Zinc content and distribution in the newborn liver

The newborn liver is a proven model for the study of liver storage of copper and iron. We analyzed zinc concentration and distribution in the livers of newborns and infants using a systematic tissue-sampling technique. We studied 14 newborns of 26-41 weeks of gestation (WG). One stillborn, and three infants (52-90 days old). At autopsy, a longitudinal liver slice extending from the right to the left lobe was subdivided into 10 samples that were analyzed for zinc concentration by atomic absorption spectroscopy. The mean zinc concentration in the newborn liver was 639 micrograms/g of dry tissue (dt). A striking interindividual variability in zinc liver stores was observed; the hepatic concentration of the metal ranged from 300 to 1,400 micrograms/g dt. We found a correlation between zinc liver content and gestational age. In newborns of 27-32 WG, the hepatic zinc concentration was significantly higher (p < 0.01) than in newborns of 34-41 WG. Zinc stores decreased in the postnatal period; in the infant group, the mean liver zinc concentration was 148 micrograms/g dt. The analysis of zinc concentration in 10 blocks from each liver revealed a regular distribution of the metal, without significant differences between liver lobes. Our data show that the newborn liver can be considered an interesting model for the study of zinc storage, which appears to correlate inversely with gestational age. From a practical point of view, the observed regular distribution of zinc implies that, at least in this model, zinc content determined in a small liver sample is representative of zinc content in the whole liver.