Figure 3
Current-voltage relationship. (A) Current-voltage relationship of TbIRK expressing oocytes in sodium medium (squares), potassium medium (circles) and N-methyl-D-glucamine medium (open triangels) (mean ± S.D.; n = 31 for sodium and potassium medium and n = 23 for N-methyl-D-glucamine medium). (B) The corresponding I/V relationship of water-injected oocytes in sodium medium (squares), potassium medium (circles) and N-methyl-D-glucamine medium (open triangels) (mean ± S.D.; n = 25 for sodium and potassium medium and n = 19 for N-methyl-D-glucamine medium). (C) Comparison of the I/V relationship of TbIRK expressing oocytes in potassium medium (circles) or sodium medium (squares) in presence (open symbols) or absence (closed symbols) of 10 mM CsCl (mean ± S.D.; n = 31 and 16, respectively for TbIRK-expressing oocytes and n = 25 an 14, respectively for water-injected control oocytes). (D) Inhibition by caesium was determined by changing from sodium medium to potassium medium containing different CsCl concentrations at −80 mV. The observed currents normalized to the response elicited by potassium medium in the absence of caesium. The inhibition curve was fitted with an IC50 of 0.74 ± 0.11 mM (mean ± S.E.M.; n = 7).
