Species Differences in Paraoxonase Mediated Hydrolysis of Several Organophosphorus Insecticide Metabolites

Table 1

Serum paraoxonase 1 specific activities (nmoles min⁻¹ mg protein⁻¹) from several mammalian species using different organophosphates as substrates.

	Chlorpyrifos-oxon	Paraoxon	Methyl paraoxon
Rabbit	141.479 ± 17.685^A	54.424 ± 6.803^A	7.530 ± 0.423^A
Female rat	68.738 ± 5.756^B	9.944 ± 1.020^B	3.294 ± 0.317^B
Goat	68.473 ± 2.497^B	5.738 ± 0.343^C	1.623 ± 0.139^CD
Sheep	66.806 ± 0.451^B	3.843 ± 0.061^D	0.937 ± 0.080^DE
Male rat	64.955 ± 0.944^B	5.821 ± 0.202^C	2.045 ± 0.183^C
Pig	41.201 ± 2.126^C	0.182 ± 0.033	0.099 ± 0.030
Cow	30.754 ± 1.419^D	0.770 ± 0.066	0.321 ± 0.050
Horse	20.986 ± 0.299^E	0.449 ± 0.016	0.575 ± 0.146

Values presented as mean ± SEM ( = 3).
Values within each column (compound) not followed by the same capital letter are significantly different ( ≤ 0.05).
Within each row (species), values followed by an asterisk are statistically similar to one another. Absence of an asterisk indicates a significant difference ( ≤ 0.05) from all of the other values with that species.