TABLE 4

Potencies of MPA, LNG, and ALDO to inhibit calcium influx produced by PROG, PGE1, l-sirenin, and high K⁺/high pH in human sperm

Opener	Antagonist	pIC₅₀	n
PROG	MPA	5.18 ± 0.39	12
	LNG	4.49 ± 0.23	9
	ALDO	4.48 ± 0.16	10
PGE₁	MPA	5.01 ± 0.26	11
	LNG	4.52 ± 0.11	6
	ALDO	4.24 ± 0.20	10
l-Sirenin	MPA	5.21 ± 0.33	7
	LNG	4.09 ± 0.05	5
	ALDO	4.21 ± 0.16	9
high K⁺/high pH	MPA	<5	4
	LNG	<5	4
	ALDO	<5	4

Inhibitors were evaluated in the presence of an EC₈₀ concentration of each activator (30 nM PROG, 10 nM PGE₁, 3 µM l-sirenin). Buffer containing 140 mM K⁺, pH 8.2 was added to elicit alkalinization/depolarization calcium influx. IC₅₀ values are expressed as the mean ±SD with the number of independent experiments indicated by n.