The site of inhibition of porphyrin biosynthesis by an isomer of diazinon in rats

Nichol, A. W.; Elsbury, Susan; Angel, Lyndall A.; Elder, George H.

doi:10.1016/0006-2952(83)90071-0

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…In addition, several pesticides were found in the present study to be generally ineffective in inhibiting RBC ALA-d enzyme activity. Similarly, chronic Dz exposure did not alter hepatic ALA-d activity in rats even though other enzymes of the heme biosynthetic pathway were affected [30]. Although these findings do not guarantee that pesticides or their metabolites will not affect ALA-d activity after in vivo exposure, it does indicate a lack of direct inhibition of the enzyme by pesticides as well as a lack of interference by pesticides in the assay of ALA-d activity.…”

Section: Discussionmentioning

confidence: 75%

“…Furthermore, large excesses (2-3 orders of magnitude) of Dz, Cb or HCB had little or no modulating influence on the inhibitory potency of Pb2+. Nevertheless, in light of the porphyrinogenic properties of some pesticides and other organic chemicals [29,30,38,39], further studies are warranted to determine the in vivo effects of these substances on avian ALA-d, and their interactions with Pb. High doses of HCB in vivo (0.3% of diet for 8 weeks) caused minor (20-23%) declines in RBC and hepatic ALA-d in rats, but hepatic ALA synthetase was affected to a much greater extent, showing increases of 175 to 260% [38].…”

Section: Discussionmentioning

confidence: 99%

“…Two of these pesticides (Dz, HCB) are known to interfere with in vivo heme biosynthesis in mammals [29,30]. Triangle Park, NC; 99.9% purity) and carbofuran (Cf) (FMC Corp., Princeton, NJ; 96% purity).…”

Section: Pesticides In Vitromentioning

confidence: 99%

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Effects of lead and pesticides on δ‐aminolevulinic acid dehydratase of ring doves (Streptopelia risoria)

Scheuhammer¹,

Wilson²

1990

Enviro Toxic and Chemistry

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The effects of lead (Pb2+) and various pesticides on δ‐aminolevulinic acid dehydratase (ALA‐d) in avian blood, liver and kidney were studied. In blood, virtually all of the ALA‐d activity was localized in the cellular fraction. Complete inhibition of RBC ALA‐d occurred at an in vitro Pb2+ concentration of ∼10 μmol/g protein, with an IC50 of ∼0.9 μmol/g protein. Pesticides (carbaryl, carbofuran, chlorpyrifos, diazinon, dieldrin, fenitrothion, hexachlorobenzene) added to blood samples up to 10 mM in vitro had no inhibitory effect on ALA‐d, nor did the presence of pesticides greatly modify the response of ALA‐d to inhibition by increasing concentrations of Pb2+. Recovery of Pb‐inactivated RBC ALA‐d activity was accomplished by treatment of blood hemolysates with Zn2+ and an SH‐reducing agent such as dithiothreitol (DTT). A combination of Zn2+ (4 mM) and DTT (120 mM) was required to achieve complete recovery of Pb‐inhibited enzyme activity. Normal avian ALA‐d activity was greatest in blood, followed by liver, then kidney. Unlike blood hemolysates, liver and kidney homogenates contained a fraction of ALA‐d activity which was very resistant to inhibition by in vitro Pb2+. In vivo, hepatic ALA‐d was unaffected by Pb exposure (2.5 μg Pb2+/g body weight injected intraperitoneally), but renal ALA‐d was decreased as a result of greater deposition of Pb in kidney than in liver. Inhibition of ALA‐d in avian blood, particularly when expressed as a ratio of fully restored:nonrestored activity (activity ratio), is a highly specific, sensitive indicator of Pb exposure, deposition and corresponding enzyme inhibition in other target organs (kidney).

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Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

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Effects of lead and pesticides on δ‐aminolevulinic acid dehydratase of ring doves (Streptopelia risoria)

Scheuhammer¹,

Wilson²

1990

Enviro Toxic and Chemistry

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show abstract

“…In vivo studies with pesticides are not a part of the present report; however, a preliminary experiment in which ring doves were dosed orally with Dz (0.5 mg/kg/day for two consecutive days) revealed that RBC ALA-d activity was not depressed 24 h after the final dose (Scheuhammer, unpublished data, August 1988). Similarly, chronic Dz exposure did not alter hepatic ALA-d activity in rats even though other enzymes of the heme biosynthetic pathway were affected [30]. Nevertheless, in light of the porphyrinogenic properties of some pesticides and other organic chemicals [29,30,38,39], further studies are warranted to determine the in vivo effects of these substances on avian ALA-d, and their interactions with Pb.…”

Section: Discussionmentioning

confidence: 95%

“…To test whether the presence of pesticides in blood could modify the response of ALA-d to Pb2+, ALA-d activity was measured after addition of 0 to 0.1 pmol Pb2+/ml blood, in the presence of water (control), or 10 pmol/ml Dz, Cb or HCB. Two of these pesticides (Dz, HCB) are known to interfere with in vivo heme biosynthesis in mammals [29,30].…”

Section: Pesticides In Vitromentioning

confidence: 99%

EFFECTS OF LEAD AND PESTICIDES ON (Δ-Aminolevulinic ACID DEHYDRATASE OF RING DOVES (STREPTOPELIA RISORIA)

Scheuhammer¹,

Wilson²

1990

Environ Toxicol Chem

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The effects of lead (Pb2+) and various pesticides on 8-aminolevulinic acid dehydratase (ALA-d) in avian blood, liver and kidney were studied. In blood, virtually all of the ALA-d activity was localized in the cellular fraction. Complete inhibition of RBC ALA-d occurred at an in vitro Pb2+ concentration of -10 pmol/g protein, with an IC50 of -0.9 pmol/g protein. Pesticides (carbaryl, carbofuran, chlorpyrifos, diazinon, dieldrin, fenitrothion, hexachlorobenzene) added to blood samples up to 10 mM in vitro had no inhibitory effect on ALA-d, nor did the presence of pesticides greatly modify the response of ALA-d to inhibition by increasing concentrations of Pb2+. Recovery of Pb-inactivated RBC ALA-d activity was accomplished by treatment of blood hemolysates with Zn2+ and an SH-reducing agent such as dithiothreitol (DTT). A combination of Zn2+ (4 mM) and DTT (120 mM) was required to achieve complete recovery of Pb-inhibited enzyme activity. Normal avian ALA-d activity was greatest in blood, followed by liver, then kidney. Unlike blood hemolysates, liver and kidney homogenates contained a fraction of ALA-d activity which was very resistant to inhibition by in vitro Pb2+. In vivo, hepatic ALA-d was unaffected by Pb exposure (2.5 pg Pb2+/g body weight injected intraperitoneally), but renal ALA-d was decreased as a result of greater deposition of Pb in kidney than in liver. Inhibition of ALA-d in avian blood, particularly when expressed as a ratio of fully rest0red:nonrestored activity (activity ratio), is a highly specific, sensitive indicator of Pb exposure, deposition and corresponding enzyme inhibition in other target organs (kidney).

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Teratogenic Effects of Organophosphorus Compounds

Kitos

Suntornwat

1992

Organophosphates Chemistry, Fate, and Effects

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The site of inhibition of porphyrin biosynthesis by an isomer of diazinon in rats

Cited by 6 publications

References 12 publications

Effects of lead and pesticides on δ‐aminolevulinic acid dehydratase of ring doves (Streptopelia risoria)

Effects of lead and pesticides on δ‐aminolevulinic acid dehydratase of ring doves (Streptopelia risoria)

EFFECTS OF LEAD AND PESTICIDES ON (Δ-Aminolevulinic ACID DEHYDRATASE OF RING DOVES (STREPTOPELIA RISORIA)

Teratogenic Effects of Organophosphorus Compounds

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