James L. Way

Effects of oxygen on the antagonism of cyanide intoxication: cytochrome oxidase, in vitro.

Since oxygen was reported to be an effective cyanide antagonist in vivo, particularly in the presence of the classic antidotal combination of sodium nitrite and sodium thiosulfate, in vitro studies were initiated in an attempt to investigate the mechanism of oxygen-mediated cyanide antagonism. The effect of oxygen on cyanide-inhibited cytochrome oxidase with and without cyanide antagonist(s) was investigated in a purified membraneous enzyme system prepared from rat liver mitochondria. Cyanide produced a concentration dependent inhibition of cytochrome oxidase, and 100% oxygen did not alter the inhibition produced by KCN either in the presence or absence of sodium thiosulfate. However, the addition of sodium thiosulfate and rhodanese to the assay reactivated the cyanide-inhibited cytochrome oxidase. Kinetic analysis indicated rhodanese competes with cytochrome oxidase for cyanide, and oxygen had no effect on this coupled reaction. In conclusion, the in vivo antidotal properties of oxygen cannot be attributed to oxygen-mediated reactivation of cyanide-inhibited cytochrome oxidase or an oxygen-mediated acceleration of rhodanese detoxification.

Antagonism of cyanide intoxication with sodium pyruvate.

Cyanide intoxication in mice can be effectively antagonized by sodium pyruvate, particularly if it is administered in combination with the antidotes, sodium nitrite and sodium thiosulfate. Potency ratios derived from the LD50 data were compared in groups of mice treated with sodium nitrite, sodium thiosulfate, and sodium pyruvate either alone or in various combinations. These results indicate that the administration of sodium pyruvate alone does provide minimal, but statistically significant, protection against the lethal effects of cyanide. Sodium pyruvate does not enhance the effect of sodium nitrite; however, it does potentiate the antidotal effect of sodium thiosulfate. The sodium thiosulfate and sodium pyruvate combination is not as effective as the sodium nitrite and sodium thiosulfate combination, but the addition of sodium pyruvate to the sodium nitrite-sodium thiosulfate combination further enhances the antidotal effect. No further enhancement is observed when sodium nitrite, sodium thiosulfate, and sodium pyruvate are combined with oxygen.

Resolution of thiosulfate interference in cyanide determination.

Abstract Sodium thiosulfate is commonly employed as an antidote for cyanide intoxication. Unfortunately, thiosulfate decomposes to sulfur dioxide which ultimately interferes with the colorimetric microdiffusion analysis of cyanide. Therefore, it is no longer reliable to determine cyanide blood concentrations after therapy with sodium thiosulfate has been instituted. A procedure has been developed to prevent sodium thiosulfate from interfering with the standard colorimetric method for cyanide determination. Although thiosulfate is still degraded to polythionic acids, this procedure takes advantage of the difference in p K a values of hydrogen cyanide and the various acidic polythionic acids formed upon the acidification of the thiosulfate anion. To ascertain if this modification would circumvent thiosulfate interference under in vivo conditions, mice receiving potassium cyanide were treated subsequently with sodium thiosulfate and the apparent concentration of cyanide in the blood was determined. These studies indicate that the interference of cyanide analysis caused by the presence of thiosulfate anion in biological samples can be resolved.

Cyanide intoxication: Protection with chlorpromazine

Abstract Protection against cyanide intoxication in mice can be enhanced by the administration of chlorpromazine, providing it is given with sodium thiosulfate, or the sodium thiosulfate-sodium nitrite antidotal combination. Protency ratios which were derived from the LD50 values were compared in groups of mice premedicated with chlorpromazine (10 mg/kg) and/or sodium thiosulfate (1 g/kg) and/or sodium nitrite (100 mg/kg). These results indicate that the administration of chlorpromazine alone provides no protection against the lethal effects of cyanide. Chlorpromazine also does not enhance the protective effect of sodium nitrite; however, it strikingly potentiates the effectiveness of sodium thiosulfate either alone or in combination with sodium nitrite.

Cyanide intoxication: Protection with cobaltous chloride

Abstract Protection against the lethal effects of cyanide can be elicited by administration of cobaltous chloride, either alone or in combination with sodium nitrite and/or sodium thiosulfate. Potency ratios derived from the LD50 values were compared in groups of mice premedicated with cobaltous chloride and/or sodium thiosulfate and/or sodium nitrite. Under the conditions of our experiment cobaltous chloride alone is slightly more effective than sodium nitrite; when it is combined with sodium nitrite, an additive effect is obtained. When cobaltous chloride is administered in combination with sodium thiosulfate, a dramatic antagonism of the lethal effects of potassium cyanide is observed. The synergistic antidotal effect of cobaltous chloride may be related to the physiological disposition of the cobaltous ion and its ability to chelate both cyanide and thiocyanate ions.

Effect of sublethal doses of cyanide on glucose catabolism

Abstract The effect of cyanide on the metabolic degradation of glucose in the mouse was investigated by comparing the rate and extent of production of respiratory 14 CO 2 from specifically labeled carbon atoms of glucose, gluconate and glucuronate. Glucose in the untreated animals was metabolized via three pathways: Embde.n-Meyerhof-Parnas pathway and tricarboxylic acid cycle (EMP-TCA), pentose phosphate pathway and glucuronate pathway. Administration of 5 mg/kg of potassium cyanide, a sub-lethal dose, increased catabolism of carbohydrates by the pentose phosphate pathway with a decline in utilization of the EMP-TCA cycle and glucuronate pathway. These results suggest that chronic exposure to cyanide may induce marked alterations in normal carbohydrate metabolism, and the possible relationship to specific pathological conditions is discussed.

Fluorometric determination of cyanide in biological fluids with p-benzoquinone☆

A sensitive, specific fluorometric method has been combined with microdiffusion to measure cyanide in biological fluids. Cyanide reacts with p-benzoquinone to form fluorescent product(s) which are determined in dimethyl sulfoxide. Approximately 0.001 μmol/ml cyanide can be analyzed by this procedure. Sodium thiosulfate interferes with the determination of cyanide by the standard colorimetric procedure, but not with this fluorometric method. Blood cyanide concentrations in mice pretreated with sodium thiosulfate were compared by the fluorometric and colorimetric methods. These results demonstrate that thiosulfate interferes with the detection of cyanide colorimetrically, but not fluorometrically.

Alteration of in vivo glucose metabolism by cobaltous chloride

Abstract The effect of cobaltous chloride on glucose metabolism in intact mice has been investigated by radiorespirometry in animals treated with uniformly labeled [14C]glucose. Mice were pretreated with cobaltous chloride in doses ranging from 5 to 60 mg/kg and 30 min later were given 1 μCi of [U-14C]-glucose containing 100 mg glucose. Respiratory excretion of 14CO2 was decreased by cobaltous chloride, and in lower doses (5–25 mg/kg) this effect was dose-dependent. Additional experiments indicated the decreased respiratory excretion of 14CO2 was not a result of decreased bioavailability of glucose due to enhanced urinary excretion or inhibition of absorption and transport of glucose from the site of administration. These results indicate that cobaltous chloride inhibits glucose oxidation in intact mice as determined by respiratory excretion of 14CO2.

Interference of thiosulfate with potentiometric analysis of cyanide in blood and its elimination.

Abstract Studies with cyanide in combination with various antidotal regimens indicated that sodium thiosulfate interfered with the potentiometric determination of cyanide. The basis for this interference is ascribed to an enhanced biotransformation of thiosulfate in the presence of blood. A microdiffusion technique, coupled with a silver/sulfide ion-specific electrode, caused falsely elevated cyanide levels when samples contained thiosulfate. The contaminant causing the falsely elevated cyanide level is believed to be sulfide anion. This sulfide contaminant can be removed by oxidation with hydrogen peroxide, and the excess hydrogen peroxide subsequently can be eliminated with sodium sulfite. The toxicologic implication of the potentiometric determination of cyanide in the presence of sodium thiosulfate is important because sodium thiosulfate is employed widely as an antidote in cyanide poisoning.

Effect of antagonists on the physiologic disposition of sodium cyanide

Attempts were made to evaluate the effects of pretreatment with air and oxygen either alone or in various combinations with sodium nitrite and/or sodium thiosulfate on the physiological disposition of 14C-labeled sodium cyanide in mice. The radioactive respiratory excretion was studied by radiorespirometry, and the effects of various combinations of cyanide antagonists were compared. Oxygen either alone or in combination with sodium thiosulfate significantly enhanced the respiratory excretion when compared with air. Sodium thiosulfate accelerated the initial rate, but not the total amount of radioactivity excreted. The cumulative recovery of radioactive gases was significantly greater with groups receiving oxygen either alone or with sodium thiosulfate. When sodium nitrite was employed as an antidote either alone or with sodium thiosulfate, no difference in the respiratory excretion was noted between air and oxygen. The use of the sodium nitrite-sodium thiosulfate combination either with air or oxygen resulted in a marked decrease in the initial rate as well as the total amount of respiratory radioactivity excreted. No significant differences between various experimental groups were noted in the total amount of urinary radioactivity excreted or the total body retention of radioactivity.