HYPOXANTHINE, XANTHINE, AND URIC-ACID CONCENTRATIONS IN THE CEREBROSPINAL-FLUID, PLASMA, AND URINE OF HYPOXEMIC PIGS

The concentrations of hypoxanthine, xanthine, and uric acid in plasma and cerebrospinal fluid (CSF), as well as the urinary output of hypoxanthine and xanthine, were measured in four groups of pigs (three groups with different degrees of hypoxemia and one control group). During hypoxemia with arterial O2 tension between 2.1 and 3.0 kPa [group 1, fractional inspired oxygen (FiO2) = 0.08], hypoxanthine increased in CSF from a mean basal value of 18.1 to 39.3 μmol/L at death (p < 0.02), in plasma from 25.4 to 103.6 μmol/L (p < 0.05), and in urine from 21.3 to 87.1 nmol/kg/min (p < 0.02). Xanthine changed in a similar way: in CSF from 4.0 to 10.6 μmol/L (p < 0.02), in plasma from 0.7 to 48.1 μmol/L (p < 0.02), and in urine from 4.0 to 12.6 nmol/kg/min (p < 0.05). Uric acid increased in CSF from 2.7 to 11.6 μmol/L (p < 0.05), and in plasma from 15.4 to 125.0 μmol/L (p < 0.02). During hypoxemia with arterial O2 tension between 3.0 and 4.0 kPa (group 2, FiO2 = 0.11), hypoxanthine increased in the CSF from 14.7 to 42.9 μmol/L (p < 0.02). Plasma hypoxanthine increased from 20.3 to a maximum of 44.1 μmol/L (p < 0.02), but decreased to initial values by the time of death. The urinary excretion of hypoxanthine increased from 13 to 54 nmol/kg/min (p < 0.02). Xanthine increased in the CSF from 3.9 to 13.3 μmol/L (p < 0.02), in plasma from 0.6 to 36.6 μmol/L (p < 0.02), and in urine from 6 to 25 nmol/kg/min (p < 0.02). Uric acid increased in CSF from 3.1 to 16.3 Mmol/L (p < 0.02), and in plasma from 15.3 to 208 μmol/L (p < 0.02). During milder hypoxemia with arterial O2 tension between 4.3 and 5.6 kPa (group 3, FiO2 = 0.14), or in the control group (group 4, FiO2 = 0.21), neither of the metabolites changed significantly. © 1990 International Pediatric Research Foundation, Inc.