Thiols and polyamines in the potentiation of malathion toxicity in larval stages of the toad Bufo arenarum.
Treatment with exogenous spermidine enhanced acute malathion toxicity during larval development of the toad Bufo arenarum Hensel. The polyamine was rapidly incorporated in the larvae with a subsequent metabolization to putrescine and spermine, which were excreted to the media. Endogenous polyamine levels were not changed by either spermidine or malathion treatments. However, 0.5-mM spermidine modified malathion uptake and bioavailability increasing the concentration of the xenobiotic in the larvae. The amount of reduced thiols was decreased by both compounds, but the depletion was insufficient to induce cytotoxicity. The oxidative degradation of polyamines competes for the pool of reduced glutathione used in the conjugation of malathion in the larvae, thus leading to the reported potentiation of toxicity. Our results suggest that exposure to thiols-depleting agents may induce alteration of organophosphate degradation in amphibian larvae.
Venturino
A
A
LIBIQUIMA, Universidad Nacional del Comahue, Buenos Aires 1400, 8300, Neuquén, Argentina.
Anguiano
O L
OL
Gauna
L
L
Cocca
C
C
Bergoc
R M
RM
Pechen de D'Angelo
A M
AM
D000818:Animals; D001682:Biological Availability; D001711:Biotransformation / Q000187:drug effects; D002022:Bufo arenarum / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D019803:Glutathione Disulfide / Q000187:drug effects; D007814:Larva / Q000187:drug effects; D015227:Lipid Peroxidation / Q000187:drug effects; D008294:Malathion / Q000493:pharmacokinetics / Q000633:toxicity*; D010084:Oxidation-Reduction; D010574:Pesticide Synergists / Q000493:pharmacokinetics / Q000494:pharmacology*; D013095:Spermidine / Q000493:pharmacokinetics / Q000494:pharmacology*; D013438:Sulfhydryl Compounds / Q000378:metabolism*
D010574:Pesticide Synergists; D013438:Sulfhydryl Compounds; D008294:Malathion; D013095:Spermidine; D019803:Glutathione Disulfide