Patch clamp recording of the responses to three bitter stimuli in mouse taste cells

Although several pathways of bitter taste signal transduction have been pro posed in taste cells, these mechanisms have not been elucidated in detail, To investigate the diversity of responses to bitter stimuli, we recorded th e electrophysiological responses to quinine, denatonium and naringin using whole-cell patch clamp technique in isolated taste cells of C57BL/6J mice. Ten mM quinine induced depolarizing response under the current clamp mode, and inward current response under the voltage-clamp mode (holding potential -80 mV) using both K+ (with pseudo intracellular solution) and Cs+ (K+ was substituted by Cs+ in the pseudo intracellular solution) pipettes, However , when the K+ pipette was used, the membrane conductance was suppressed and activated in succession. On the other hand, the membrane conductance was o nly activated when the Cs+ pipette was used. Half to one mM denatonium indu ced depolarizing response under the current clamp mode, and outward current response under the voltage clamp mode with both pipettes, Using these pipe ttes, the membrane conductance was activated or suppressed in the individua l case. Naringin-induced responses were not detected in these measurements. These electrophysiological recordings suggest that multiple transduction m echanisms are involved in bitter taste perception in mouse taste cells.