FIG. 2.

Disrupting the plasma membrane sodium gradient blocks IL-7- or IL-3-induced alkalinization, but inhibition of protein or ATP synthesis does not. (A) D1 cells were incubated with or without IL-7 for 5 h and not treated (None) or treated with either 1 mM ouabain or 10 μg of cycloheximide (CHX) per ml. To inhibit de novo ATP synthesis, cells were pretreated with 1 μg of antimycin A (Anti A) for 1 h. (B) FL5.12A cells were incubated with or without IL-3 for 3 h and treated or not treated as described above for D1 cells. The intracellular pH was assayed as described in Materials and Methods.