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. 2011 Feb;137(2):155–172. doi: 10.1085/jgp.201010470

Figure 4.

Figure 4.

DPA and multiple ionophores show low sensitivity to TX100-promoted MEND. BHK cells with standard solutions containing 2 mM ATP and 0.2 mM GTP on the cytoplasmic side. (A) 2 µM DPA is applied twice before and twice after the induction of MEND by 200 µM TX100 at 22°C. DSF, 4.4. MEND amounts to 54% of Cm, whereas the capacitive DPA signals decrease by 28%. DPA currents are unchanged by MEND but double upon warming to 37°C. (B) 10 µM CCCP is applied and removed four times before and four times after inducing MEND with 200 µM TX100. To generate outward proton transport, the cytoplasmic solution was set to pH 6.5 and the extracellular solution was set to 7.8. A 51% MEND response results in a 13% decrease of the CCCP current. (C) Composite results for several electrogenic membrane probes. In all cases, TX100 causes an ∼50% loss of Cm. DPA-capacitive signals (n = 5) and CCCP currents (n = 6) are decreased by 25% on average. The conductance induced by 12 µM nonactin (n = 4) and 25 µM valinomycin (n = 4) is increased on average by 15 and 27%, respectively, after TX100-induced MEND. The conductance induced by the application and removal of 65 µM nystatin (n = 4) is decreased by 15% (n = 4).