Figure 4. Obp49a¹ mutant animals showed normal action potential frequencies evoked by bitter tastants.

Tip recordings were performed on the indicated S-type sensilla. The action potential frequencies were based on the number of spikes produced between 50 ms and 550 ms after initiating the stimulation. (A–G) Representative traces of nerve firings from S6 sensilla and quantification of the mean action potentials induced by the indicated concentration of bitter chemicals in S-type sensilla. (A) 1 mM papaverine. (B) 50 µM berberine. (C) 1 mM quinine. (D) 1 mM denatonium. (E) 5 mM caffeine. (F) 1 mM strychnine. (G) 25 mM L-canavanine. (H) Representative traces of nerve firings from L6 sensilla and quantification of the mean action potentials induced by 10 mM sucrose in L-type sensilla. (I) Dose response analysis of the action potential frequencies elicited by papaverine, berberine, and quinine from S6 sensilla. Data are the means ±SEM (n=5—17).