林豊益Li-Yih Lin莊偉民Wei-Min Chuang2019-09-052018-1-212019-09-052012http://etds.lib.ntnu.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=id=%22GN0699430321%22.&%22.id.&http://rportal.lib.ntnu.edu.tw:80/handle/20.500.12235/104393毛細胞的機械性傳導通道（mechanotransducer channel, MET channel）會受到機械性刺激而開啟。陽離子經由MET通道流入造成毛細胞發生去極化，而釋放神經傳遞物質。胺基糖苷類（aminogly- cosides, AGs）抗生素在臨床上被用於治療革蘭氏陰性菌感染的疾病，但是AGs常導致許多副作用包括內耳毛細胞的損傷，甚至聽力喪失。魚類側線毛細胞為一種機械性接受器，負責感覺外在水體的流動。哺乳動物內耳與魚類側線的毛細胞，兩者不論是構造形態或功能特性都有相似之處，因此斑馬魚常被採用作為耳毒性藥物篩選的模式動物。然而對於毛細胞MET通道的特性目前仍沒有很好的驗證方式。本研究應用非侵入掃描式離子選擇電極技術(scanning ion-selective electrode technique, SIET)，針對斑馬魚胚胎的MET通道進行特性分析。毛細胞的纖毛束經微電極的機械性刺激後，可記錄到鈣離子流入，但是鉀離子與鈉離子的通透並不顯著。並且鈣離子流入會被AGs（neomycin和gentamicin）的短時間（30分鐘）處理所抑制，顯示MET通道可能被AGs所阻斷。將環境中鈣離子濃度從0.2 mM提高到2 mM，可減少neomycin和gentamicin對MET通道的阻斷；而提高水中的鎂離子濃度到5 mM，卻只能降低gentamicin對MET通道的阻斷。Amiloride過去被認為是一種MET通道的阻斷劑。本研究發現amiloride並無法阻斷側線毛細胞MET通道的鈣離子流入，但卻可降低AGs對MET通道的阻斷作用。The mechanotransducer (MET) channel on hair cells is gated by mechanical stimulation. Cation influx via MET channels causes depolarization of hair cells and eventually releasing of neurotransmitters.Aminoglycosides (AGs) antibiotics are clinically used to treat gram-negative bacterial infections, but they often cause side effects including damage of inner ear hair cells or even hearing loss. Fish lateral-line hair cells are mechanoreceptors for ambient current sensation. Since the lateral-line hair cells share structural and functional properties with mammalian inner ear hair cells, zebrafish has been used as a model animal for hair cell and ototoxicity studies. However, the property of MET channel in zebrafish hair cells has not been well examined. In this study, a non-invasive scanning ion-electrode technique (SIET) was applied to analyze the properties of MET channels in intact zebrafish embryos. Inward Ca2+ but not K+ and Na+ fluxes were recorded at the base of hair bundles as they were deflected by the microelectrode. The Ca2+ influx was suppressed by short-term treatment (30 min) of AGs (neomycin and gentamicin), suggesting that MET channels were blocked by AGs. Elevating external Ca2+ level (0.2 to 2 mM) neutralized the blockade of neomycin and gentamicin. However, elevating the Mg2+ level up to 5 mM only neutralized the blockade of gentamicin but not neomycin. Amiloride was considered as a MET channel blocker in previous studies, however, we found that amiloride cannot block Ca2+ influxes of MET channels, but it can neutralize the blockade of AGs.斑馬魚側線毛細胞機械性傳導通道胺基糖苷類抗生素Amiloridezebrafishlateral-linehair cellsmechanotransducer channelaminoglycoside antibioticsAmiloride