Ionic currents expressed in a cell line derived from the organ of Corti of the Immortomouse.
We have investigated the maturation of adult hair cell electrophysiology in a population of precursor cells in a conditionally immortal cell line. The cell line, UB/OC-2, from the embryonic organ of Corti of the H-2Kb-tsA58 transgenic mouse, permits cells to grow proliferatively at 33 degrees C and to differentiate at 39 degrees C. Whole-cell patch-clamp recordings showed that proliferating cells had a different electrophysiology to differentiating cells. Differentiating cells had a conditionally expressed slowly activating inward current activated by hyperpolarization. The current was not blocked by extracellular application of 0.5 mM Ba2+, but was blocked reversibly by 2 mM Cs+. The current was found to be carried by both K+ and Na+ ions (PK/PNa=2.2) and activated by 10 microM forskolin. These properties identify the slowly activating current as Ih. A proportion of proliferating and differentiating cells exhibited a voltage-gated Na+ current, INa. INa was abolished in Na-free external medium and was inhibited reversibly by tetrodotoxin (TTX) with Ki=64 nM. Together these results suggest that proliferating and differentiating hair cell precursors in the immortal cochlear cell line UB/OC-2 express currents which are also found in developing hair cells.
Jagger
D J
DJ
Department of Physiology, University College London, Gower Street, London, WC1E 6BT, UK.
Holley
M C
MC
Ashmore
J F
JF
D000818:Animals; D002460:Cell Line; D003051:Cochlea / Q000378:metabolism; D006198:Hair Cells, Auditory / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008822:Mice, Transgenic; D009925:Organ of Corti / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism; D015222:Sodium Channels / Q000378:metabolism; D013696:Temperature
D007473:Ion Channels; D015221:Potassium Channels; D015222:Sodium Channels