Figure 1. Time course of ³⁶Cl⁻ uptake (A) and release (B) in U937 cells undergoing apoptosis caused by exposure to 1μm staurosporine for 4h (STS, triangles).

A, ³⁶Cl⁻ uptake (Cells 3). B, ³⁶Cl⁻ release (Cells 1) after loading with tracer for 1.5 h in RPMI medium without (Control) or with STS given in relative units (r.u.). Filled circles show Cl⁻ release from control Cells 1 into NMDG–glutamic medium free of Na⁺ and Cl⁻. The data were approximated by equations with the parameters fitted as shown in the plots. Values are means ± SEM. of 3–4 experiments, with duplicate or triplicate determinations.