Nitric oxide inhibits adenosine 5'-triphosphate-induced Ca2+ response in inner hair cells of the guinea pig cochlea.
To investigate the interaction between Ca(2+) and nitric oxide (NO) in inner hair cells of the guinea pig cochlea (IHCs), the extracellular adenosine 5'-triphosphate (ATP)-induced NO production and the effects of NO on ATP-induced increase of intracellular Ca(2+) concentrations ([Ca(2+)](i)) were investigated in IHCs using the NO-sensitive dye DAF-2 and the Ca(2+)-sensitive dye Fura-2. Extracellular ATP induced an increase in DAF-2 fluorescence, which thus indicates NO production in IHCs. The ATP-induced NO production was mainly due to Ca(2+) influx through the activation of P2 receptor. L-N(G)-nitroarginine methyl ester, a NO synthesis inhibitor, enhanced the ATP-induced [Ca(2+)](i) increase in IHCs while S-nitroso-N-acetylpenicillamine, a NO donor, inhibited it. We conclude that NO inhibits the ATP-induced [Ca(2+)](i) increase in IHCs by a negative-feedback mechanism.
Shen
Jing
J
Hearing Research Laboratory, Department of Otolaryngology, Kansai Medical University, Fumizonocho 10-15, Moriguchi, 570-8507, Osaka, Japan.
Harada
Narinobu
N
Yamashita
Toshio
T
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003051:Cochlea / Q000166:cytology*; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000145:classification / Q000494:pharmacology; D019793:Fluorescein / Q000032:analysis; D016257:Fura-2 / Q000032:analysis; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000494:pharmacology; D013498:Suramin / Q000494:pharmacology; D013997:Time Factors; D019323:omega-N-Methylarginine / Q000145:classification / Q000494:pharmacology
C111205:4,5-diaminofluorescein; D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D013498:Suramin; D000255:Adenosine Triphosphate; D002118:Calcium; D019793:Fluorescein; D016257:Fura-2