hCS regulation during pregnancy.

In order to define the homeostatic mechanisms which affect the secretion of human chorionic somatomammotropin (hCS), we have determinated its plasma levels by a radioimmunoassay method in normal, prediabetic, and chemically diabetic pregnant women in basal conditions and after stimuli. Oral glucose failed to modify hCS plasma levels as also did continuous intravenous glucose infusion. Rapid acute intravenous glucose decreased them, suggesting that only sudden changes in maternal plasma glucose can exert a regulatory effect on hCS secretion. In travenous arginine increased hCS levels, new evidence of the great similarity of structure and function between growth hormone and hCS.