The role of methemoglobin in acute butyl nitrite toxicity in mice

When mice were exposed to butyl nitrites in an inhalation chamber, a significant level of methemoglobinemia is produced. The potency order for methemoglobin production of the four butyl nitrites (n-, iso-, sec-, tert-) is the same as that of their lethal concentrations (LC50 values) and parallels the ability of the agents to cause methemoglobin formation in mouse erythrocytes in vitro. Pretreatment with a single dose of methylene blue prevents the methemoglobin formation and protects against the lethality of the butyl nitrites.

Red cell glutathione deficiency: clinical and biochemical investigations using sheep as an experimental model system

The biochemical properties of red cells from normal sheep and sheep with three types of red cell glutathione (GSH)-deficiency were compared. One deficiency was due to an impaired transport system for amino acids (lesion 1), one was the result of a diminished activity of gamma-glutamyl cysteine synthetase (GC-S) (lesion 2) and the third was a combined deficiency produced by selective breeding to give animals with both lesions 1 and 2. Under normal husbandry conditions no clinical symptoms were apparent in sheep with lesion 2, but red cells from sheep with lesion 1 and lesions 1 + 2 showed an increased osmotic fragility, a greater tendency to form Heinz bodies and a shorter potential life span than normal. These deficiencies were not found in tissues other than blood. Normal and GSH-deficient red cells had the expected low concentrations of 5-oxoproline. The effects of the toxic agents phenylhydrazine, s-methylcysteine sulphoxide and nitrite in vivo were measured in sheep of the different types. GSH-deficient sheep responded earlier and more dramatically than normal sheep, showing greater methaemoglobin formation, and for phenylhydrazine and s-methylcysteine sulphoxide, more severe anaemia. Sheep with the combined lesions were in general the most susceptible, but even they had the ability to recover from moderately severe oxidative challenge.

Formation of nitroso compounds and mutagens from tranquilizers by drug/nitrite interaction

The formation of nitroso compounds and mutagens by drug/nitrite interaction was screened for 14 tranquilizers. The drug (0.05 M) was reacted with nitrite (0.5 M) at pH 3-3.5. After 4 h at 37 degrees C, nitroso compound formation was observed for flupentixol, chlordiazepoxide, spiperone, thiothixene, and chlorprothixene in more than 40% yield. Mutagenicity was found in the reaction products of opipramol, chlordiazepoxide, bromazepam, thiothixene, and carpipramine by the Ames assay using Salmonella typhimurium TA98 and TA100 as tester strains.

Acute oral toxicity of butyl nitrite

Butyl nitrite is present in consumer products subject to abuse by inhalation. When inhaled, intense peripheral vasodilation and tachycardia ensue, described by users as a 'rush'. When ingested, toxic sequelae include methemoglobinemia and hypokinetic anoxia. The median lethal oral dose to rats of this compound is, with 95% confidence, 83 +/- 3.5 mg kg-1.

Induction of liver tumors in Wistar rats by sodium nitrite given in pellet diet

Sodium nitrate was given to male noninbred Wistar rats at levels of 800 ppm and 1,600 ppm in a pellet diet for 646 experimental days. The first tum or was found on day 441 in the liver of a rat given a diet containing 800 ppm sodium nitrite. On day 646, liver tumors were found in 1 of 22 rats (4.5%) on an 800-ppm sodium nitrite diet and in 5 of 19 rats (26.3%) on a 1,600-ppm sodium nitrite diet. The incidence of liver tumors in the rats fed 1,600 ppm sodium nitrite was significantly different from that in controls as judged by the t-test (P < 0.05). A hepatocellular carcinoma and a hemangioendothelial sarcoma of the liver were found on day 646 in 2 rats fed 1,600 ppm sodium nitrite. One mammary tumor but no liver tumors were found in the 19 control rats. The concentration of sodium nitrite decreased after preparation of the pellet diet, but it was still at least 70% of the initial amount when the pellets were given to the rats. Volatile N-nitroso compounds, especially dimehylnitrosamine, at ppm levels were detected in the pellet diet with a gas chromatography-thermal energy analyzer.

Gas chromatographic determination of nitrite in foods as trimethylsilyl derivative of 1H-benzotriazole

1,2-Diaminobenzene reacts with nitrite in acidic solution to form 1H-benzotriazole, which can be extracted into ethyl acetate. After evaporation of the ethyl acetate, 1H-benzotriazole is determined as its trimethylsilyl derivative by gas--liquid chromatography on a column of 15% SE-30 on chromosorb G HP at 200 degrees C with flame-ionization detection. The nitrite concentration is calculated from the peak height. Amounts of 0.5--10 microgram of nitrite-nitrogen can be determined. For the determintion of nitrite in foods, clean-up of the crude extracts by ion-exchange column chromatography allows the satisfactory elimination of interferents and permits concentrations down to 0.41 ppm to be determined. The recovery of the nitrite added to foods at the 4.1 ppm level ranges from 94.6 to 98.7% and at the 8.2 ppm level it ranges from 95.2 to 98.8%. The trimethylsilyl derivative of 1H-benzotriazole was identified as 1-trimethylsilylbenzotriazole by combined gas chromatographic--mass spectrometric examination and nuclear magnetic resonance spectrometry.

Induction of 8-azaguanine-resistant mutation and neoplastic transformation of hamster embryonic cells by coadministration of sodium nitrite and aminopyrine

Hamster embryos in utero on the 11th or 12th day of gestation were treated simultaneously with aminopyrine (Ap) and sodium nitrite (NaNO2) by oral administration of the compounds to the mothers by stomach tube. For measurement of induction of 8 AG-resistant mutations, the embryonic cells from treated and control mothers were cultured in MEM plus 10% FBS for 72 h and then selected in medium containing 10 or 20 microgram/ml of 8 AG. The number of 8 AG-resistant colonies was markedly increased after co-administration of Ap and NaNO2, and slight induction of mutations was also observed in cells from mothers given NaNO2 alone. This treatment also caused morphological or malignant transformation of cultured cells. About 5- to 6-fold increase in the number of transformed colonies was observed in cells from mothers given Ap plus NaNO2. Cells from the transformed colonies produced tumors when implanted into the cheek pouches of young golden hamsters. These tumors were diagnosed as pleomorphic fibrosarcomas. Similar results were obtained with cells from embryos treated transplacentally with NDMA as positive controls. A single transplacental oral application of Ap at 200 mg/kg or of NaNO2 had only slight biological actions to the cultured embryonic cells. NDMA was produced in the stomach of animals treated simultaneously with Ap and NaNO2. A small amount of NDMA was also detected in the stomach after a single dose of NaNO2.

Induction of cancer of the glandular stomach in rats by an extract of nitrite-treated fish

Treatment of a homogenate of the mackerel fish Sanma hirakl with nitrite at pH 3 led to the development of direct-acting mutagenic activity for Salmonella typhlmurium TA-1535. Repeated gastric intubation three times/week for 6 months of an extract containing this mutagenic activity into noninbred Wistar rats led to the induction of tumors in 8 of 12 rats 12-18 months later. Adenomas and adenocarcinomas were found in the glandular stomach, squamous cell carcinoma was observed in the forestomach, and adenocarcinoma was found in the small intestine and pancreas. Furthermore, precancerous lesions (including intestinal metaplasia and glandular hyperplasia of the glandular stomach as well as squamous cell hyperplasia) were noted in virtually all of the animals at risk. No tumors were seen in 8 control rats given the untreated fish extract alone; 1 rat had glandular hyperplasia and intestinal metaplasia. Thus a mutagenic extract of nitrite-treated fish was demonstrated to induce, in the rat glandular stomach, cancers identical to gastric cancer observed in man. Preventive m:asures, including reduction of the intake of pickled foods and the year-round daily availability of foods containing vitamin C, are discussed.