title: Nitric oxide/cyclic GMP pathway attenuates ATP-evoked intracellular calcium increase in supporting cells of the guinea pig cochlea.
abstract: We demonstrate here that nitric oxide (NO) attenuates ATP-evoked calcium transients in Deiters' and Hensen's cells, "supporting" (nonsensory) cells of the guinea pig cochlea, by means of activation of soluble guanylyl cyclase and protein kinase G. The enzymatic activities associated with the nitric oxide/cGMP/protein kinase G pathway had previously been demonstrated to be present in Deiters' and Hensen's cells. We now isolate these cells and measure changes in intracellular free calcium by using the calcium indicator fluo-3. In Deiters' cells, calcium increased rapidly in response to the application of ATP. The increase was attenuated when the pathway was stimulated by NO donors (diethylamine NONOate or sodium nitroprusside) or the cyclic GMP analog, 8-bromo-cyclic GMP. When the activation of the pathway was blocked by the additional presence of inhibitors of soluble guanylyl cyclase (LY83583) or protein kinase G (Rp-8-bromo-cyclic GMP or KT5823), the response to ATP was restored. The reactions also occurred in calcium-free media. Hensen's cells responded similarly. These results provide evidence that intracellular calcium is regulated by the NO/cGMP/protein kinase G pathway in the inner ear.
authors.affiliation: Kresge Hearing Research Institute, University of Michigan, Ann Arbor 48109-0506, USA.
authors.forename: T
authors.initials: T
authors.lastname: Matsunobu
authors.forename: J
authors.initials: J
authors.lastname: Schacht
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002227:Carbazoles; D002470:Cell Survival / Q000502:physiology; D003051:Cochlea / Q000166:cytology / Q000201:enzymology*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006168:Guinea Pigs / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology; D066298:In Vitro Techniques; D007211:Indoles; D009569:Nitric Oxide / Q000378:metabolism*; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D013873:Thionucleotides
chemical_list: D000470:Alkaloids; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D047428:Protein Kinase Inhibitors; D013873:Thionucleotides; C073601:KT 5823; C083763:8-bromoguanosino-3',5'-cyclic monophosphorothioate; D015124:8-Bromo Cyclic Adenosine Monophosphate; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D002118:Calcium