Cell type–specific effects of β-ionone on flash responses of a dark-adapted RS cone (A and D), GS rod (B and E), and BS rod (C and F). Flash strengths were 2 × 104 photons/μm2 at 625 nm, 70 photons/μm2 at 500 nm, and 122 photons/μm2 at 440 nm in (A–C), respectively. Black lines, responses in Ringer’s solution; Gray lines, responses in Ringer’s solution containing β-ionone. Stimulus–response relations in (D) (at 625 nm), (E) (at 500 nm), and (F) (at 440 nm) are for the cells in (A–C), respectively. ○, Ringer’s; △, β-ionone; ◇, washout. β-Ionone selectively reduced the circulating current and sensitivity of the BS rod (C and F).