Developmental changes in concentrations of iron, copper, and zinc in mouse tissues.

Developmental changes in tissue concentrations of iron, copper, and zinc were determined from birth to day 60 in the hybrid mouse. Liver, iron, and copper concentrations decreased by 80% during the first 2 weeks of life. After 4 weeks more, liver iron concentrtion increased to levels similar to those found at birth, while copper concentrations remained low. Liver zinc concentrations did not change during the experimental period. Brain iron, copper, and zinc concentrations increased during the postnatal period. The increases in iron and zinc concentrations were gradual, with 35% overall increases. Copper concentration increased by 350%, primarily between day 7 and day 22. Kidney iron concentration was constant until day 26, but between day 26 and 60 it increased by 100%. Kidney copper concentration increased from birth to day 28 by about 40%, and then remained constant. Kidney zinc concentratin did not change with age. Spleen iron concentration did not change until day 40, then increased by about 200% to day 50. Spleen copper and spleen zinc concentrations did not change with age. These observations identify several time periods in which concentrations of iron, copper, and zinc are changing rapidly in tissues of the young mouse. The identification of these patterns allows the investigator to choose optimum time periods for the study of mineral metabolism during the postnatal period.