title: Hyposmotic stimulation-induced nitric oxide production in outer hair cells of the guinea pig cochlea.
abstract: Nitric oxide (NO) production during hyposmotic stimulation in outer hair cells (OHCs) of the guinea pig cochlea was investigated using the NO sensitive dye DAF-2. Simultaneous measurement of the cell length and NO production showed rapid hyposmotic-induced cell swelling to precede NO production in OHCs. Hyposmotic stimulation failed to induce NO production in the Ca2+-free solution. L-NG-nitroarginine methyl ester (L-NAME), a non-specific NO synthase inhibitor and gadolinium, a stretch-activated channel blocker inhibited the hyposmotic stimulation-induced NO production whereas suramin, a P2 receptor antagonist did not. S-nitroso-N-acetylpenicillamine (SNAP), a NO donor inhibited the hyposmotic stimulation-induced increase in the intracellular Ca2+ concentrations ([Ca2+]i) while L-NAME enhanced it. 1H-[1,2,4]oxadiazole[4,3a]quinoxalin-1-one, an inhibitor of guanylate cyclase and KT5823, an inhibitor of cGMP-dependent protein kinase (PKG) mimicked effects of L-NAME on the Ca2+ response. Transient receptor potential vanilloid 4 (TRPV4), an osmo- and mechanosensitive channel was expressed in the OHCs by means of immunohistochemistry. 4alpha-phorbol 12,13-didecanoate, a TRPV4 synthetic activator, induced NO production in OHCs. These results suggest that hyposmotic stimulation can induce NO production by the [Ca2+]i increase, which is presumably mediated by the activation of TRPV4 in OHCs. NO conversely inhibits the Ca2+ response via the NO-cGMP-PKG pathway by a feedback mechanism.
authors.affiliation: Hearing Research Laboratory, Department of Otolaryngology, Kansai Medical University, Fumizonocho 10-15, Moriguchi, Osaka 570-8507, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takeda-Nakazawa
authors.forename: Narinobu
authors.initials: N
authors.lastname: Harada
authors.forename: Jing
authors.initials: J
authors.lastname: Shen
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kubo
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Zenner
authors.forename: Toshio
authors.initials: T
authors.lastname: Yamashita
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002227:Carbazoles / Q000494:pharmacology; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005682:Gadolinium / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects / Q000378:metabolism*; D007038:Hypotonic Solutions; D007211:Indoles / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009925:Organ of Corti / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009997:Osmotic Pressure; D010703:Phorbol Esters / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D012965:Sodium Chloride / Q000378:metabolism; D013498:Suramin / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000819:agonists / Q000378:metabolism
chemical_list: D002227:Carbazoles; D004791:Enzyme Inhibitors; D007038:Hypotonic Solutions; D007211:Indoles; D020030:Nitric Oxide Donors; D010703:Phorbol Esters; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D050916:TRPV Cation Channels; C073601:KT 5823; D015124:8-Bromo Cyclic Adenosine Monophosphate; D009569:Nitric Oxide; D012965:Sodium Chloride; D013498:Suramin; D026423:S-Nitroso-N-Acetylpenicillamine; D005682:Gadolinium; D019001:Nitric Oxide Synthase; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; C038958:gadolinium chloride; D011188:Potassium; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester