Figure 3.

High external [K⁺] reduces STS-induced cyt c release. (a) Incubation of cells with either 10 or 50 μM z-VAD-fmk, a pan-caspase inhibitor, did not block the STS-induced cyt c release (n=4). (b) HeLa cells preincubated in either culture medium (5 K) or 70 or 140 K solutions were challenged with STS for 4 h to assess cyt c release by western blot assay and using β-tubulin as loading control. Notice that the different external [K⁺] did not change the basal release of cyt c. (c) The basal level of cyt c was high because of the absence of serum for 24 h (see Supplementary Figure 1). However, the STS-induced cyt c release was significantly reduced only by 140 K (n=4). ^*P<0.05