Nucleoside transporter expression and adenosine uptake in the rat cochlea.
Even though extracellular adenosine plays multiple roles in the cochlea, the mechanisms that control extracellular adenosine concentrations in this organ are unclear. This study investigated the expression of nucleoside transporters and adenosine uptake in the rat cochlea. Reverse transcription-polymerase chain reaction revealed the expression of mRNA transcripts for two equilibrative (ENT1 and ENT2) and two concentrative (CNT1 and CNT2) nucleoside transporters. Exogenous adenosine perfused through the cochlear perilymphatic compartment was taken up by cells lining the compartment. Adenosine uptake was sensitive to changes in extracellular Na concentrations and inhibited by nitrobenzylthioinosine (an adenosine uptake blocker). The study suggests that the bi-directional nucleoside transport supports the uptake and recycling of purines and regulates the activation of adenosine receptors by altering adenosine concentrations in cochlear fluid spaces.
Khan
Abdul F
AF
Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.
Thorne
Peter R
PR
Muñoz
David J B
DJ
Wang
Carol J H
CJ
Housley
Gary D
GD
Vlajkovic
Srdjan M
SM
D000241:Adenosine / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism*; D033721:Equilibrative Nucleoside Transporter 1; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics; D033703:Nucleoside Transport Proteins / Q000235:genetics*; D010498:Perilymph / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology
D002352:Carrier Proteins; D033721:Equilibrative Nucleoside Transporter 1; D026901:Membrane Transport Proteins; D033703:Nucleoside Transport Proteins; D012333:RNA, Messenger; C438652:Slc29a1 protein, rat; D015222:Sodium Channels; C065171:cif nucleoside transporter; D013868:Thioinosine; D012964:Sodium; C001789:4-nitrobenzylthioinosine; D000241:Adenosine