Table 4

Effects of testosterone on several P-450-mediated enzyme activities in bacterial membranes containing recombinant human P-450s or in human liver microsomes

Assay	Protein Preparation	Activities		Activity^4-a
Assay	Protein Preparation	+0 μM testosterone	+100 μM testosterone	Activity^4-a
		pmol product formed/min/pmol P-450		%
Bufuralol 1′-hydroxylase	CYP2D6	8.38 ± 0.21	7.69 ± 0.26	92
	Human liver microsomes	0.13 ± 0.01	0.08 ± 0.01^4-b	62
Coumarin 7-hydroxylase	CYP2A6	2.26 ± 0.11	2.26 ± 0.09	100
	Human liver microsomes	0.41 ± 0.09	0.33 ± 0.03^4-b	80
EROD	CYP1A2	5.86 ± 0.79	5.87 ± 0.63	100
	Human liver microsomes	0.23 ± 0.06	0.16 ± 0.04^4-b	70

Assays were performed as described in Experimental Procedures with bacterial membranes containing 10 pmol of recombinant P-450 isozymes with CPR or with human liver microsomes corresponding to 200 pmol P-450.

↵4-a Enzyme activities in absence of testosterone are taken as 100%.
↵4-b Significantly different from control p ≤ .01; data for bufuralol 1′-hydroxylase assay represent a single experiment done in quadruplicate. Data for other assays come from six independent experiments each done in triplicate.