TABLE 15

Efflux transport of estradiol-17β-glucuronide from the brain across the blood-brain barrier in rats (Sugiyama et al., 2001)

	Effects of Each Inhibitor (K_i) on the uptake of [³H]E₂17βG into Gene-Transfected LLC-PK1 Cells				Maximum Inhibitory Effects of Each Inhibitor on the Efflux of [³H]E₂ 17βG from the Brain in Rats^a
	Oatp1	Oatp2	Oat1	Oat3
[³H]E₂17βG	K_m = 2.58	K_m = 17.0	Not Transported	K_m = 8.43
Probenecid	74.4	72.9	31.0^b	20.0	100%
TCA	10.8	39.4	2770^b	790	100%
PAH	>5000	>5000	K_m = 85.1^b	301	20%
Digoxin	>300	0.037	>330^b	>330	40%

↵ a Effects at the maximum inhibitor concentration on the efflux of [³H]E₂-17βG from the brain after microinjection into the rat cerebrum.
↵ b Effects on the uptake of [³H]PAH into Oat1-transfected LLC-PK1 cells.