Fig. 5.

PI-PLC sensitizes cultures to C′-dependent toxins. Whereas exposure of vehicle-pretreated mixed cultures (white bars) to anti-GluR3 (0.4 mg/ml) produces only modest cytotoxicity, PI-PLC-pretreated cultures (0.6 U/ml for 30 min;black bars) are destroyed by anti-GluR3 (*p < 0.05). Pretreatment with PI-PLC does not dramatically enhance the toxicity produced by the non-C′-dependent toxins KA (80 μm) or l-AA (1 mm), and PI-PLC treatment is not toxic on its own. Heat-inactivated PI-PLC has no effect on the cytotoxicity produced by any compound (data not shown). Data are presented as percent unpretreated, vehicle-challenged control and are pooled from three experiments.