Figure 7. Effects of purinergic receptor antagonists on the ATP-induced [Ca²⁺]_i increase.

A, representative time courses showing effects of P₂ antagonists suramin (10⁻⁴ M) and PPADS (10⁻⁴ M) on [Ca²⁺]_i increases in response to ATP (10⁻⁴ M) obtained from a single neurone. The break in the trace is approximately 5 min. B, summary data for Δ[Ca²⁺]_i in response to ATP (control, □ and ) and ATP plus the P₂ antagonist (▪). Post-controls were obtained 10-20 min after withdrawal of each antagonist. * Significantly different (P < 0.05) from the mean of the pre- and post-control values obtained with ATP alone.