In order to evaluate the mechanism of high growth hormone (GH) secretion in perinatal life, the levels of GH and growth-hormone-releasing factor (GRF) in cord blood were determined. Plasma-immunoreactive GRF was measured by a double antibody RIA method. The levels (mean ± SD) of GH, GRF and somatostatin (SRIF) were 23.4 ± 10.2 ng/ml, 49.5 ± 11.7 and 41.5 ± 10.4 pg/ml, respectively; they were remarkably higher than those of healthy adults. In Statistical analysis, there were no significant relationships among the levels of GH, GRF or SRIF. We speculate that a high GRF release from the hypothalamus might increase the secretion of GH in the perinatal period.

In this paper, the effect of acute human growth hormone (GH) administration on erythrocyte insulin binding in GH deficient children (N = 6) was studied. Following GH (0.25 U/kg) administration, the blood levels of GH peaked within 4 to 8 h and returned to basal levels 24 h later. However, the changes in somatomedin activity, free fatty acid (FFA), urea, blood glucose and 125I-insulin binding to erythrocyte were observed around 24 h following the injection, and there was a converse relationship between maximum percent 125I-insulin binding (IBmax) and FFA (P less than 0.02). By Scatchard analysis it was found that the decrease in IBmax is mainly due to the change in the number of insulin receptors. These results suggest that GH may possibly affect the insulin binding to erythrocyte indirectly through metabolic changes as a result of hormonal changes in GH deficient children.