Fig. 11.

Inhibition by H₂O₂ of [³H]phosphoinositide hydrolysis. SH-SY5Y cells were prelabeled with [³H]inositol for 48 hr, resuspended in assay buffer, incubated for 10 min with the indicated concentration of H₂O₂ followed by the addition of 1 mm carbachol (A), 20 mm NaF (plus 10 μm AlCl₃) (B), or 50 μm ionomycin (C). After an additional incubation for 30 min, [³H]inositol monophosphate was measured as described in Materials and Methods. Values with each stimulant were corrected for basal [³H]inositol monophosphate production in each experiment, which are shown withsquares. D, [³H]phosphoinositide hydrolysis was calculated as the percent of control values obtained from cells exposed to each stimulant in the absence of H₂O₂. Mean ± SEM (n = 8–9). *p < 0.05 compared with agonist stimulation in the absence of H₂O₂(ANOVA with a post hoc Bonferroni test).