Receptor potential of the frog taste cell in response to bitter stimuli

Molecular mechanisms of generation of the receptor potential in the bullfrog taste cell for bitter stimuli were investigated with an intracellular recording technique. During generation of the receptor potential in response to bitter stimuli, the input resistance of the taste cell increased slightly. We could not find the reversal potential for the depolarizing receptor potential induced by quinine-HCl(Q-HCl). The Q-HCl-induced response was increased with decreasing Cl- concentration in the superficial fluid. The Q-HCl response was greatly reduced by interstitial furosemide, as a blocker of Na+/Cl- cotransport, indicating that a Na+/Cl- cotransport occurs through the basolateral membrane of Q-HCl sensitive taste cells. Therefore it is concluded that the receptor potential for Q-HCl stimulation is produced by an active secretion of intracellularly accumulated Cl- through Cl- pumps of the apical receptive membrane.