Thimerosal-induced Ca2+ Mobilization in Isolated Guinea Pig Cochlear Outer Hair Cells
| Autor: | Lei Chen, Toshio Yamashita, Narinobu Harada |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Guinea Pigs
In Vitro Techniques Pertussis toxin Calcium in biology Guinea pig chemistry.chemical_compound Cytosol Nifedipine Lanthanum Caffeine medicine Animals Cochlear Outer Hair Cells Dose-Response Relationship Drug Ryanodine Ryanodine receptor Thimerosal Biological Transport General Medicine Anatomy Molecular biology Dithiothreitol Hair Cells Auditory Outer Otorhinolaryngology chemistry Calcium sense organs medicine.drug |
| Zdroj: | Acta Oto-Laryngologica. 118:28-33 |
| ISSN: | 1651-2251 0001-6489 |
| Popis: | Intracellular calcium mobilization of isolated guinea pig cochlear outer hair cells (OHCs) was investigated using thimerosal, a -SH group oxidizing agent, and fura-2 fluorescence ratio imaging microscopy. In the presence of thimerosal, intracellular Ca2+ concentrations ([Ca2+]i) of OHCs were elevated in a dose-dependent manner. Even in Ca(2+)-free medium, Ca2+ response was still induced. The effects of thimerosal on [Ca2+]i were completely blocked and reversed by dithiothreiotol (DTT). Neither 1-100 microM ryanodine nor 5-20 mM caffeine altered the effects of thimerosal. Pretreatment with pertussis toxin (PTX) for 30 min did not affect the thimerosal-induced increase in [Ca2+]i. The increase in [Ca2+]i when Ca2+ was added during thimerosal application in Ca(2+)-free medium was almost completely blocked by 500 microM LaCl3, while nifedipine did not inhibit further increase in [Ca2+]i caused by thimerosal. Thus, oxidation of the -SH group of the OHC membrane can induce a Ca2+ release from intracellular Ca2+ stores, which are ryanodine- and caffeine-insensitive, and Ca2+ influx through non-specific Ca2+ channels, but not the nifedipine-sensitive Ca2+ channels. The possible oxidation of -SH group gated Ca2+ channels in OHCs is worthy of further study. |
| Databáze: | OpenAIRE |
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