부산대학교 도서관

The aminopyrine (AP) breath test (BT) has been used in adults as a measure of hepatic N-demethylase activity. In order to study maturational changes in enzyme function, 13C AP (2 mg/kg) was administered orally to infants (n=13) between the ages of 1 and 38 wk. Breath samples for measurement of 13CO2enrichment were collected for six hours after administration. Nine of 10 term infants < 6 wk of age showed no detectable oxidation (peak 13CO2output < 0.05% dose/min). Three of 3 infants over 14 wk of age showed oxidation (0.221, 0.196, and 0.261% dose/min at 15, 18, and 38 wk, respectively). Absorption was excluded as a limiting variable since no improvement in oxidation rates was found when the AP was administered again as an IV bolus in 9 of the original 10 infants < 6 wk. Elimination of labeled 13CO2as a limiting variable was excluded since the 9 infants displayed normal bicarbonate kinetics measured by a 6-h 13C bicarbonate BT using an IV dose of 50 μmol/kg. Conclusions: 1) Maturational differences are seen in the metabolism of AP; 2) These differences may reflect immaturity of N-demethylase activity or diversion of the liberated formaldehyde into biosynthetic rather than oxidative pathways.