![Figure 4. Mouse Ae4 exchanger activity is not associated with changes in the membrane potential. (A) Simultaneous current clamp whole cell recordings and [Cl−]i measurements were performed on nontransfected (green circles) and Ae4-transfected cells (black circles) using a pipette solution containing 1 mM SPQ (solution L [Table 2]). The marked reduction in the intracellular [Cl−] in response to a decrease in the external Cl− was used to confirm Ae4 expression in Ae4-transfected cells (change from solution M to N [Table 2]). (B) Summary of the Cl− exit rates in nontransfected (green bar; n = 8) and Ae4-transfected cells (black bar; n = 7) calculated from linear regression analysis on the initial response to external Na+ addition to the low Cl− solution. Data are expressed as the mean ± SEM from single cells from at least three different electroporations. For Ae4, the black bar is significantly greater, “a” compared with “b” (P < 0.01, Student’s t test). (C) Membrane potential measurements from the same cells shown in A in response to a reduction in the external Cl− in nontransfected (green trace) and Ae4-transfected cells (black trace). (D) Summary of the changes in membrane potential measurements (obtained by subtracting the membrane potential values before and after reaching steady state in response to the addition of external Na+) as shown in C. Results are presented as the mean ± SEM. (E) Simultaneous voltage clamp whole cell recordings and pHi measurements were performed on Ae4-transfected cells at −100 mV (black circles; n = 5) and 0 mV (green circles; n = 5) using a pipette solution containing 100 µM BCECF (free acid; solution L [Table 2]). The marked increase in the pHi in response to a decrease in the external Cl− was used to confirm Ae4 expression in Ae4-transfected cells (change from solution M to N [Table 2]). No increase in pHi upon external Cl− reduction was observed in nontransfected cells held at −100 mV (black line; n = 5) and 0 mV (green line; n = 5), respectively. (F) Summary of the alkalinization rates displayed by Ae4-transfected cells held at −100 and 0 mV as shown in E. Data are expressed as the mean ± SEM from single cells from at least three different electroporations.](https://cdn.rupress.org/rup/content_public/journal/jgp/147/5/10.1085_jgp.201611571/5/jgp_201611571_fig4.jpeg?Expires=1767772329&Signature=smxNODeYNDWM9eyk84GmlO8FFdAdAv80d8-PU7b9ZZt-P8wf40YKMSwpAhSOkDAxTQmaIIX38wS486ehf603~NN~WTttNjR0tPceIq1iKLD-8FKzXbJbp98A7MIL1HMPLuSAQq-qtrd77KuMO7Lrz1tTE3ngeGRdzVteKh3qdc~D~YUqU5R-KI5NZAqi06H8oSHhWmsZ7o-zwozvW328-a0H6lIE9WztPYmvNuSeLPiHwP6m1bB4vcF0aIUlTnY72xSUIpwse5hcsYKHtDg82w61VLizAAi26gcoDRXZIxt76HPh0drNvoIYPH-1hi9fTI6d7a3XwOIjjiOWt17Vyw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Mouse Ae4 exchanger activity is not associated with changes in the membrane potential. (A) Simultaneous current clamp whole cell recordings and [Cl−]i measurements were performed on nontransfected (green circles) and Ae4-transfected cells (black circles) using a pipette solution containing 1 mM SPQ (solution L [Table 2]). The marked reduction in the intracellular [Cl−] in response to a decrease in the external Cl− was used to confirm Ae4 expression in Ae4-transfected cells (change from solution M to N [Table 2]). (B) Summary of the Cl− exit rates in nontransfected (green bar; n = 8) and Ae4-transfected cells (black bar; n = 7) calculated from linear regression analysis on the initial response to external Na+ addition to the low Cl− solution. Data are expressed as the mean ± SEM from single cells from at least three different electroporations. For Ae4, the black bar is significantly greater, “a” compared with “b” (P < 0.01, Student’s t test). (C) Membrane potential measurements from the same cells shown in A in response to a reduction in the external Cl− in nontransfected (green trace) and Ae4-transfected cells (black trace). (D) Summary of the changes in membrane potential measurements (obtained by subtracting the membrane potential values before and after reaching steady state in response to the addition of external Na+) as shown in C. Results are presented as the mean ± SEM. (E) Simultaneous voltage clamp whole cell recordings and pHi measurements were performed on Ae4-transfected cells at −100 mV (black circles; n = 5) and 0 mV (green circles; n = 5) using a pipette solution containing 100 µM BCECF (free acid; solution L [Table 2]). The marked increase in the pHi in response to a decrease in the external Cl− was used to confirm Ae4 expression in Ae4-transfected cells (change from solution M to N [Table 2]). No increase in pHi upon external Cl− reduction was observed in nontransfected cells held at −100 mV (black line; n = 5) and 0 mV (green line; n = 5), respectively. (F) Summary of the alkalinization rates displayed by Ae4-transfected cells held at −100 and 0 mV as shown in E. Data are expressed as the mean ± SEM from single cells from at least three different electroporations.
