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A liver arylamidase extremely sensitive to organophosphorus compounds
Life Sciences Vola 13, pp .1181-1188, 1973 . Printed in Great Britain
Perga.mon Press
A L`Vf? A?YLAMIDASP; EXmäEb1F.L Y S:'sNSI'f~IVE ^C O~GANOPHOSPH04U~ COMP(IUNUS * TetsUO SStoh Toxicity Laboratory, DepaL~tment of Pharmacology, University of Chicago, Chicago, Illinois 6063
(Received 14 June 1973 ; in final form 24 September 1973) Summary
Inhibitory effect of 7 organophosphorus compounds on the liver isocarboxazid amidase was studied in rats . This enzyme is more sensitive to the relatively leas toxic compounds, i .e ., Sumithio , mala .thion and TOTP than to the more toxic ones such as pai"athicn, paraoxon and EPN . As little as 0.5 mg/kg of Sumithian inhibited this arylamidase activity by approx . 28gß in male and 37 ;~ in female rata . TOTP completely inhibited the arylamidase in e dose of 20 mg/kg, moreover, a significant sex difference in the TOTP-induced inhibition of the enzyme was observed . Organophosphorus insecticides are known to inhibit the activity of a number of esterases (1-~) besides cholinesterase . In a previous paper" (6) the present author showed that a liver arylamidase which is referred to as isocarboxazid (ISOC) amidase, was more susceptible to EPN than cholinesterase . IS OC is a monoamine oxidase inhiEit.or and is hydrolyzed by this arylamidase to produce benzylhydrazine . This amidase is responsible for the hydrolysis of several compounds possessing amido bonding and its molecular weight was estimated to be about 220,000 (~) The purpose of the present study was to examine the effects of 7 organophosphorus compounds on ISOC amidase in vivo .
* Present addressi Department of Pharmacology and Toxicology, Institute of Food Microbiology, Chiba University, Naraehino, Chiba, Japan.
1]82
]nsecticides and Liver Arylamidase
Vol. 13, No. 9
b~aterials and Methods Adult male and female Holtzman rats were used . They were fed Rockland rat diet ad libitum and maintained in an air-conditioned room at 68 ° -75 ° F . Compounds used here were obtained from the following sources
parathion and malathion (95°~) from American
Cyanamid Co ., Princeton, N .J .~ paraoxon from Dionsanto Chemical Co ., St Louis, Mi .t EPN (recrystallized "pure") from E . I . du Pont de Nemours & Co ., iNilmington, Del i sumithion from Chemargo Co^p . . Kansas City, Mo .~ Fole~Y'from Virginia-Carolina Chemical Corp .+ TOTP from Eastman Chemical Co ., Rochester, N . Y . Chemical structures of these compounds an3 their LD50 values are shown in Table 1 . Animals were sacrificed by decapitation and enzyme activity after incubation under the conditions described in the legend of Table 2 was stopped by adding 2 ml of 1$9~ metaphosphoric acid . After standing 10 min, the mixtures were centrifuged and an aliquot of the supernatant solution was removed to another test tube containing 0 .5 ml of redistilled water . Colorimetric assay of benzylhydrazine formed from ISOC waa carried out at 490 nm by adding 1 .5 ml of p-dimethylaminobenzaldehyde (PDAB) solution freshly prepared by dissolving 1 g of PDAB in 30 ml of ethanol and 15 ml of glacial acetic acid . This is a alight modification of the procedure used in preceding studies (12-14) . Results and Discussion Animals were administered single i .p . injection of sublethal doses of organophosphorus compounds . In no case were visible signs of poisoning observed . Table 2 shows the results of these experiments . Enzyme activities of 80 male and 92 female control rats were 0 .60 .024 and 0 .4610 .038
mole benzylhydrazine/50 mg
Vol . 13, No. 9
Jnsecticides and Liver Arylamidase
1183
0 w Cu
X
C]
v2 ô v
.~L.' a
â
Insecticides and Liver Arylamidase
1 ~ 84
Vol. 13, No . 9
liver wet wt ./30 min, respectively . The differences between the activities of the two sexes were significant (P<0 .01) as indicated by Student's t test . It is clearly recognized that this enzyme is more sensitive to the relatively less toxic compounds,
i .e ., sumithion,
malathion, TOTP than to the more toxic ones such as parathion, paraoxon and
PN . As little as 0 .5 mg/kg of sumithion which is
approximately 1 .3 x 10 -3 x LD50 (see 'fable 1), inhibited the liver arylamidase activity by approximately 28 ;b in male and 37îô in female rats . In addition, the existence of a sex difference in the cases of parathion, paraoxon and EPN can be explained by the correlation with the drug metabolizing enzyme activity associated with detoxification of these insecticides . The most interesting inhibitor in this study is TO'^P . This compound has been widely used as plasticizes and it completely inhibited ISOC amidase in a dose of 20 mg/kg which corresponds to approximately 1/125 of the LD50 . moreover, a significant sex difference in the TOTP-induced inhibition of the arylamidase was observed . Casida et al . (15) and Sharma and Watanabe (16) reported that the metabolism of TOCP(TOTP) involved hydroxylation followed by cyclization and elimination of one cresyl group. Since the first reaction depends on the liver microsomal drug metabolizing enzymes, the sex difference in the inhibitory effect of TOTP on the arylamidase can be explained by the known sex difference in the activity of the drug metabolizing enzymes . From these results the cyclized compound, not TOTP itself, is expected to be the actual inhibitor . In contrast, Murphy et al .(11) ^sported that no tissue cholinesterases wei~e inhibited even at larger doses of TaTP (110 mg/kP) or malathion (150 mg/k,.r) than +,hose used here .
Vol . 13, No . 9
1185
Insecticides and Liver Arylamidase TABLE 2 Inhibition of Liver Arylamidase in vivo by Organophosphorus compounds
Compound s
Dose (mg/k~; i . p . )
Amidase activityb Male
Fema e
M/F ratio
Per cent of Control s Parathion
Paraoxon
0 .05
90 .8±7 " 58 (6)
77 .4±1 .69 (7)
1,18
0,2
81 .0±6,57 (_5)
66 .917 .42 (7)
1 .21
0 .4
35 .1±4 .40 (5)
18 . ~ 2 .01 (5)
1 .90
0 .8
2 .1'0 .87 (5)
1 .110 .52 (6)
2 .08
106 .019,81 (5)
60 .717 .05 (5)
1 .75
0 .2
73 .5 8 .51 (5)
32 .2=3 .78 (5)
2 .28
0 .4
32 .314 .07 (5)
14 .0l1 .90 (5)
2 .30
3 .010 .69 (5)
1 .2-0 .48 (5)
2 .50
0 .4
79 .712 .27 (5)
77 .516 .70 (6)
1 .03
1 .0
46 .8±2 .77 (6)
42 .715 .95 (5)
1 .10
4,0
4 .111 .12 (_5)
1 .910 .32 (5)
2 .16
0,05
o .s FP^;
a All animals were sacrificed at 3 hr after injection, b FiFUres in paranthese indicate number of animals used . c Data expressed as MeanlS .i . Compounds were dissolved in 20°~ e+hanol and 80°ô propylene glycol and administered i .p . The concentrations of the solutions of the compounds were adjusted so that the volume of injections was 1 ml/kg of body weight . Control animals were liven an equivalent volume of the vehicle, Incubation mixtures consisted of 0 .5 ml of 10;" liver homogenate, 0 .5 ml of redistilled water and 0 .5 ml of the substrate solution which was prepared by dissolving 3 .0 ~Zmoles isocarbexazid in 0,1 M phosphate buffer (pH 7 .4), Incubation time was 30 min at 37 oC and the enzyme activity was assayed as described in the ±ext,
Insecticides and Liver Arylamidase
1188
Vol. 13, No . 9
TABLE 2 (Continued) Fole~
Sumithior~
Malathion
TOTP
1
58 . 2t 7 . 61 (5)
49 . ~ 3 . 82 (5)
1 .17
5
16 .7t1 .o4 (6)
11 .4~ 0,96 (6)
1 .46
l0
4 .oto .89 (5)
4,oto,45 (5)
1 .00
20
1 .5±0 .22 (5)
1 .8to,5o (5)
0,83
0 .5
72 .0±0,78 (5)
63,2~3,55 (5)
1 .14
2
57 .2±2 .98 (5)
49 .4±5 .95 (5)
1 .16
l0
4o .5t5 .17 (5)
34 .0±2 .75 (6)
i .ly
50
38 .3±1 .59 (6)
31 .2±2 .62 (6)
1 .23
100
32 " 311 .26 (5)
18,611 .7` (5)
1 .74
2
77 .6±2 .71 (8)
100,bt 7 .72 (6)
0 .77
l0
49 .9±4 .35 (7)
50 .6±5 .65 (6)
0 .98
.50
29 .8±1 .71 (5)
26 .4±7 .44 (5)
1 .12
l00
15 .6±1 .78 (6)
15 .~+1 .29 (5)
0 .99
1
63 .2t5 .09 (9)
69 .01 2 .20 (7)
0 .92
5
16 .514,18 (8)
42 .x+1 .90 (9)
0 .39
10 20
1,7±0 .39 (5) 0.0±0 .00 (5)
22 .E 1 .42 (5) 2 .010 .43 (5)
0 .07 0 .00
On the other hand, it is known that all organophosphorus insecticides can be dealkylated to some extent by liver microsomal mixed function oxidase (17) . This reaction seems to be closely correlated with the inhibition of the liver arylamidase in this study, because p-nitrophenyl phosphoric acid :showed no inhibition even at 10~ Ivi in an experiment in vitro (not presented here) . The data shown in Table 2 demonstrate that the antiamidase activity is associated with the alkyl substitutions (?1 and R 2 in Table 1) .
Toxicities for insects as well as for mammals which have
Vol. 13, No . 9
Insecticides and Liver Arylamidase
1187
been reported closely parallel the inhibitory effects of oreanophosphorus compounds on ISOC amidase . Recently, I+lurphy and co-workers (18,19) proposed that inhibition of carboxylesterase by malathion is due to an irreversible binding to the enzyme . Moreover, detoxification of or~anophosphorus insecticides may be attributed to the bindinP of these compounds to a protein molecule other than cholinesterase . 'T'his mechanism is exactly applicable to the present study, because it is known ±hat the esterification of p-nitrophenyl phospho!°ic acid to parathion, paraoxon or ~P^I produces a marked change in the electronic nature of the phosphorus (20) and consequently, this reaction greatly increases both the anticholinesterase activi+,y an3 toxicity of~the compound . `!'his fact su~eests ±hat `he affinity of ~.he or~anophosphorus compounds for the protein molecule is dependent. upon the alkyl stoups of the compounds . Further studies on the mechanism of the effects described here a^e now in pro?ress . Acknow,led~-ment-?'he author dedicates this paper to the memory of Professor 'r,_enneth P . UuDois .
Isocarboxazid was kindly donated
by fof.fTann-La ',oghe Inc ., futley, ^'ew Jersey . Rsferences 1.
'r; . P . UuH07S, F . I: . ICIROSHI~nA and J . P . F?A'NI rY, Toxicol . Appl . Pharmac ol . 12, 273-284 (1968) .
2.
C . :-! . ~NILIiI:i'~:S and K . H . JACCBSO":, Toxicol . Appl . Pharmacol . , 40~-500 (1966) .
3.
J .~ . CASIUA, Biochem . Pharmac . ~, 332-342 (1951) .
4.
I . ". . FLUCt.HA~'_" and J . E . CASIDA, Biochem . Pharmac . 21, a_5y1-26o3 (1972) .
5.
F . iN . SFUMF and '. . D . U'B?I~:N, A~r . Food Chem . 8, 36-41(1960) .
Insecticides and Liver Arylamidase
]188
Vol . 13, No . 9
6.
T . SATOH and K . MO?OI, Toxicol . Appl . Pharmacol . in press .
7.
T . SATOH and K . MOEOI, Biochem . Pharmac . 21, 3111-3120 (1972) .
8.
Y . PdISI?IZAiNA, K . FUJII, T . u.ADOmA, J . :~îIYAY0T0 and H . SAI~~Abî0T0, A~r . Biol . Chem . (Tokyo) ~, 605-610 (1961) .
9. 10 .
Y. . P . DuBOIS, Bull . Wld . Hlth . OrP, 44, 233-240 (1971) . -. . H . D~fISHAC~i, Handbook of Poisonin~~ :~ia~nosis and Treatment, p104, Lan#e Med . Publ ., Los Altos, Calif ., 1971 . S.
T~ .
hiU~fPl?Y, ~ . L . ANO .°.50~' and _ . P . DuBGIä, Proc~3oc .
Exp . Biol . N~ed . 100, 483-487 (1y59) . 12 .
T . âATCH and K . MOROI, Anal . Chim . Acta 51, 449-454 (1970) .
13 .
T . SATOH and K . MUrOI, Biochem. Pharmac . 20, 504-507 (1971) .
14 .
T . SATOH and K . iv10?OI, Life Sci . 12, 169-175 (1973) .
15 .
J . E . CASIDA, M (1961) .
16 .
? . P . SHA3h~A and P . G . WATANABE, in Abstrac's of papers, T~ti~elfth Annual fdeetin; of Society of Toxicolo^y . p89 (Academic P_,ess, New Yo .-^k and London, 1973) .
17 .
C . DIN~dINs=,~, D . ?i . HU':SON and B . A . PICK°.°.I~+s, Bi :~chem, .7 . 126, 701-707 (1972) .
1.3 .
S . D . f.;U?PHY and Y, . L . C~EE'J'L'", Arch . Environ . Health 24, 107-114 (1972) .
19 .
S . D . COHEN
and S . D . bîUI~PHY, Proc . Soc . Lxp. Biol . Iled .
1385-138 9 (1972) . 20 .
~ . D . O'B~IEN, in Insecticides Action and t~letabolismi p15 (Academic Press, New York anà London, 1967),
Perga.mon Press
A L`Vf? A?YLAMIDASP; EXmäEb1F.L Y S:'sNSI'f~IVE ^C O~GANOPHOSPH04U~ COMP(IUNUS * TetsUO SStoh Toxicity Laboratory, DepaL~tment of Pharmacology, University of Chicago, Chicago, Illinois 6063
(Received 14 June 1973 ; in final form 24 September 1973) Summary
Inhibitory effect of 7 organophosphorus compounds on the liver isocarboxazid amidase was studied in rats . This enzyme is more sensitive to the relatively leas toxic compounds, i .e ., Sumithio , mala .thion and TOTP than to the more toxic ones such as pai"athicn, paraoxon and EPN . As little as 0.5 mg/kg of Sumithian inhibited this arylamidase activity by approx . 28gß in male and 37 ;~ in female rata . TOTP completely inhibited the arylamidase in e dose of 20 mg/kg, moreover, a significant sex difference in the TOTP-induced inhibition of the enzyme was observed . Organophosphorus insecticides are known to inhibit the activity of a number of esterases (1-~) besides cholinesterase . In a previous paper" (6) the present author showed that a liver arylamidase which is referred to as isocarboxazid (ISOC) amidase, was more susceptible to EPN than cholinesterase . IS OC is a monoamine oxidase inhiEit.or and is hydrolyzed by this arylamidase to produce benzylhydrazine . This amidase is responsible for the hydrolysis of several compounds possessing amido bonding and its molecular weight was estimated to be about 220,000 (~) The purpose of the present study was to examine the effects of 7 organophosphorus compounds on ISOC amidase in vivo .
* Present addressi Department of Pharmacology and Toxicology, Institute of Food Microbiology, Chiba University, Naraehino, Chiba, Japan.
1]82
]nsecticides and Liver Arylamidase
Vol. 13, No. 9
b~aterials and Methods Adult male and female Holtzman rats were used . They were fed Rockland rat diet ad libitum and maintained in an air-conditioned room at 68 ° -75 ° F . Compounds used here were obtained from the following sources
parathion and malathion (95°~) from American
Cyanamid Co ., Princeton, N .J .~ paraoxon from Dionsanto Chemical Co ., St Louis, Mi .t EPN (recrystallized "pure") from E . I . du Pont de Nemours & Co ., iNilmington, Del i sumithion from Chemargo Co^p . . Kansas City, Mo .~ Fole~Y'from Virginia-Carolina Chemical Corp .+ TOTP from Eastman Chemical Co ., Rochester, N . Y . Chemical structures of these compounds an3 their LD50 values are shown in Table 1 . Animals were sacrificed by decapitation and enzyme activity after incubation under the conditions described in the legend of Table 2 was stopped by adding 2 ml of 1$9~ metaphosphoric acid . After standing 10 min, the mixtures were centrifuged and an aliquot of the supernatant solution was removed to another test tube containing 0 .5 ml of redistilled water . Colorimetric assay of benzylhydrazine formed from ISOC waa carried out at 490 nm by adding 1 .5 ml of p-dimethylaminobenzaldehyde (PDAB) solution freshly prepared by dissolving 1 g of PDAB in 30 ml of ethanol and 15 ml of glacial acetic acid . This is a alight modification of the procedure used in preceding studies (12-14) . Results and Discussion Animals were administered single i .p . injection of sublethal doses of organophosphorus compounds . In no case were visible signs of poisoning observed . Table 2 shows the results of these experiments . Enzyme activities of 80 male and 92 female control rats were 0 .60 .024 and 0 .4610 .038
mole benzylhydrazine/50 mg
Vol . 13, No. 9
Jnsecticides and Liver Arylamidase
1183
0 w Cu
X
C]
v2 ô v
.~L.' a
â
Insecticides and Liver Arylamidase
1 ~ 84
Vol. 13, No . 9
liver wet wt ./30 min, respectively . The differences between the activities of the two sexes were significant (P<0 .01) as indicated by Student's t test . It is clearly recognized that this enzyme is more sensitive to the relatively less toxic compounds,
i .e ., sumithion,
malathion, TOTP than to the more toxic ones such as parathion, paraoxon and
PN . As little as 0 .5 mg/kg of sumithion which is
approximately 1 .3 x 10 -3 x LD50 (see 'fable 1), inhibited the liver arylamidase activity by approximately 28 ;b in male and 37îô in female rats . In addition, the existence of a sex difference in the cases of parathion, paraoxon and EPN can be explained by the correlation with the drug metabolizing enzyme activity associated with detoxification of these insecticides . The most interesting inhibitor in this study is TO'^P . This compound has been widely used as plasticizes and it completely inhibited ISOC amidase in a dose of 20 mg/kg which corresponds to approximately 1/125 of the LD50 . moreover, a significant sex difference in the TOTP-induced inhibition of the arylamidase was observed . Casida et al . (15) and Sharma and Watanabe (16) reported that the metabolism of TOCP(TOTP) involved hydroxylation followed by cyclization and elimination of one cresyl group. Since the first reaction depends on the liver microsomal drug metabolizing enzymes, the sex difference in the inhibitory effect of TOTP on the arylamidase can be explained by the known sex difference in the activity of the drug metabolizing enzymes . From these results the cyclized compound, not TOTP itself, is expected to be the actual inhibitor . In contrast, Murphy et al .(11) ^sported that no tissue cholinesterases wei~e inhibited even at larger doses of TaTP (110 mg/kP) or malathion (150 mg/k,.r) than +,hose used here .
Vol . 13, No . 9
1185
Insecticides and Liver Arylamidase TABLE 2 Inhibition of Liver Arylamidase in vivo by Organophosphorus compounds
Compound s
Dose (mg/k~; i . p . )
Amidase activityb Male
Fema e
M/F ratio
Per cent of Control s Parathion
Paraoxon
0 .05
90 .8±7 " 58 (6)
77 .4±1 .69 (7)
1,18
0,2
81 .0±6,57 (_5)
66 .917 .42 (7)
1 .21
0 .4
35 .1±4 .40 (5)
18 . ~ 2 .01 (5)
1 .90
0 .8
2 .1'0 .87 (5)
1 .110 .52 (6)
2 .08
106 .019,81 (5)
60 .717 .05 (5)
1 .75
0 .2
73 .5 8 .51 (5)
32 .2=3 .78 (5)
2 .28
0 .4
32 .314 .07 (5)
14 .0l1 .90 (5)
2 .30
3 .010 .69 (5)
1 .2-0 .48 (5)
2 .50
0 .4
79 .712 .27 (5)
77 .516 .70 (6)
1 .03
1 .0
46 .8±2 .77 (6)
42 .715 .95 (5)
1 .10
4,0
4 .111 .12 (_5)
1 .910 .32 (5)
2 .16
0,05
o .s FP^;
a All animals were sacrificed at 3 hr after injection, b FiFUres in paranthese indicate number of animals used . c Data expressed as MeanlS .i . Compounds were dissolved in 20°~ e+hanol and 80°ô propylene glycol and administered i .p . The concentrations of the solutions of the compounds were adjusted so that the volume of injections was 1 ml/kg of body weight . Control animals were liven an equivalent volume of the vehicle, Incubation mixtures consisted of 0 .5 ml of 10;" liver homogenate, 0 .5 ml of redistilled water and 0 .5 ml of the substrate solution which was prepared by dissolving 3 .0 ~Zmoles isocarbexazid in 0,1 M phosphate buffer (pH 7 .4), Incubation time was 30 min at 37 oC and the enzyme activity was assayed as described in the ±ext,
Insecticides and Liver Arylamidase
1188
Vol. 13, No . 9
TABLE 2 (Continued) Fole~
Sumithior~
Malathion
TOTP
1
58 . 2t 7 . 61 (5)
49 . ~ 3 . 82 (5)
1 .17
5
16 .7t1 .o4 (6)
11 .4~ 0,96 (6)
1 .46
l0
4 .oto .89 (5)
4,oto,45 (5)
1 .00
20
1 .5±0 .22 (5)
1 .8to,5o (5)
0,83
0 .5
72 .0±0,78 (5)
63,2~3,55 (5)
1 .14
2
57 .2±2 .98 (5)
49 .4±5 .95 (5)
1 .16
l0
4o .5t5 .17 (5)
34 .0±2 .75 (6)
i .ly
50
38 .3±1 .59 (6)
31 .2±2 .62 (6)
1 .23
100
32 " 311 .26 (5)
18,611 .7` (5)
1 .74
2
77 .6±2 .71 (8)
100,bt 7 .72 (6)
0 .77
l0
49 .9±4 .35 (7)
50 .6±5 .65 (6)
0 .98
.50
29 .8±1 .71 (5)
26 .4±7 .44 (5)
1 .12
l00
15 .6±1 .78 (6)
15 .~+1 .29 (5)
0 .99
1
63 .2t5 .09 (9)
69 .01 2 .20 (7)
0 .92
5
16 .514,18 (8)
42 .x+1 .90 (9)
0 .39
10 20
1,7±0 .39 (5) 0.0±0 .00 (5)
22 .E 1 .42 (5) 2 .010 .43 (5)
0 .07 0 .00
On the other hand, it is known that all organophosphorus insecticides can be dealkylated to some extent by liver microsomal mixed function oxidase (17) . This reaction seems to be closely correlated with the inhibition of the liver arylamidase in this study, because p-nitrophenyl phosphoric acid :showed no inhibition even at 10~ Ivi in an experiment in vitro (not presented here) . The data shown in Table 2 demonstrate that the antiamidase activity is associated with the alkyl substitutions (?1 and R 2 in Table 1) .
Toxicities for insects as well as for mammals which have
Vol. 13, No . 9
Insecticides and Liver Arylamidase
1187
been reported closely parallel the inhibitory effects of oreanophosphorus compounds on ISOC amidase . Recently, I+lurphy and co-workers (18,19) proposed that inhibition of carboxylesterase by malathion is due to an irreversible binding to the enzyme . Moreover, detoxification of or~anophosphorus insecticides may be attributed to the bindinP of these compounds to a protein molecule other than cholinesterase . 'T'his mechanism is exactly applicable to the present study, because it is known ±hat the esterification of p-nitrophenyl phospho!°ic acid to parathion, paraoxon or ~P^I produces a marked change in the electronic nature of the phosphorus (20) and consequently, this reaction greatly increases both the anticholinesterase activi+,y an3 toxicity of~the compound . `!'his fact su~eests ±hat `he affinity of ~.he or~anophosphorus compounds for the protein molecule is dependent. upon the alkyl stoups of the compounds . Further studies on the mechanism of the effects described here a^e now in pro?ress . Acknow,led~-ment-?'he author dedicates this paper to the memory of Professor 'r,_enneth P . UuDois .
Isocarboxazid was kindly donated
by fof.fTann-La ',oghe Inc ., futley, ^'ew Jersey . Rsferences 1.
'r; . P . UuH07S, F . I: . ICIROSHI~nA and J . P . F?A'NI rY, Toxicol . Appl . Pharmac ol . 12, 273-284 (1968) .
2.
C . :-! . ~NILIiI:i'~:S and K . H . JACCBSO":, Toxicol . Appl . Pharmacol . , 40~-500 (1966) .
3.
J .~ . CASIUA, Biochem . Pharmac . ~, 332-342 (1951) .
4.
I . ". . FLUCt.HA~'_" and J . E . CASIDA, Biochem . Pharmac . 21, a_5y1-26o3 (1972) .
5.
F . iN . SFUMF and '. . D . U'B?I~:N, A~r . Food Chem . 8, 36-41(1960) .
Insecticides and Liver Arylamidase
]188
Vol . 13, No . 9
6.
T . SATOH and K . MO?OI, Toxicol . Appl . Pharmacol . in press .
7.
T . SATOH and K . MOEOI, Biochem . Pharmac . 21, 3111-3120 (1972) .
8.
Y . PdISI?IZAiNA, K . FUJII, T . u.ADOmA, J . :~îIYAY0T0 and H . SAI~~Abî0T0, A~r . Biol . Chem . (Tokyo) ~, 605-610 (1961) .
9. 10 .
Y. . P . DuBOIS, Bull . Wld . Hlth . OrP, 44, 233-240 (1971) . -. . H . D~fISHAC~i, Handbook of Poisonin~~ :~ia~nosis and Treatment, p104, Lan#e Med . Publ ., Los Altos, Calif ., 1971 . S.
T~ .
hiU~fPl?Y, ~ . L . ANO .°.50~' and _ . P . DuBGIä, Proc~3oc .
Exp . Biol . N~ed . 100, 483-487 (1y59) . 12 .
T . âATCH and K . MOROI, Anal . Chim . Acta 51, 449-454 (1970) .
13 .
T . SATOH and K . MUrOI, Biochem. Pharmac . 20, 504-507 (1971) .
14 .
T . SATOH and K . iv10?OI, Life Sci . 12, 169-175 (1973) .
15 .
J . E . CASIDA, M (1961) .
16 .
? . P . SHA3h~A and P . G . WATANABE, in Abstrac's of papers, T~ti~elfth Annual fdeetin; of Society of Toxicolo^y . p89 (Academic P_,ess, New Yo .-^k and London, 1973) .
17 .
C . DIN~dINs=,~, D . ?i . HU':SON and B . A . PICK°.°.I~+s, Bi :~chem, .7 . 126, 701-707 (1972) .
1.3 .
S . D . f.;U?PHY and Y, . L . C~EE'J'L'", Arch . Environ . Health 24, 107-114 (1972) .
19 .
S . D . COHEN
and S . D . bîUI~PHY, Proc . Soc . Lxp. Biol . Iled .
1385-138 9 (1972) . 20 .
~ . D . O'B~IEN, in Insecticides Action and t~letabolismi p15 (Academic Press, New York anà London, 1967),