Toxicity of diclofenac to isolated hepatocytes.
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Biomedical subjects
Publications and source records attributed to C J Estler.
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The effects of equimolar doses (65.5 mumol/kg intraperitoneally) of three trypanocidal compounds, i.e., pentamidine, 6-amidino-2-(amidinophenyl)indole (DAPI), and 6-imidazolino-2-(imidazolinophenyl)indole (DIPI) on some parameters of liver carbohydrate, lipid and energy metabolism have been assessed in male NMRI mice. Most prominent effects were an initial increase of the blood glucose and fatty acid levels followed by long lasting increases of the hepatic triglyceride and glycogen contents which were accompanied by decreases of the liver pyruvate and lactate and ATP contents. These effects which can be interpreted as results of a transient lipolytic and glycogenolytic effect and a longer lasting inhibition of the energy yielding carbohydrate metabolism were most pronounced after DAPI and DIPI and less marked after pentamidine.
Minocycline (25 to 100 micrograms/g) dose dependently increased serum glutamic oxalacetic transaminase, urea, and bilirubin levels, and the hepatic triglyceride content in mice. In animals pretreated with phenobarbital to enhance minocycline metabolism, the effects on liver triglycerides were attenuated, while the changes in serum glutamic oxalacetic transaminase, urea, and bilirubin were enhanced. It is concluded that part of the toxic effects of minocycline may be produced by a metabolite of minocycline.
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To examine the combined hepatotoxic and nephrotoxic effects of cadmium and ethanol, rats maintained on an ethanol containing liquid diet (5% w/w) were given cadmium either acutely (3 x 1 mg/kg IP) or subacutely (about 14 mg/kg/day PO for 6 weeks). Parameters tested were cadmium, zinc and copper contents of blood and various organs, metallothionein (MT) contents, polysome profile of liver and kidneys, serum SDH and GPT levels and creatinine clearance. Ethanol reduced the hepatic MT contents without altering the polysome profile and the zinc and copper contents. Cadmium on the other hand raised the MT contents in liver and kidneys. This effect of cadmium predominated in the combined treatment. Morphological examination and functional tests (SDH, GPT, creatinine clearance) indicate that cadmium does not enhance the toxic effects of ethanol, and vice versa.
Pentamidine, DAPI and some related compounds (DAI, 6-Br-AI, DPTN, DIPI, 3-Am-DAI, DiaPBF) were investigated in 2 different screening test systems for their potential mutagenic and cytotoxic effects, in the light of their binding to DNA. In the Ames test using Salmonella typhimurium strains TA98 and TA100 with and without metabolic activation no mutagenic effects could be observed. All diamidines tested, except DAI, were toxic at concentrations of 0.5 and 1.0 mumole/plate. In the sister-chromatid exchange (SCE) assay with human peripheral lymphocytes all compounds tested were growth-retarding particularly in the G0 phase. A significant induction of SCEs could only be seen after treatment with the monoamidino compound 6-Br-AI at a concentration of 100 mumole/l. It is concluded from the data obtained that pentamidine and related diamidines in the 2 assays tested show no mutagenic or genotoxic effects, in spite of their tight binding to DNA.
A series of new trypanocidal diamidines was tested for their hepatotoxic potential. At a concentration of 0.5 mmol/l almost all agents tested produced leakage of lactate dehydrogenase and reduced viability of isolated rat hepatocytes. In mice serum sorbitol dehydrogenase was raised by a single i.p. dose of 65.5 mumol/kg. Only two agents, compounds 261/115 and 313/40, were free of these effects at this dose or concentration.
The influence of intrahepatically infused naftidrofuryl (Dusodril) on indocyanine green (ICG) clearance was measured in healthy rats and rats with liver cirrhosis. In control rats naftidrofuryl reduced the ICG clearance from 0.043 to 0.029 mumol/min/g liver. Plasma half-life of ICG was prolonged significantly from 3.07 to 4.25 min. This was probably due to a depression of the cardiovascular function (blood pressure, heart-rate). In cirrhotic rats, the removal rate of ICG (0.050 mumol/min/g liver) was significantly lower and its half-life (7.61 min) longer than in normal rats. Probably the extraction rate for ICG was so low that naftidrofuryl did not further impair the reduced ICG clearance and half-life inspite of reduced diastolic blood pressure and heart rate.
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The influence of the alpha-receptor agonist oxymetazoline, the antihistaminics mepyramine and cimetidine and of cromoglicic acid disodium salt (disodium cromoglycate, DSCG) on the hypotension produced by the trypanocidal diamidines pentamidine, diamidinophenylindole (DAPI) and diimidazolinophenylindole (DIPI) was investigated. 75-100 nmol/kg oxymetazoline were effective only in DAPI-treated animals and diminished the drop of the systolic blood pressure by 25-49%. Pretreatment with DSCG was ineffective in all groups under the conditions used. Preapplication of a combination of 5 mumol/kg mepyramine and 10 mumol/kg cimetidine was effective only in pentamidine-treated animals and reduced the drop of the systolic pressure by 57%.
Tetracycline (100 micrograms/g) and, to a lesser extent, doxycycline (50 and 100 micrograms/g) inhibited the aggregation of free but not of membrane-bound polysomes in the livers of female NMRI mice. In addition tetracycline decreased the RNA content of the fraction of membrane-bound polysomes probably due to detachment from their membrane sites.
The histamine levels in rat plasma treated with various new trypanocidal diamidines and diimidazolines were evaluated by HPLC and fluorometric detection. Equimolar doses (10 mumol/kg) of the new compounds raised the plasma histamine level to a much smaller degree than pentamidine or diminazene.
A series of trypanocidal diamidines and diimidazolines known to cause severe hypotension were tested for their alpha-adrenoceptor blocking properties in vitro. At the postsynaptic alpha 1-receptor of the guinea-pig aorta in vitro all compounds at doses of 0.5 to 50 mumol/l showed weak antagonistic effects against noradrenaline. Similar results were obtained at the presynaptic alpha 2-receptor of the rat vas deferens.
The effect of long-term treatment with fencamfamine on swimming endurance and availability of metabolic substrates was investigated in mice. Fencamfamine (14 micrograms/g per day orally for 6 weeks) reduced maximum swimming capacity by more than 40%. This effect could not be attributed to motor incoordination or a diminution of pre-swimming levels of metabolic substrates such as liver and muscle glycogen or blood glucose and non-esterfied fatty acids. However, during swimming the hepatic and muscular glycogen stores were depleted more rapidly in the fencamfamine-treated animals. Thus it appears that fencamfamine leads more rapidly to a shortage of combustible substrates in the swimming animals.
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