Amphipath-induced MEND is facilitated by Ca transients associated with exocytosis. Cytoplasmic solutions are ATP and GTP free. (A) As with many other amphipaths that induce MEND, the threshold concentrations needed to induce MEND by TX100 are reduced by a Ca transient associated with exocytosis. In this example, 80 µM TX100 was applied twice before the activation of Ca influx, and it was without effect. After Ca influx and exocytosis, the same TX100 concentration causes a rapid 50% MEND response. (B) Similar to TX100, a low concentration of edelfosine (30 µM) is without effect before the activation of Ca influx. After a Ca influx episode, the same edelfosine concentration causes a 65% MEND response. (C) DTDP-saturated extracellular solution (5 µM; sonicated for 5 min) is without effect when applied for 5 min before the activation of reverse Na/Ca exchange. Subsequent activation of Ca influx by NCX1 causes a rapid 60% MEND response.