Figure 1.

High extracellular [K⁺] inhibits activation of caspases by STS in HeLa cells. Caspase-9, -3 and -8 activities were assessed as indicated in Materials and Methods section. The caspase inhibitor-corrected fluorescence signal induced by STS was taken as 100% for each caspase. STS activated caspase-9, -8 and -3 about 20-, 10- and 100-fold, respectively. This activation was significantly inhibited by preincubating cells for 30 min in 70 or 140 K solutions. n=5. ^*P<0.05