TABLE 1.

Effect of two purinergic antagonists on the cytosolic-free-calcium peak increase (Δ[Ca²⁺]_i) induced in THP-1 cells stimulated with heat-treated filtered cell-free PBS-20 mM HEPES conditioned for 2 h by the addition of A. castellanii trophozoites (6 × 10⁶/ml) (cPBS) or PBS-20 mM HEPES containing 20 mM ADP₀^a

Sample	Mean Δ[Ca2+]i (nM) ± SE with:
	No treatment	Suramin (P2x-P2y2 antagonist) at:			PPADS (P2x-P2y1,4,6 antagonist) at:
		10 μM	15 μM	20 μM	5 μM	10 μM
cPBS	189.27 ± 14.19	48.15 ± 5.22∗	25.37 ± 3.34∗	0 ± 0∗	211.19 ± 26,56§	207.38 ± 14.96§
PBS-ADP0 (20 μm)	198.83 ± 13.82	36.89 ± 2.18∗	15.08 ± 2.02∗	0 ± 0∗	232.47 ± 35.20§	224.44 ± 46.19§

^aCell stimulation was obtained with 80 μl of the samples indicated. Values are means ± the standard error of at least six experiments. ∗, P < 0.01 versus the respective controls; §, not significant. The basal value of the [Ca²⁺]_i in THP-1 cells is 133.55 ± 3.58 nM (n = 45).