Fig. 1.

NH4+ and methyl ammonium (MA⁺) current (I) in Rhbg-expressing and H₂O-injected oocytes. A: in oocytes expressing Rhbg (clamped at −60 mV), exposure to NH₃/NH4+ (5 mM) induced an inward current (segment ab) of −83 ± 9.6 nA (n = 8). Exposure to methyl amine/methyl ammonium (MA/MA⁺; 5 mM) also caused an inward current (cd) of −63 ± 7.6 nA (n = 8) that was significantly smaller than the NH₃/NH4+-induced current (P < 0.001). STD, standard. B: in H₂O-injected (control) oocytes, exposure to NH₃/NH4+ (5 mM) caused an inward current (segment ab) that averaged −52 ± 7.6 nA. Exposure to MA/MA⁺ (5 mM) did not cause any significant current (cd).