Synthesis of alpha-fetoprotein, albumin and total serum protein in neonatal pigs.

Studies on the incorporation of 3H-leucine established that synthesis of alpha-fetoprotein (AFP) does occur in the neonatal pig. This synthesis probably accounts for the increase in AFP concentration from 0.46 mg/ml on the day after birth to the maximum value of 1.02 mg/ml found 5 days after birth. After the 5th day, the concentration decreases successively and AFP cannot be detected by electroimmunoassay in the sera of 8-week-old pigs. During the first 3 weeks of extrauterine life, the albumin concentration in serum increases from 3 mg/ml to approximately 30 mg/ml due mainly to increased synthesis of albumin. The concentration of AFP in the fetal pig serum decreases from 3 mg/ml at 6.5 cm crown-to-rump (CR) length to 0.8 mg/ml at 28 cm CR length, whereas the albumin concentration increases from 0.2 mg/ml at 6.5 cm CR length to 1.0 mg/ml at 28 cm CR length. The total serum protein content in the fetus is approximately 20 mg/ml irrespective of gestational age. During the first day after birth there is a marked increase in both the synthesis and the concentration of total serum proteins. The concentration rises to 70 mg/ml during the first day and then slowly declines to 65 mg/ml during the 3 weeks following birth.