TABLE 2.

Apparent potencies (IC₅₀ values) for nerve agents to inhibit in vitro AChE activity in brain extracts, RBCs, plasma, and whole blood of male and female guinea pigs of different ages Data are presented as mean and SD of results obtained from three assays each carried out in triplicate using tissue samples from five animals per age and sex group. IC₅₀ values were derived from the fit by the Hill equation of the concentration-response relationships for each nerve agent to inhibit the AChE activity in a given tissue sample.

Nerve Agent	Tissue	IC50
		Male PND5–10	Female PND5–10	Male PND35–45	Female PND35–45
		nM
VX	Brain	1.92 ± 0.07***	2.14 ± 0.07***	2.07 ± 0.05***†	2.05 ± 0.24***
	RBC	1.20 ± 0.10	1.16 ± 0.06	1.55 ± 0.38	1.17 ± 0.03
	Plasma	1.01 ± 0.08	1.14 ± 0.02	0.88 ± 0.08	0.71 ± 0.05
	Whole blood	1.28 ± 0.06	1.35 ± 0.25	1.84 ± 0.25	1.64 ± 0.22
Soman	Brain	2.52 ± 0.20***	2.53 ± 0.13***	2.33 ± 0.23***	2.47 ± 0.08***
	RBC	0.88 ± 0.21	0.79 ± 0.21	0.79 ± 0.14	0.88 ± 0.16
	Plasma	0.84 ± 0.12	0.87 ± 0.12	0.78 ± 0.09	0.80 ± 0.13
	Whole blood	1.21 ± 0.07	1.27 ± 0.09	1.08 ± 0.04	1.12 ± 0.04
Sarin	Brain	5.65 ± 0.55***	5.66 ± 0.36***	6.15 ± 0.38***	6.03 ± 0.12***
	RBC	3.94 ± 0.42	3.73 ± 0.48	3.27 ± 0.15	3.34 ± 0.06
	Plasma	4.05 ± 0.31	4.13 ± 0.65	4.29 ± 0.55	4.11 ± 0.23
	Whole blood	3.88 ± 0.04	3.80 ± 0.12	3.66 ± 0.12	3.90 ± 0.34

^***Asterisks indicate that the IC₅₀ value for a particular nerve agent to inhibit AChE in that tissue is significantly different from the IC₅₀ value for that agent to inhibit the enzyme activity in other tissues within a group of animals (one-way ANOVA followed by Tukey's test; P < 0.001)

^†Dagger indicates that, according to one-way ANOVA followed by Tukey's test, the IC₅₀ value for VX to inhibit AChE in brain extracts differs at P < 0.01 from its IC₅₀ value to inhibit RBC and whole blood AChE. No sex or age effect was observed on the IC₅₀ values for VX, soman, and sarin to inhibit AChE in the various tissues of neonatal and prepubertal guinea pigs of both sexes