Hyposmotic stimulation-induced nitric oxide production in outer hair cells of the guinea pig cochlea.
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.
Takeda-Nakazawa
Hiroko
H
Hearing Research Laboratory, Department of Otolaryngology, Kansai Medical University, Fumizonocho 10-15, Moriguchi, Osaka 570-8507, Japan.
Harada
Narinobu
N
Shen
Jing
J
Kubo
Nobuo
N
Zenner
Hans-Peter
HP
Yamashita
Toshio
T
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
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