Elevation of plasma 7B2 (a novel pituitary protein) in cord blood at obstetrical delivery and the possible correlation with GH

Plasma 7B2-immunoreactivity (7B2-IR) concentrations in umbilical artery (UA), umbilical vein (UV) and maternal vein (MV) were measured by RIA at the time of obstetrical delivery at term. Plasma 7B2-IR concentrations (Mean +/- SEM) in UA (N = 12), UV (N = 16) and MV (N = 16) were 725 +/- 69, 699 +/- 64 and 116 +/- 4.5 pg/ml, respectively. Plasma 7B2-IR concentrations in UA and UV were much higher than those in MV. There was no arterio-venous gradient between UA and UV. A trace amount of 7B2-IR (Mean +/- SEM, 226 +/- 16.8 pg/g tissue) was detected in the placental extracts. A statistically significant positive correlation (r = 0.7595, p less than 0.005) was found between plasma 7B2-IR and GH in the UV. Significant negative correlations between body weight of the neonates and plasma levels of GH (r = -0.6836, p less than 0.01) and 7B2-IR (r = -0.4939, p less than 0.05) were also apparent. When analyzing cord blood plasma using gel permeation chromatography and SDS-polyacrylamide gel electrophoresis, a major peak with an apparent molecular weight of 20,000 was observed. These findings suggest that 7B2-IR in UA and UV originates from the fetus and that 7B2-IR does not permeate through the placenta. The possibility of involvement of 7B2 in fetal growth warrants attention.