Changes in oxypurine concentrations in vitreous humor of pigs during hypoxemia and Post-Mortem

Abstract

In the vitreous humor from three hypoxemic and one control group of pigs, hypoxanthine, xanthine, and uric acid concentrations were measured. The purine concentrations were measured before the hypoxemia, at the time of death, and 24 h post-mortem. During hypoxemia with arterial O2 tension between 2.1 and 3.0 kPa [fractional inspired oxygen (FiO2) = 0.08], hypoxanthine concentrations increased from a mean basal value of 11.7 ± 5.6 μmol/L to 16.3 ± 2.4 nmol/L at the time of death (NS). Xanthine concentrations changed from a basal value of 0.3 ± 0.1 μmol/L to 0.6 ± 0.2 μmol/L (p < 0.02), and uric acid changed from 3.4 ±1.1 μmol/L to 5.0 ± 4.5 μmol/L (NS). During hypoxemia with arterial O2 tension between 3.0 and 4.0 kPa (Fi02 = 0.11), hypoxanthine increased in the vitreous humor from a mean basal value of 9.1 μmol/L to 20.3 μmol/L at the time of death (p < 0.02). Xanthine concentrations increased from 0.3 μmol/L to 1.3 μmol/L (p < 0.05), whereas there was no change in uric acid concentration (basal 5.0 ± 0.8 nmo/h and final 4.5 ±1.0 μmol/L). During milder hypoxemia with arterial O2 tension between 4.3 and 5.6 kPa (FiO2 = 0.14), or in the control group (FiO2 = 0.21), neither of the metabolites changed significantly. The vitreous humor was not stable postmortem, inasmuch as the mean concentration of hypoxanthine increased from 18.2 ± 7.7 nmol/L to 121.6 ± 57.4 μmol/L 24 h post-mortem (p < 0.01). In the same period, xanthine increased from a mean 0.9 ± 0.6 μnol/L to a mean 4.9 ± 5.2 μmol/L (p < 0.01). © 1990 International Pediatric Research Foundation, Inc.