Rapid effects of hypoxia on the cerebrospinal fluid levels of adenosine and related metabolites in newborn and one-month-old piglets.

The effect of hypoxia on the levels of adenosine, inosine and hypoxanthine in the cerebrospinal fluid (CSF) was determined by HPLC in newborn (1- to 3-day-old, n = 6) and 1-month-old (n = 5) piglets. Serial CSF samples (q 60 s) were obtained from the cisterna magna during normoxia and a 5-min hypoxia test (PaO2 = 26.5 +/- 2.9 Torr). In normoxia, newborns had a lower mean (+/- SEM) CSF concentration of adenosine (0.72 +/- 0.17 vs 2.60 +/- 0.44 microM) and a higher concentration of hypoxanthine (4.88 +/- 0.41 vs. 1.39 +/- 0.60 microM) than the mature piglets (p less than 0.05). In all animals, hypoxia induced an increase in CSF levels of adenosine and its metabolites between 2 and 4 min. However, peak adenosine concentrations were higher in mature (4.17 +/- 1.41 microM) than in newborn (1.55 +/- 0.29 microM) piglets (p less than 0.05). These data might explain deficient vasodilator adaptation required for neonatal CBF regulation.