RESUMO
The hearts and remaining bodies of embryonic and fetal mice of known gestational age and of neonatal mice up to the age of 8.5 days were freeze-dried, weighed, and analyzed for the amino acid, taurine, by high performance liquid chromatography. Although cardiac taurine is only a small fraction of the taurine in the rest of the body in all animals studied, the concentration of taurine in the heart is similar to that in the rest of the body (40-45 nmole/mg freeze-dried wt) in embryos through Day 14.5 of gestation. Cardiac taurine concentration then begins to exceed that of the remainder of the body which gradually declines throughout the period studied. A doubling of cardiac taurine concentration is seen at birth (Day 19.5) when the cardiac to body taurine ratio rises markedly and is maintained at 2-4 throughout the period of observation. A maximum concentration of cardiac taurine (110 nmole/mg freeze-dried wt) is recorded 2.5 days after birth. The dramatic increase in cardiac taurine concentration at the time of birth follows the reported appearance in neonatal mouse hearts of adult levels of beta-adrenergic receptors and the increased work load of the heart.
