Changes in P2Y4 receptor expression in rat cochlear outer sulcus cells during development.
Extracellular adenosine triphosphate (ATP) released from cellular sources plays an important role in variety of the cochlear physiologic processes. The primary purinergic receptor subtype in the cochlea is the P2X2 receptor, which is a subtype of P2X receptor. This receptor appears to mediate a protective decrease in the electrical driving force in response to acoustic overstimulation. Outer sulcus cells (OSCs) in the cochlear lateral wall appear to maintain an adequate K+ concentration in the cochlear endolymph in response to varying intensities of auditory stimulation. However, little is known about developing OSCs. The purpose of this study was to investigate subtypes of purinergic receptors in developing rat OSCs using a voltage-sensitive vibrating probe. Results showed that only two P2 receptors (P2Y4 and P2X2) contributed to the regulation of short circuit currents in neonatal OSCs. ATP increased cation absorption via apical nonselective cation channels after activating P2Y4 receptors in early neonatal OSCs. P2Y4 expression rapidly declined postnatally and reached near adult levels on postnatal day 14. P2X2 was co-expressed with P2Y4 in early neonatal OSCs. Temporal changes in P2Y4 during OSC development might be involved in the establishment of the endolymphatic ion composition needed for normal auditory transduction and/or specific cellular differentiation.
Lee
Jun Ho
JH
Department of Otolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul National University Hospital, 28 Yeongon-dong, Chongro-gu, Seoul 110-744, Republic of Korea. junlee@snu.ac.kr
Heo
Jeong-Hwa
JH
Kim
Chang-Hee
CH
Chang
Sun O
SO
Kim
Chong-Sun
CS
Oh
Seung-Ha
SH
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D000375:Aging / Q000502:physiology*; D000818:Animals; D002412:Cations / Q000378:metabolism; D002478:Cells, Cultured; D003051:Cochlea / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D004710:Endolymph / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000187:drug effects; D008564:Membrane Potentials; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000378:metabolism*; D058476:Receptors, Purinergic P2X2; D014544:Uridine Triphosphate / Q000378:metabolism / Q000494:pharmacology
D002412:Cations; C546403:P2rx2 protein, rat; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; C104749:purinoceptor P2Y4; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D014544:Uridine Triphosphate