Table 1.

Sensitivity of U50,488 analgesia in D2, B6, and e/e mice of both sexes to blockade by MK-801

Genotype	Sex	Treatment	AD50,* mg/kg	Potency ratio,† sex	MK-801 block?
D2	Male	Saline	20.8 (15.3–28.4)	1.7 (1.1–2.6)‡	Yes
		MK-801	n.c.
	Female	Saline	35.7 (28.6–44.6)§		No
		MK-801	46.8 (37.2–58.7)
B6	Male	Saline	39.0 (27.3–55.6)	1.7 (1.1–2.5)‡	Yes
		MK-801	n.c.
	Female	Saline	65.2 (53.5–79.6)		No
		MK-801	82.4 (65.7–103.3)
e/e	Male	Saline	34.6 (26.4–45.5)	1.6 (1.1–2.3)‡	Yes
		MK-801	n.c.
	Female	Saline	54.7 (43.4–69.0)		Yes
		MK-801	n.c.

n.c., Not calculable; half-maximal analgesia was not obtained at any dose (see Fig. 2). 

^*Half-maximal analgesic dose (AD₅₀), calculated by the method of Tallarida and Murray (14). Confidence intervals of 95% are in parentheses. 

^† Calculated as female AD₅₀/male AD₅₀ (saline groups only). Confidence intervals of 95% are in parentheses. 

^‡ Males significantly more sensitive than corresponding female saline group, P < 0.05, based on potency ratio comparison with 1.0. 

^§ Significantly more sensitive than corresponding saline group in other genotypes, P < 0.05.