Inhibition of oligomycin-sensitive (mitochondrial) Mg 2+ ATPase by DDT and selected analogs in fish and insect tissue

Kelthane residues in tissues of the tropical penaeid prawn, Metapenaeus monoceros (Fabricius), under sublethal chronic exposure--a monitoring study

Monitoring the biodegradation and bioaccumulation of kelthane residues were undertaken during reclamation through oxygen consumption (respiration) and target enzyme activity assays. Even after 30 days of reclamation, non-recovery in respiration and target enzyme assays revealed the accumulation of kelthane as a residue in tissues. Thin-layer chromatography demonstrated the presence of kelthane residues as spots in tissue extracts of midgut gland and muscle after a 30-day recovery period. This confirms that kelthane is a persistent insecticide of low biodegradability and capable of accumulating in tissues as residues even at sublethal concentration under chronic exposure.

Effects of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT) on ATPase-linked functions in isolated rat-liver mitochondria

The effects of DDT on the energy-related functions of rat-liver mitochondria were examined. ADP-stimulated respiration was much more sensitive to inhibition by DDT than was uncoupler-stimulated respiration when succinate or ascorbate/TMPD was used as the substrate. Ca2+ uptake driven by ATP hydrolysis was inhibited by DDT. These results indicate that DDT inhibits ATPase itself. In addition, DDT blocked succinate dehydrogenase and the cytochrome b-c span of the electron transport chain, which also secondarily reduced ATP synthesis. The uncoupling action due to DDT was only seen at high concentrations with ascorbate/TMPD as the substrate. However, this action was masked because of the increased inhibition of the electron transport chain when the substrate was changed to succinate.

Effect of temperature on the inhibition of rat brain synaptosomal ATPases by DDT and its structural analogs

In vitro effects of DDT and its isomers or metabolites were studied on Na+-K+-ATPase and oligomycin-sensitive (OS) Mg++-ATPase activities at 17, 27 and 37 degrees C in rat brain synaptosomes. Dicofol and methoxychlor were found to be more effective inhibitors of Na+-K+-ATPase and OS Mg++-ATPase than DDT, DDD and DDE. Inhibition of OS Mg++-ATPase by the compounds tested (except DDE) was found to be greater at 17 degrees C than at higher temperatures (17 greater than 27 greater than 37 degrees C), suggesting a negative temperature correlation trend Na+-K+-ATPase was less sensitive to these compounds when compared with OS Mg++-ATPase and the inhibition was greater at higher temperatures (37 greater than 27 greater than 17 degrees C), suggesting a positive temperature correlation trend. Other DDT isomers and metabolites showed variable effects on Na+-K+-ATPase and OS Mg++-ATPases. DDD, but not DDE, inhibited both enzyme activities and the inhibition was independent of temperature. No significant differences were observed in the inhibitory potencies of the various DDT, DDD or DDE ring substitutes studied. The present data indicate that DDT, dicofol and methoxychlor were more effective inhibitors of OS Mg++-ATPase than Na+-K+-ATPase and that the inhibition of the former enzyme had a negative temperature dependence, a feature which parallels toxicity results in insects.

In vivo effect of mercuric chloride on tissue ATPases of Notopterus notopterus

Effect of sublethal concentrations, 0.088, 0.044, 0.029, 0.022 and 0.0176 mg HgCl2 per liter (1/5, 1/10, 1/15, 1/20, and 1/25 fractions of 96-h LC50) on Na+-K+, Mg2+, and total ATPase activities in brain, gills, kidney and liver of Notopterus notopterus have been studied after 30 days exposure. Na+-K+ ATPase were inhibited maximally and significantly in brain and minimally and insignificantly in liver. Mg2+ ATPase was inhibited maximally and significantly (P less than 0.01) in brain and minimally and insignificantly in kidney. The relative inhibition of total, Na+-K+ and Mg2+ ATPases for the tissues studied were brain greater than gill greater than kidney greater than liver. At the concentration (1/25 fraction) the enzyme activity returned to the normal range.

Effects of dichlorodiphenyltrichloroethane and its analogues on rat liver mitochondria

The effects of dichlorodiphenyltrichloroethane (DDT) and sixteen analogues on respiration, swelling and latent ATPase of rat liver mitochondria were examined systematically. The compounds tested could be divided into four groups: DDT-type, DDE-type, kelthane-type and others by substituent groups on the ethane bridge of bis(p-chlorophenyl) ethane. Most compounds tested were shown to inhibit State 3 respiration. A linear relation was observed between the logarithms of the concentrations giving half-inhibition of State 3 respiration and the logarithms of the partition coefficients of the tested compounds. Four compounds of the kelthane type and chlorobenzilate stimulated State 4 respiration to the level of dinitrophenol-stimulated respiration. The compounds that have a hydroxy group on the ethane bridge-rapidly induced mitochondrial swelling, but DDT-type and DDE-type compounds induced swelling when the suspension contained 0.15 M KCl and 5 mM Tris-HCl. Latent ATPase of mitochondria was stimulated to different maximum levels by each of the tested compounds except DDA. The oligomycin-sensitive ATPase of submitochondria was inhibited by a series of kelthane-type compounds.

Inhibition of the active transport of D-glucose and L-tyrosine by DDT and DDE in the rat small intestine

1. The effect of DDT and DDE on the active transport of D-glucose and L-tyrosine was studied in everted sacs of small intestine. 2. DDT and DDE (10(-5) and 10(-4) M) inhibit the active transport of D-glucose and L-tyrosine. 3. These organochlorine compounds also inhibit the (Na+ + K+)-ATPase from the same tissue, to about the same extent. 4. These results suggest that the inhibition of the active transport is due to an action of DDT and DDE on the sodium pump.

Adenosine triphosphatase activity in few tissues of a fresh water teleost, Channa gachua following in vivo exposure to endosulfan

Fresh water teleost fish, Channa gachua, were chronically exposed to various sublethal concentrations of endosulfan (0.00534, 0.00355, 0.00213 and 0.00174 mg/1) at 25 +/- 4 degrees C for 30 and 60 days respectively. The study shows enzyme inhibitions, greatest in oligomycin-insensitive Mg2+ ATPase in brain, gill and liver tissues, with pronounced effects at highest endosulfan concentration for 60 days exposure. However, in kidney the highest inhibition was of oligomycin-sensitive (mitochondrial) Mg2+ ATPase. The study indicates that endosulfan interferes with energy metabolism in vivo. The marked sensitivity of mitochondrial Mg2+ ATPase to endosulfan is suggestive of the potential for endosulfan to interfere markedly with various energy requiring processes in the fish body.

In vitro disruption of ATP dependent active transport following treatment with aldrin and its epoxy analog dieldrin in a fresh water teleost, Labeo rohita

Tissue homogenates of brain, gill, liver and kidney of Labeo rohita were subjected in vitro to the various concentrations as 5.00, 1.66, 0.55, 0.18 and 0.06 mu M of 2 organochlorine pesticides aldrin and dieldrin and the disruption of ATP dependent active transport (involving ATPase) was studied. The inhibition of total ATPase, Mg2+ and Na+, K+-dependent ATPase by both the pesticides was quite similar and there was an increased inhibition with increased concentration of the toxicant, however, at the lowest concentrations of both the pesticides stimulation was observed in all tissues except gill Mg2+ ATPase where insignificant inhibition was observed after dieldrin treatment. Inhibition of ATPase system was noted maximum in brain followed by gill, kidney and liver of the experimental fish, however in each tissue maximum inhibition of ATPase was noted after dieldrin treatment than that of th e aldrin treatment. Therefore, the observed action of these pesticides might be related to the ability of the compounds to alter the cellular membrane configuration by binding with the lipid portion of the membrane and this blocking the movement of substances by active transport.

The mode of action of p,p'=DDT on mammalian mitochondria

In rats treated with single, sublethal doses of p,p'-DDT oxidative phosphorylation efficiency, respiratory activity and "latent" ATPase activity in liver and brain mitochondria were determined. A time- and dose-dependent decrease in oxidative phosphorylation efficiency was found. Time-dependent suppression of respiratory activity in state 3 was noticed and a stimulation of mitochondrial ATPase activity 24 h after DDT treatment in liver and brain mitochondria was found. The correlation between time-dependent changes in the brain mitochondrial fraction and distribution of DDT in brain after a single, oral dose is discussed. It is suggested that changes in mitochondria were caused by DDT and its metabolites. It is concluded that the uncoupling of oxidative phosphorylation especially in brain mitochondria could be responsible for some DDT intoxication symptoms in mammals.