FIGURE 4.

Class II AMP-induced apoptosis leads to dramatic increases in intracellular Ca²⁺ that are in part due to both nonspecific and voltage-gated Ca²⁺ channels. Parasites were preloaded with the calcium-dependent fluor Fura 2AM, then treated with PG-1 (C-I) and pexiganan (C-II), and analyzed for increasing fluorescence (A). Controls include cells left untreated (−) and those treated incubated in buffer containing 25 μm CaCl_2. The arrow indicates the starting baseline elevated intracellular calcium in the sample just after the addition of and mixing of AMP and placement into the detector. The effects of inhibition of nonspecific and voltage-gated calcium channels (using flufenamic acid (FFA) and verapamil (Vpl), respectively) on calcium delocalization were tested as described in A except that cells were preincubated with the designated inhibitors for 30 min prior to incubation with AMP (B). The Ca²⁺-ATPase thapsigargin (TG) was also included as a positive control for release of cytosolic calcium.