Efflux of potassium ion is an important reason of HL-60 cells apoptosis induced by tachyplesin.

To investigate the role of intercellular potassium in tachyplesin-induced HL-60 cells apoptosis. The concentration of intercellular potassium, cell volume and mitochondrial membrane potential were examined by flow cytometry. The concentration of intercellular potassium reduced in a time-dependent manner in tachyplesin-treated HL-60 cells. In addition, the loss of mitochondrial membrane potential was tightly coupled with the shrinkage of cell volume. Different caspase inhibitors protected against DNA degradation but did not prevent the loss of HL-60 cell viability induced by tachyplesin. Ba2+, which was a kind of blocker of volume-regulatory K+ channels, increased the viability of tachyplesin-treated HL-60 cells and maintained mitochondrial membrane potential and cell volume. Efflux of K+ was an important reason for apoptosis in tachyplesin-treated HL-60 cells. Efflux of K+ affected the viability of tachyplesin-treated HL-60 cells independent of the process of caspase activation.