Time‐ and Temperature‐Dependent Changes in Cytochrome c Oxidase Activity and Cyanide Concentration in Excised Mice Organs and Mice Cadavers

Abstract

Postmortem stability of cyanide biomarkers is often disputed. We assessed the time and temperature-dependent changes in cytochrome c oxidase (CCO) activity and cyanide concentration in various organs of mice succumbing to cyanide. Immediately after death, excised mice organs and mice cadavers were stored at room temperature (35°C ± 5°C) or in frozen storage (-20°C ± 2°C). At various times after death, CCO activity and cyanide concentrations were measured in excised mice organs or organs removed from mice cadavers. The study revealed that (i) measuring both the biomarkers in mice cadavers was more reliable compared to excised mice organs, (ii) measuring temporal CCO activity and cyanide concentration in vital organs from mice cadavers (room temperature) was reliable up to 24 h, and (iii) CCO activity in the brain and lungs and cyanide concentration in organs from mice cadavers (frozen) were measurable beyond 21 days. This study will be helpful in postmortem determination of cyanide poisoning.

The two faces of cyanide: an environmental toxin and a potential novel mammalian gasotransmitter

“…Since oxidative phosphorylation is essential for ATP generation in mammalian cells, a cyanide‐mediated shutdown of Complex IV activity, and a consequent inhibition of mitochondrial electron transport and aerobic ATP generation would be expected to severely affect the function of all cells, especially those with high bioenergetic demand (e.g., developing/proliferating cells, neurons, cardiac myocytes). Indeed, in vivo or ex vivo studies show that ATP and high‐energy phosphate content of the tissues decrease rapidly and precipitously after systemic exposure to cyanide [ 43 , 44 , 45 , 46 , 47 , 48 , 49 ] and the inhibition of mitochondrial Complex IV is well detectable in various tissues ex vivo [ 22 , 48 , 50 , 51 , 52 ]. In line with the inhibition of mitochondrial function, tissues exposed to cyanide lose their ability to extract oxygen, even in the presence of adequate blood flow [ 53 , 54 ], a phenomenon called ‘cytotoxic hypoxia’.…”

Efficacy assessment of co-treated alpha-ketoglutarate and N-acetyl cysteine against the subchronic toxicity of cyanide in rats

“…In the outer well, 0.5 mL of blood and 1 mL 30% sulfuric acid (H 2 SO 4 ) was added, while to the central well, 0.75 mL 0.1 N sodium hydroxide (NaOH) was added. The Conway cells were immediately covered with glass plates and sealed with petroleum jelly and placed on a rotary plate shaker (TITRAMAX 100; Heidolf, Schwabach, Germany) at 450 r/min for 4 h. Soon after, 0.75 mL aliquot of NaOH was drawn from the central well for cyanide estimation using pyridine-pyrazolone reagent (Singh et al, 2015). Briefly, to an aliquot of NaOH, 150 mL of chloramin T-phosphate reagent (0.25 chloramin T and 1 M monosodium phosphate in 1:3) was added and incubated in an ice bath for 2 min.…”

“…Measurement of cyanide concentration in tissue homogenates was measured by the microdiffusion method using Conway cells (Singh et al, 2015). In the outer well, 0.5 mL of blood and 1 mL 30% sulfuric acid (H 2 SO 4 ) was added, while to the central well, 0.75 mL 0.1 N sodium hydroxide (NaOH) was added.…”