TABLE 5

T-type CCBs mibefradil and ML218 reduce the maximal response, whereas MPA, LNG, and ALDO reduce the potency of PROG-, PGE₁-, and l-sirenin-induced calcium influx in human sperm

Inhibitor		Progesterone			PGE₁			l-Sirenin
	Conc., µM	pEC₅₀	E_max, %	n	pEC₅₀	E_max, %	n	pEC₅₀	E_max, %	n
MBF	1	8.71 ± 0.29	90	3	8.16 ± 0.08	87	3	5.71 ± 0.01	87	2
	10	8.14 ± 0.20	69	4	8.53 ± 0.37	53	4	5.57 ± 0.41	58	4
	30	8.31 ± 0.42	23	4	8.23 ± 0.51	41	3	5.37 ± 0.51	20	4
	100	8.26 ± 0.24	16	3	—	<10	5	—	<10	3
ML218	1	8.12 ± 0.13	83	3	8.20 ± 0.10	73	3	ND
	10	7.77 ± 0.35	42	3	8.01 ± 0.05	64	3	5.61 ± 0.45	38	2
	30	—	<10	3	7.86 ± 0.04	15	3	—	4	2
	100	—	<10	3	—	<10	2	—	2	2
MPA	10	7.69 ± 0.40	106	3	7.83 ± 0.43	111	3	5.56 ± 0.15	108	3
	30	7.51 ± 0.38	99	3	7.34 ± 0.15	105	3	5.24 ± 0.58	100^a	3
	100	6.64 ± 0.07	100^a	3	6.96 ± 0.03	100^a	3	4.71 ± 0.21	100^a	3
LNG	10	7.58 ± 0.16	110	8	7.78 ± 0.30	96	4	5.16 ± 0.08	95	4
	30	7.06 ± 0.26	100^a	4	7.48 ± 0.18	106	4	4.83 ± 0.16	102	4
	100	6.64 ± 0.06	100^a	4	7.29 ± 0.22	117	4	4.52 ± 0.03	100^a	3
ALDO	10	7.44 ± 0.14	114	4	7.88 ± 0.22	107	4	5.28 ± 0.28	104	4
	30	7.09 ± 0.36	106	4	7.82 ± 0.31	99	4	5.10 ± 0.24	109	4
	100	6.59 ± 0.16	100^a	4	7.44 ± 0.31	100^a	4	4.51 ± 0.21	100^a	4

EC₅₀ values are expressed as the mean ±SD, and E_max values are the percent of a saturating concentration of PROG (3 µM). The number of independent experiments is indicated by n. EC₅₀, E_max, and n values for PROG, PGE₁, and l-sirenin in the absence of inhibitor are in Table 2. Fitted parameters were not calculated for conditions producing E_max < 10.
↵a Constrained value due to rightward shift of dose response.