Table 2

Correlation and multiple regression analyses of APAP glucuronidation activity

Acetaminophen-UGT versus
rvalueP value
Bilirubin-UGT (UGT1A1)0.660.0016
Imipramine-UGT (UGT1A4)0.470.037
UGT1A6 protein (UGT1A6)0.300.19
Propofol-UGT (UGT1A9)0.85<0.001
Androsterone-UGT (UGT2B)−0.180.45
Phenacetin-O-deethylase (CYP1A2)0.260.27
Multiple linear regression 0.92<0.001
Constant (b 0= −1.65 ± 1.62)0.32
Bilirubin-UGT (b 1= 0.26 ± 0.12)0.045
UGT1A6 protein (b 2= 0.17 ± 0.11)0.14
Propofol-UGT (b 3 = 0.73 ± 0.12)<0.001

Activities and relative UGT1A6 protein content were determined using a subset of human liver microsomes (n = 20) and compared using correlation and multiple linear regression analyses of rank transformed data as described under Materials and Methods. Acetaminophen glucuronidation activity was measured at 0.5 mM substrate concentration. Data represent the rank order correlation coefficients (r) and P values for the indicated comparisons as well as the intercept (b0) and standardized regression coefficients (b1–3) for the multiple regression analysis.