STUDIES ON THE BIOLOGIC CHARACTERIZATION OF HUMAN GONADOTROPINS II. COMPARISON OF HUMAN PITUITARY GONADOTROPIN (URINE) AND HUMANCHORIONIC GONADOTROPIN (URINE)*

Abstract

Six assays were carried out for human chorionic gonadotropin (HCG) by the method of simultaneous response of the ovary and uterus of the intact immature rat. The constants of these assays were then compared with similar constants derived from assays of human pituitary gonadotropin (HPG) reported earlier. The slope of the ovarian response to HPG was five times that of HCG. The uterine response to HPG was a linear function of log dose; that to HCG was autocatalytic and could be separated into 2 components, each of which was a linear function of log dose. The slope of the uterine response to HPG was not the same as that of either of the 2 limbs of the response to HCG. The dose ratios that integrate gonadotropic action on the ovary and uterus were widely different for HPG and HCG. It was evident that HCG was six times more effective than HPG in inducing the secretion of estrogen by the ovary. It was concluded that HCG and HPG are vastly different in their gonadotropic action, and that the constants of the assay by this biologic system can be used for the characterization and identification of these 2 human gonadotropins.