Transplacental effects of allopurinol on suppression of oxygen free radical production in chronically instrumented fetal lamb brains during intermittent umbilical cord occlusion.

OBJECTIVE: To evaluate the transplacental effect of allopurinol, which acts as a xanthine oxidase inhibitor and free radical scavenger, on inhibiting the production of superoxides during intermittent partial umbilical cord occlusion.
METHODS: Using four chronically instrumented fetal lambs, ewes received 400 mg allopurinol over a period of two hours. Concentrations of allopurinol and oxypurinol in blood samples from mothers and fetuses and fetal brain microdialysis perfusate were measured by HPLC. In another three cases the production of superoxide during intermittent umbilical cord occlusion was studied by measurement of chemiluminescence in perfusate before and after administration of Allopurinol.
RESULTS: (i) Allopurinol concentration in mothers had reached equilibrium by 30 min after starting administration and maintained a concentration about 6 mug/ml. Allopurinol concentration in fetuses increased gradually and reached 2.25 +/- 0.54 microg/ml at 120 min; (ii) Oxypurinol concentration in both mothers and fetuses increased during administration of allopurinol; (iii) Concentrations of allopurinol and oxypurinol in the perfusates reached 0.32 +/- 0.12 microg/ml, 0.53 +/- 0.22 microg/ml at 120 min respectively; and (iv) Administration of allopurinol significantly suppressed superoxide production during intermittent partial umbilical cord occlusion.
CONCLUSION: These results demonstrated a good transfer of allopurinol from mother to fetus and suggested the possibility of intrauterine treatment to inhibit fetal brain damage resulting from increased oxygen free radicals.