Effect of Ph on Mechanotransduction of Hair Cell -- Role of Calcium-Sensing Receptor (Casr)

Functional studies of inner ear hair cells of mammals, birds, and other vertebrates are limited by the difficulty in accessing the inner ear which is embedded in the temporal bone. Patients with chronic metabolic acidosis usually have audio-vestibular dysfunction. Zebrafish lateral line was recently reported to be a useful in vivo model for studying hair cells and ototoxicity. We have demonstrated that the scanning ion-electrode technique (SIET) to be a sensitive approach for functionally assaying mechanotransducer channel (MET channel) in zebrafish. In this project, we want to understand if extracellular pH affects functions of hair cells and MET channel. If extracellular pH alter function of Ca2+ sensing receptor (CaSR) in mechanotransduction? This proposal will be designed as a three years project: The first year: Does extracellular pH affect function of hair cells and inhibition of ototoxins to MET channel? The prupose in the first year is to examine if function of MET channel is adjusted according to different extracellular pH. If the extracellular pH changes the effects of neomycin and gentamicin on MET channel? The second year: Does pH affect function of MET channel through CaSR ? The purpose in the second year is to examine if extracellular pH affects MET channel through CaSR. Embryos with CaSR gene knockdown or knockout will used to examine if functional regulation of MET channel under different pH will altered. The third year: Does pH affect function of other CaSR agonists? The purpose in the third year is to examine if pH alters the inhibition of other CaSR agonists like La3+, Gd3+. CaSR knockdown or knockout embryo will also use to examine the role of CaSR in inhibition of La3+, Gd3+ in mechanotransduction.