Salient characteristics of TX100 and NP-40–induced MEND. In A and B, the pipette solution contained 2 mM ATP and 0.2 mM GTP. C is without nucleotides, D is with 2 mM AMP-PNP and no other nucleotides, and E is with 2 mM ATP and 0.2 mM GTP. (A) Average MEND responses of BHK cells upon the application of four different concentrations of TX100 (n = 5–7). (B) Concentration dependence of the maximal rate of change of C_m by applying TX100 in A. The response rate increases with roughly the fourth power of the concentration, given by solid line. (C) MEND in a small BHK cell at 22°C. Variance of RMS noise of C_m increases immediately upon the application of NP-40 and decreases during the decline of C_m. The inset shows the residual signal after subtracting an exponential function from the declining C_m signal. (D) MEND induced by 120 µM NP-40. Upon the application of NP-40, MEND is preceded by a rapid rise of cell C_m, and MEND stops within 2–3 s upon removing detergent. After a second MEND response, detergent causes small increases of C_m that reverse almost as quickly as solutions can be changed. (E) Rapid pipette perfusion of 150 µM NP-40 into a BHK cell by pipette perfusion. As in four additional experiments, NP-40 has no effect from the cytoplasmic side, nor does intracellular detergent have any evident influence on the MEND response to extracellular detergent.