The effect of ethanol on uptake of trichloroethylene in isolated perfused rat liver was investigated. The uptake of trichloroethylene was measured in both phenobarbital (PB) non-treated and PB treated rat livers. Furthermore, for PB treated rat livers, the fluorescence of reduced pyridine nucleotides, oxygen consumption, and scanning reflectance spectrum were measured in the liver, perfused with Krebs-Henseleit buffer saturated with a 92%O2-5%CO2-3%CO gas mixture. The uptake of trichloroethylene was decreased by 6.0% in the PB non-treated rat liver and 10.6% in the PB treated rat liver following the addition of ethanol. This uptake decrease was thought to arise mainly from the inhibitory effect of ethanol on mixed-function oxidation in the liver because of the corresponding decrease in oxygen consumption and absorbance difference ΔA<450-490nm>. The inhibition was considered to be due to interference with blectron transfer to the complex of substrate and cytochrome P-450. Increase in intracellular NADH might also affect the formation of trichloroacetic acid since the reduction of NADH in the cytosol attained a maximum with 20 mM ethanol.
The irreversible effect of benzyl alcohol on ATPase, p-nitrophenyl-phosphatase and acetylcholinesterase in the erythrocyte membrane of rats was demonstrated. The ATPase activity in the membranes was stimulated with 10-70 mM benzyl alcohol and inhibited by concentrations greater than 80 mM. p-Nitrophenylphosphatase was gradually inhibited by concentrations of benzyl alcohol greater than 30 mM. The acetylcholinesterase activity was not affected by concentrations below 100mM and strongly inhibited by concentrations of benzyl alcohol greater than 150 mM. With the uptake studies of <14>C-labeled benzyl alcohol by membranes, the highest uptake was obtained in the presence of 200mM of benzyl alcohol. And SDS-polyacrylamide gel electrophoresis showed a binding of benzyl alcohol to the major protein bands of the erythrocyte membrane. Therefore, stimulation of the ATPase activity appeared to be the result of an increase in ion uptake due to an increase in the fluidity of the membrane lipid by benzyl alcohol, and the inhibition of the enzymes may be the result of benzyl alcohol-induced denaturation of the membrane components. The difference in the observed inhibition patterns among ATPase, p-nitrophenylphosphatase and acetylcholinesterase may be related to the sensitivity of benzyl alcohol on those enzymes.
Chloropeptide, a hepatotoxic pentapeptide of Penicillium islandicum Sopp, induces deformation (blebbing or balooning) of the cytoplasmic membrane in the isolated rat hepatocytes, and this hepatotoxic feature is very similar to that of phalloidin.
Oral or intravenous administrasion of allethrin, a synthetic derivative of the pirethrin-based insecticides, produces neurotoxic symptoms consisting of mild salivation, hyperexcitability, tremors and convulsions which result in death. Intracerebroventricular injection of allethrin to mouse at about one-nineth the dose of intravenous administration, produced qualitatively identical but less prominent symptoms, indicating that at least some of the symptoms may be originated in the central nervous system. To investigate the mechanism of action of the compound, we studied the ability of agents which alter neurotransmission to prevent or potentiate the effect of convulsive doses of technical grade (15.5% cis, 84.5% trans) allethrin. Intraperitoneal pretreatment with drugs which block noradrenergic receptors or norepinephrine synthesis, such as pentobarbital, chlorpromazine, phentolamine, phenoxybenzamine and reserpine, depressed the tremor induced by allethrin. The inhibitory effect of reserpine was reversed by phenylephrine. Both the serotonergic blocker, methysergide, and the serotonin depletor, p-chlorphenylalanine, potentiated the effect of allethrin. The potentiating effect of methysergide was antagonized by 5-hydroxytryptamine. However, intracere-broventricular administration of methysergide was ineffective in potentiating the effect of allethrin. α2-and β-adrenoceptor blockers, muscarinic antagonists, GABA mimenergics and morphine had no effect. These results suggest that allethrin produces its neurotoxic responses in mice by acting on the brain and spinal levels. Furthermore, adrenergic excitatory and serotonergic inhibitory mechanisms may be involved in the neural pathway through which the allethrin-inudced tremor is evoked.
Some toxic properties of petasitenine, a hepatocarcinogenic pyrrolizidine alkaloid, were confirmed in 3 parts of studies. Electron microscopic observation of rat liver on the stage of acute toxicity following administration of a toxic dose of petasitenine disclosed the distinctive changes i.e., nucleolar segregation, degradation of endoplasmic reticulum such as formation of concentric whorls in the liver cells. Biochemical test for the mitochondrial function in the isolated mitochondria from rat liver cells revealed on inhibitory effects of petasitenine in the respiratory system, indicating that minor changes of mitochondria on the pyrrolizidine alkaloid may be induced by some other indirect factor. Investigation for the effect of petasitenine on the cell cycle of the cultured cell line from the human carcinoma showed some inhibitory effects in the appearance of cells in S-phase or M-phase, suggesting a possibility that toxicity of petasitenine will be developed in the tissues other than the liver or in the species apart from rodents.
To clarify the role of squalene peroxide in the occurrence of skin damage from sunburn, the optimum condition of squalene peroxidation and the effect of squalene peroxide on cutaneous tissue were examined. Peroxidation of squalene was more easily induced than palmitoleic acid and oleic acid in the unsaturated lipid occurred in sebum. The peroxidation of squalene gradually occurred by U.V. irradiation, and it is parallel to increases in the malonyldialdehyde production (production of lipoperoxide). This peroxidation easily carries out in the Case of high temperature (40°C than 30°C), and in the case of low pH. Good correspondence was recognized among the spectrum of natural daylight, U.V. absorption spectrum of squalene and erythema curve. Squalene and its peroxide have an important role in the occurrence of sunburn, and/or protection from damage caused by U.V. irradiation.
The antispermatogenic effects of 2, 4-dinitro-6-tert-. butylphenyl methanesulfonate (HE-166) were studied in Sprague-Dawley rats. They were fed 25, 100 and 400 ppm of HE-166 in the basal died for one year. Laboratory data showed no significant changes except for increases in γ-globulin, alkaline phosphatase, GOT and GPT values in the 100ppm group. Macroscopically, significant changes were found in the testes in the experimental group, which showed marked atrophy. Histologically, the testes were fined with fibrin exudate in the stroma and there was reduced spermatogonia, celluar debris and giant cells, and even calcification, depending on the dose of HE-166. The anti-fertility effects of HE-166 were also observed by mating rats and checking the pregnancy rate during three generations. These effects might be due to the direct cytotoxic effect of HE-166 on post-meiotic cells as epididymal spermatozoa and testicular sperm and spermatids. As far as tumor incidence was concerned, one case of fibroadenoma of the mammary gland, one case of leiomyosarcoma in the uterus in the 100 ppm group and one case of leiomyoma in the uterus in the 25 ppm group developed at around 8 months, but no other tumors developed.
Urethane has been known for its transplacental carcinogenic effect in mice. Whether or not the treatment of urethane affects embryonic growth and development and induces chromosome aberrations in the embryonic cells in vitro was investigated using the mouse whole embryo culture method. Reports on experiments in vivo showed that lungs and liver were target organs of carcinogenic effects of urethane. In the present experiment, organ (lung and liver)-specific susceptibility to clastogenic effect of urethane was observed in cultured embryonic cells. Further, it is stressed that urethane induced chromosome breaks at concentrations lower than the threshold value for the retardation on embryonic growth and development. Comparing with clastogenic effect of 4NQO on cultured embryonic cells, the clastogenic action of urethane was examined to point out its characteristic feature as a clastogen with special reference to the carcinogenic effects obtained by in vivo experiment.