TABLE 1

Correlation coefficients (r) between the nicotine N-demethylase activity and P450 contents or specific activities in 15 human liver microsomes

Nicotine N-Demethylase Activity (20 μM Nicotine)
Nicotine N-Demethylase Activity (100 μM Nicotine)
P450 Isoform Protein Contenta
 Specific Activityb
 Protein Contenta
 Specific Activityb
r
p
r
p
r
p
r
p
CYP1A2 -0.186 -c -0.135 - 0.187 - 0.045 -
CYP2A6 0.578 <0.05 0.802 <0.001 0.202 - 0.430 -
CYP2B6 0.366 - 0.694 <0.005 0.677 <0.05 0.740 <0.005
CYP2C9 0.245 - 0.324 - 0.259 - 0.415 -
CYP2C19 -0.164 - -0.144 - 0.245 - 0.032 -
CYP2D6 0.250 - 0.107 - 0.084 - 0.221 -
CYP2E1 0.404 - 0.097 - 0.354 - 0.032 -
CYP3A4
0.369
-
0.399
-
0.515
-
0.523
<0.05

  • ↵ a Protein contents of each P450 isoform were measured by immunoblot analyses.

  • ↵ b Phenacetin O-deethylase activity (CYP1A2), coumarin 7-hydroxylase activity (CYP2A6), S-mephenytoin N-demethylase activity (CYP2B6), diclofenac 4′-hydroxylase activity (CYP2C9), S-mephenytoin 4′-hydroxylase activity (CYP2C19), bufuralol 1′-hydroxylase activity (CYP2D6), chlorzoxazone 6-hydroxylase activity (CYP2E1), and testosterone 6β-hydroxylase activity (CYP3A4) were measured as specific activities for each P450 isoform.

  • ↵ c -, not significant.