Membrane potential measurements of transitional cells from the crista ampullaris of the Gerbil |
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Authors: | Philine Wangemann Daniel C Marcus |
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Institution: | (1) Boys Town National Institute, 555 No. 30th St., 68131 Omaha, NE, USA |
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Abstract: | Transitional cells of the crista ampullaris were impaled with microelectrodes in order to record the membrane potential (PD) and to investigate membrane properties. In control solution the PD was –87±1 mV (n=103). This value is not significantly different from –83±2 mV (n=24) measured in Cl– free solution. Cl–] steps from 150 to 15 mmol/l (n=24) depolarized the membrane by about 2 mV, indicating a minor Cl– conductance. The transference number for K+ was 0.75±0.01 (n=79) obtained from the PD responses to K+ steps from 3.6 to 25 mmol/l. The cell membrane depolarized and the amplitude of PD responses to K+] steps was reduced by Ba2+ (2·10–6 to 10–3 mol/l), quinidine (10–3 mol/l), quinine (10–3 mol/l), Rb+ (20 mmol/l), Cs+ (20 mmol/l), NH4
+ (20 mmol/l) and Tl+ (0.5 mmol/l), whereas tetraethylammonium (TEA, 20 mmol/l) had no effect. The dose-response curve for Ba2+ in the presence of 3.6 mmol/l K+ was shifted to the right by approximately three decades in the presence of 25 mmol/l K+ and by a factor of about 4 in the presence of 135 mmol/l gluconate as a substitute for Cl–. Transitional cells were depolarized by ouabain, suggesting the presence of (Na++K+-ATPase.This work was supported by grants from the Deafness Research Foundation to PhW and the National Institute of Health (NS 19490) to DCM |
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Keywords: | Inner ear K+ conductance Cl– conductance Monovalent cations (Na++K+)-ATPase |
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