TABLE 1

Bisphenol A glucuronidation by hepatic microsomes

Michaelis-Menten apparent kinetic constants (V_max and K_m) for BPA glucuronidation by hepatic microsomal fractions of early-stage (54- to 57-day-old) and near-term (120- to 135-day-old) ovine fetuses and of adult sheep and humans after incubation with BPA for 20 minutes. Hepatic glucuronidation unbound intrinsic clearance (CL_int,u) and extrapolated hepatic clearance (CL_H) (mean ± S.D.).

Subjects	V_max	K_m	CL_int,u	CL_H
	pmol/mg microsomal protein per min	µM	ml/min per g of liver	ml/kg per min
Ovine fetuses
Early stage^{^a}
Female (n = 3)^{^b}	15.3 (S.E. 2.26)	4.71 (S.E. 2.95)	0.075	NA
Male (n = 3)^{^b}	8.50 (S.E. 1.70)	3.41 (S.E. 2.93)	0.044	NA
Near-term
Female (n = 3)	519 ± 258	10.8 ± 5.94	1.53 ± 1.16	4.76 ± 3.68
Male (n = 3)	446 ± 316	8.38 ± 7.05	1.93 ± 1.21	6.40 ± 4.28
Adult
Ewes (n = 3)	6086 ± 862	82.0 ± 18.1	3.93 ± 0.85	3.14 ± 0.43
Humans (n = 3)	2770 ± 250	59.6 ± 15.6	9.00 ± 2.47	7.67 ± 1.35

NA, not applicable.
↵^a At 54–57 days of pregnancy, several concentrations of BPA-G were below the LOQ (25 nM), so the data were computed together for each sex group to estimate Michaelis-Menten parameters and the associated standard errors (S.E.).
↵^b Three pools of two fetuses.