Avian vitreous humor concentrations of inosine, hypoxanthine, xanthine, uric acid, uracil and uridine as influenced by age and sex: their relevance as indicators of ante-mortem hypoxia.

An investigation was made to determine the effects of age and sex on postmortem concentrations (mumol/l) of inosine, hypoxanthine, xanthine, uric acid, uracil and uridine in the vitreous humor of chickens (Gallus domesticus). Five male and 5 female chickens were sampled each week from 0-10 weeks of age. Samples were collected at 0 and 24 h postmortem and analysed by HPLC. Hypoxanthine, uric acid and uridine were detected at both 0 and 24 h postmortem whereas inosine, xanthine and uracil were detected only at 24 h postmortem. Neither sex nor the sex X age interaction influenced the concentrations of the compounds investigated (P greater than 0.01). Age had a significant influence on the concentrations of all compounds at 24 h postmortem (P less than 0.0001). At 0 h postmortem, age significantly affected the levels of hypoxanthine and uridine (P less than 0.0001) but not uric acid (P = 0.014). All compounds occurred at higher concentrations at 24 than 0 h postmortem with the exception of uridine at 0 and 1 week of age. Previous studies using data confounded by age and postmortem sampling time have concluded that postmortem vitreous humor hypoxanthine concentration is a useful indicator of antemortem hypoxia. The results of this study cast doubt on that conclusion. Age and postmortem sampling time should be rigorously controlled when conducting quantitative analyses of these compounds in vitreous humor.

Postmortem time and storage temperature affect the concentrations of hypoxanthine, other purines, pyrimidines, and nucleosides in avian and porcine vitreous humor.

An HPLC method was used to determine whether postmortem time and storage temperature affect the concentrations of purines, pyrimidines, and nucleosides in avian and porcine vitreous humor. Inosine, hypoxanthine, xanthine, uric acid, uracil, uridine, and thymine were identified in the vitreous humor of chickens (Gallus domesticus). Time from death to sample collection (0-192 h) influenced the concentrations of all seven compounds (p less than 0.01 to less than 0.0001). The storage temperature of chicken carcasses before sampling (6 or 20 degrees C) had a significant influence on the concentrations of inosine, hypoxanthine, xanthine, uric acid, uracil, and thymine (p less than 0.05 to less than 0.0001). The interaction of postmortem time with temperature was significant for all seven compounds (p less than 0.01), with the rate of increase in concentration over time being higher at 20 than 6 degrees C. At 0 h postmortem, the vitreous humor of pigs (Sus scrofa) contained detectable levels of hypoxanthine, uracil, and uridine. Inosine, hypoxanthine, xanthine, guanosine, guanine, uracil, and uridine were detected after storage of pig eyes for 24 h at 20 degrees C. Between 0 and 24 h postmortem, there was a 22-fold increase in hypoxanthine concentration and a 13-fold increase in uracil concentration (p less than 0.0001). It was concluded that postmortem time and temperature are factors that must be taken into consideration when making comparisons of purines, pyrimidines, and nucleosides between groups and in relating postmortem vitreous humor hypoxanthine concentrations to antemortem hypoxia.