinergic P2Y2; D012964:Sodium