Figure 5

Influence of tBHP on cholinergic receptor-mediated changes in cytosolic calcium measured in the absence of extracellular calcium. Intracellular calcium levels were measured in CHO-M3 cells in the absence (Control) and presence of 1.0 – 10 mM tBHP (90 min), as indicated. Carbamylcholine (50 μM) was added at the time indicated by the first arrow. Calcium was reintroduced to the extracellular medium at the point indicated by the second arrow (final concentration = 2 mM). Results from a representative experiment involving 25 cells are shown; the experiment was performed 4 times with essentially similar results. Calcium responses (both initial peak response and plateau level response following calcium reintroduction of calcium) were significantly lower in the presence of any concentration of tBHP (1–10 mM); the corresponding responses following exposure to the different concentrations of tBHP (1 – 10 μM) were not different from each other (p > 0.05, ANOVA and Tukey’s test; N = 4).