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PubMed1991

Differences in the mode of lethality produced through intravenous and oral administration of organophosphorus insecticides in rats.

This study was undertaken to investigate the possibility that mechanisms other than cholinesterase (ChE) inhibition account for the acute toxicity of organophosphorus insecticide. Both the P = O type insecticide (direct ChE inhibitors: chlorfenvinphos and dichlorvos) and the P = S type insecticide (indirect ChE inhibitors: diazinon and fenthion) were employed. Rats treated with lethal doses of intravenous and oral P = O type insecticides and oral P = S type insecticides exhibited typical signs of anti-ChE poisoning along with marked inhibition of brain and erythrocyte ChE activity. In contrast, rats given lethal doses of intravenous P = S type insecticides exhibited tonic convulsions and opisthotonos, with only slight inhibition of ChE activities. When P = O type insecticides were intravenously administered to anesthetized and conscious rats, animals exhibited typical anti-ChE poisoning signs in cardiorespiration: hypertension and apnea which were antagonized by atropine. After administration of lethal doses of P = O type insecticides, breathing disappeared before the cessation of heart beats. Rats receiving lethal doses of intravenous P = S type insecticides did not show hypertension, but exhibited transient cessation of breathing and heart beats. Breathing was observed after the disappearance of heart beats. The electroencephalogram (EEG) was characterized by spike and wave complexes. The EEG and cardiorespiratory changes were not antagonized by atropine. It was concluded that lethality following intravenous P = S type insecticides may be independent of ChE inhibition.

Administration, Oral↗
PubMed1975

Uptake and excretion of organophosphorus and carbamate insecticides by fresh water fish, motsugo, Pseudorasbora parva.

Fresh water fish, Motsugo was reared in aquarium water tank containing about 1 ppm of 3 organophosphorus and 3 carbamate insecticides for about 30 days. The persistence of these insecticides in water and uptake and excretion of insecticides by fish were examined. Among organophosphorus insecticides, malathion is the most unstable in water, and degraded more than 99% for 7 days. Fenitrothion is moderately stable, and degraded 97% for 29 days. Diazinon is the most stable, and degraded 72% for 30 days. Among carbamates, carbaryl is the most unstable in water, and degraded more than 95% for 6 days. BPMC is moderately stable, and degraded 80% for 32 days. XMC is the most stable, and degraded 45% for 34 days. As for the uptake of the pesticides by fish, organophosphorus insecticides were generally higher than carbamate insecticides. The concentration of diazinon in fish reached to 211 ppm of the maximum level after 3 days, and that of fenitrothion reached to 162 ppm of the maximum level after 4 days. Afterwards, the concentration of both the insecticides decreased gradually due to the metabolism and excretion of the insecticides in fish. Uptake of malathion was very low and metabolized rapidly, and its concentration became to less than 0.01 ppm after 7 days. Among carbamate insecticides, the concentration of carbaryl in fish after one day reached to 7.5 ppm which was the maximum level of uptake. On the other hand, the concentration of BPMC in fish after 4 days became to 4.8 ppm, which was the maximum level, and decreased gradually. The concentration of XMC in fish was only 1.4 ppm after one day, but the metabolism rate of XMC in fish was fairly slow. Therefore, 0.55 ppm of XMC in fish remained even after 34 days. Moreover, in the test tank of diazinon, fenitrothion and BPMC, the appearance of deformed fish with spinal curvature of back bone came out at the rate of 10 to 30%.

Animals↗
PubMed1988

A comparison of the persistence in a clay loam of single and repeated annual applications of seven granular insecticides used for corn rootworm control.

In May 1983, granular formulations of carbofuran, chlorpyrifos, disulfoton, fonofos, isofenphos, phorate, and terbufos were applied in incorporated bands to duplicate 2 m2 field plots of clay loam. Insecticide concentrations were determined in the bands at 0,1,2,3,4,6,8,10,12,16, and 20 wk. Following spring cultivation, the insecticides were applied to the same plots in 1984 and 1985. In addition, carbofuran was applied to previously untreated plots in 1984 and all 7 materials were applied to previously untreated plots in 1985. Sampling and analysis were carried out as in 1983. Persistence was assessed on the basis of the disappearance rates measured for the 1st 8 wk and of a calculated Effectiveness Potential (the ratio of the average residue in the upper 5 cm of the band at 8, 10 and 12 wk and the published LC95 for western corn rootworm in clay loam soil). Soils treated with carbofuran and isofenphos in 1984 and all soils treated in 1985 were tested for anti-insecticide activity. Soil cores from some carbofuran, chlorpyrifos and terbufos treated plots were sectioned vertically to establish the distribution of the insecticides during 1985. In addition, granular and pure chemical forms of isofenphos and carbofuran were applied at 10 ppm to anti-isofenphos and anti-carbofuran active and control soils (from field plots) maintained at 10 and 20% moisture in the laboratory to assess the effect of formulation and moisture on persistence in active soils. Insecticide concentrations were determined at 0,1,3,7, 10,14,21,28, and 35 days. The persistence of chlorpyrifos, terbufos and phorate was relatively constant over the 3 years and between plots receiving single and multiple treatments. Disulfoton and fonofos behavior was more variable and that of carbofuran and isofenphos was extremely variable. Anti-insecticide activity against carbofuran and isofenphos was detectable 2 wk after an initial application and was still present the following spring. Anti-insecticide activity against fonofos, terbufos sulfoxide, phorate sulfone and disulfoton sulfone was also generated in this soil. Anti-insecticide activity against chlorpyrifos, disulfoton, terbufos and phorate was not present. Carbofuran, chlorpyrifos and terbufos (+ metabolites) present in the upper 5 cm of soil averaged 93, 94 and 94%, respectively, of the total core contents over 12 wk. Significant moisture dependent differences were observed between the behavior of granular carbofuran and granular isofenphos in anti-insecticide active soils.(ABSTRACT TRUNCATED AT 400 WORDS)

Chromatography, Gas↗
PubMed1988

Pyrethroid insecticides and DDT modify alkaloid-dependent sodium channel activation and its enhancement by sea anemone toxin.

The effects of saturating concentrations of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] and the pyrethroid insecticides cismethrin and deltamethrin on alkaloid-dependent activation of the voltage-sensitive sodium channel were studied using measurements of 22Na+ uptake into mouse brain synaptosomes. In survey experiments, these compounds enhanced sodium uptake stimulated by veratridine and batrachotoxin, but inhibited uptake stimulated by aconitine. Concentration response curves for aconitine run in the absence and presence of 10 microM cismethrin demonstrated that the inhibition was noncompetitive. This unanticipated inhibitory effect of insecticides on aconitine-dependent sodium uptake suggests a possible overlap or negative allosteric coupling between the binding sites for insecticides and aconitine and reveals unique characteristics of the action of aconitine that are not shared by veratridine and batrachotoxin. More detailed studies of the effects of insecticides on veratridine- or batrachotoxin-stimulated uptake found small insecticide-dependent increases in the potency of these activators. In addition to this effect, DDT and deltamethrin also enhanced maximal uptake stimulated by veratridine. Possible mechanisms underlying these effects of insecticides on alkaloid-dependent uptake are discussed in light of a qualitative model formulated from these results and previous biochemical and electrophysiological studies. Additional experiments were designed to assess the interactions of insecticides and toxin II of the sea anemone Anemonia sulcata (ATX II) as modifiers of alkaloid-dependent uptake. DDT and ATX II acted synergistically to increase uptake stimulated by veratridine. Moreover, DDT shifted the potency of ATX II for enhancing veratridine-dependent uptake to 5-fold lower concentrations. In contrast, DDT and subsaturating concentrations of ATX II acted independently in their enhancement of sodium channel activation by batrachotoxin. Mutually exclusive effects on veratridine-dependent uptake were observed when cismethrin was co-applied with ATX II. However, independent effects of cismethrin and ATX II were found with aconitine-modified channels, in that cismethrin was able to inhibit ATX II-enhanced aconitine-dependent sodium flux. Thus, the interactions between insecticides and ATX II as modifiers of alkaloid-dependent uptake are complex and depend on the insecticide-activator combination under study.

Aconitine↗