Fig. 2.

NH₃/NH₄⁺- and MA/MA⁺-induced currents in H₂O-injected and Rhcg-expressing oocytes. In oocytes expressing Rhcg (red tracing) or injected with H₂O (blue tracing), an inward current was observed upon switching solution from standard HEPES to NH₃/NH₄⁺ (segment ab). Inward current recovered upon return to standard HEPES solution (segment bc). Exposure to MA/MA⁺ did not cause a significant change in current (segment cd). Tracings are representative of results from 23 Rhcg-expressing and 22 H₂O-injected oocytes.