Effects of disulfiram (DSF) on freshly isolated hepatocytes were examined. Its effects on the cellular reduced form of glutathione (GSH) were triphasic ; GSH decreased instantly after the addition of DSF, teturned to subnormal levels within 30 min, and then declined gradually. The initial decrease in GSH after DSF treatment and the subsequent recovery of GSH were accompanied by an increase and decrease in the oxidized form of gluiathione (GSSG), respectively. Decreases in cell viability brought about by 0.4 mM of DSF were correlated with the later gradual decrease in GSH. The loss of viability by DSF treatment seemed to appear when the intial GSH levels became lower than approximately 5 nmole/106 cells. Hepatocyte toxicity of DSF was potentiated by diethylmaleate (GSH depletor) and inhibited by N-acetylcysteine (GSH biosynthesis precursor). 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of GSH reductase, inhibited the GSH recovery and potentiated the toxicity. Respiration of hebatocytes was also inhibited by DSF. Free sulfhydryl groups other than GSH showed similar changes to those of GSH. From these results, it seemed that DSF reacted with cellular GSH and other free sulfhydryl groups to form diethyldithiocarbamate and GSSG, GSSG was feduced back to GSH by glutathione reductase, and the detrease in the viability was dependent on the initial loss of GSH.
The interaction of thinner and carbon tetrachloride (CCl4) induced hepatotoxicity was studied in the rats using the activity of plasma GOT and GPT, liver triglyceride and histopathologic changes of liver necrosis as indices. The animals were housed in a chamber with the continuous flow of thinner vapour (1.11 g/litre/hr) for 2 hrs prior to i.p. administration of CCl4 (0.1 ml/kg BW) at 18 hrs after thinner inhalation. Thinner inhalation potentiated CCl4 induced hepatotoxicity in a dosedependent manner. The maximal enhanced effect was observed at 24 hrs after CCl4 administration by which the activities of PGOT and PGPT were significantly increased (3 folds). Thinner itself caused an additive effect on CCl4 induced liver triglyceride accumulation. At 18 hrs after thinner inhalation, the activity of NADPH cytochrome C reductase was markedly increased (2.2 folds) but no change in the activity of aminopyrine N-demethylase which was able to increase the 14·CCl3 free radicals and binding to both the hepatic microsomal proteins (1.8 folds) andlipids (1.4 folds). In addition, thinner pretreatment somehow increased hepatic lipid peroxidation by 1.4 folds. These results suggest that thinner pretreatment causes an increase in mixed function oxidases to activate the formation of ·CCl3 free radicals and binding to the microsomal proteins and lipids, which in turn stimulate hepatic damage via lipid peroxidation in the membrane.
Electroretinographic changes induced by organophosphorus pesticides (OPs) were studied in rats. Male Wistar rats were intraperitoneally injected with fenthion, chlorpyrifos, fenitrothion, dichlorvos or chlorfenvinphos at doses of 0.01 mmol/kg and/or 0.05 mmol/kg. The electroretinogram (ERG) was retorded at 5 hours and 2 days after the administration, and brain and retinochoroid cholinesterase (ChE) activities was assayed at 3 days after the injections. The brain and retinochoroid ChE activities were reduced in rats treated with the OPs. Notably, the reduction of ChE activities by fenthion, chlorpyrifos and dichlorvos were similar. The administration of OPs induced a change in the ERG, characterized by alteration of the amplitudes of a- and b-waves. Nevertheless the ChE activities in the brain and retinochoroid were inhibited by all of the OPs, the OPs affected the amplitude of ERG differently. Fenthion and chlorpyrifos decreased the amplitudes ; dichlorvos and chlorfenvinphos increased ; and fenitrothion transiently decreased at 5 hours but incredsed 2 days after the injection. These results indicate that a factor or factors other than inhibition of ChE activities contributes to the alteration of ERG induced by OPs.
The effect of DL-ethionine (EthN) on the blood clearance of 99mTc-phytate (99mTc-p) in dogs was examined, and the blood clearance test of 99mTc-P was compared with the cases of the serum transaminase and bilirubin test. Serum transaminase and bilirubin levels in dogs increased dosedependently after the administration of EthN. The disappearance rate of 99mTc-p from blood in dogs decreased with the increase in dose of EthN and with the passage of time after EthN administration. Changes of the blood clearance of 99mTc-P after EthN treatment in dots may be influenced by the disorder in the hepatocytes. The blood clearance test of 99mTc-P in dogs showed a reaction for the acute hepatic dysfunction induced by EthN equally to the serum transaminase and bilirubin test.
An oral chronic toxicity study of propiverine hydrochloride (P-4), a new anti-pollakiuria agent, was carried out at dose levels of 0(control), 0.5, 5 and 50mg/kg/day using male and female rats. They were treated for 52 weeks, followed by 5 weeks recovery period. The results obtained from the present study were as follows. 1. There were no deaths related to P-4. Mydriasis, transitory salivation were observed in both sexes receiving 50mg/kg/day, and soil of the abdomen was also noted in females receiving 50mg/kg/day. 2. Body weight gain was suppressed from initiation of administration in both sexts receiving 50mg/kg/day. 3. There were no significant or remarkable changes in food consumption, hematology and ophthalmology. 4. Urinary findings in animals receiving 50mg/kg/day showed increases of urine and potassium excretion volumes and decrease of urine osmotic pressure in both sexes, negativity of urine protein and decrease of urobilinogen value in females. 5. Biochemical findings in animals receiving 50mg/kg/day showed increase of ured-nitrogen (Urea N) in both sexes and decrease of triglyceride (TG), total cholesterol (T. cho), free cholesterol (F. cho), non-esterified fatty acids (NEFA) and phospholipid (PL) in males. 6. The absolute and/or relative weights of the liver increased in animals receiving 50mg/kg/day. Histopathological examination in animals receiving 50mg/kg/day revealed intranuclear eosinophilic inclusions and cytoplasmic eosinophilic substance in renal proximal tubular epithelium and midzonal lipid droplets in liver. Histochemical examination in animals receiving 50mg/kg/day revealed the slight increase of γ-GTP positive area in peripheral zone of liver. Electron-microscopic examination in animals receiving 50mg/kg/day revealed intranuclear and intracellular large and homogeneous spherical-like structure with low electron density in renal proximal tubular epithelium, and slight hyperplasia of smooth endoplasmic reticulum with dilatation of cisternae and deposition of large lipid droplets in hepatocytes, but there was no difference of VLDL dnd its distributions in hepatocytes among groups. 7. Aftef 5 weeks recovery period, above-mentioned changes were almost disappeared and considered to be reversible. 8. From the above results, the non-effective dose level of P-4 was estimated to be 5mg/kg/day for both sexes.