Table 4

Effect of 0.4 mM coumarin on the depentylation of 100 μM MPN by human and rat microsomes

Tissue	No. of Microsomal Samples	No. of Tests^4-a	Depentylation Rate in Controls	Percent of Mean Control Depentylation Rate (mean ± S.E.)^4-b
Tissue	No. of Microsomal Samples	No. of Tests^4-a	Depentylation Rate in Controls	Control	Treated
			pmol PENT/mg protein/min, mean ± S.E.
Human
Esophagus	6	7	1.93 ± 0.40	100 ± 4	63 ± 8^4-165
Liver	2	3	10.9 ± 3.1	100 ± 5	62 ± 6^4-160
Kidney	3	4	5.34 ± 0.89	100 ± 5	38 ± 11^4-160
Large intestine	3	4	2.08 ± 0.38	100 ± 14	45 ± 22^4-150
Rat
Esophagus^4-c	2	3	10.0 ± 1.5	100 ± 3	45 ± 5^4-160
Liver^4-c	1	2	23.0 ± 6.6	100 ± 8	103 ± 9
Lung	1	2	13.1 ± 0.4	100 ± 7	107 ± 9

Phosphate buffer, MgCl₂, semicarbazide, and water (total volume about 300 μl, see Materials and Methods), microsomes (10–20 μl), and 40 μl of 5 mM coumarin in water were mixed and incubated for 15 min at room temperature with occasional stirring. Control mixtures were incubated similarly but without addition of coumarin. [³H]MPN, unlabeled MPN, and NADPH-generating system were added to give a final volume of 500 μl and a MPN level of 100 μM. Incubation was then performed, and depentylation was assayed as described under Materials and Methods.

↵4-a In each “test”, coumarin was omitted in two “control” tubes and included in two “treated” tubes. Each microsomal sample was examined in one or two such experiments.
↵4-b The results for both the control and coumarin-treated samples were divided by the mean value for the controls in the particular test and multiplied by 100. The pvalues were obtained by comparing results for the two groups using the Wilcoxon rank order test. Significant p values were <0.05 (
↵4-150 ), <0.01 (
↵4-160 ), and <0.001 (
↵4-165 ).
↵4-c These results are taken from Chen et al. (1999).