LOCALIZATION OF NORETHISTERONE IN THE REPRODUCTIVE TRACT OF WOMEN

Abstract

SUMMARY [3H]Norethisterone was administered to women 1, 3 and 24 h before hysterectomy, when samples of blood, adipose tissue and tissues from the reproductive tract were obtained. At 1 h the highest concentrations of radioactivity were found in endometrium and stroma (0·77 and 0·78% respectively of the dose per 100 g tissue), the values in other tissues varying from 0·13 to 0·39%. By 3 h there was a decrease in the concentration in all tissues except adipose tissue and plasma and at this time the range of concentrations in all tissues, apart from plasma (0·40%), were similar (0·08 to 0·19%). There was a further decrease by 24 h. Mean values for the amount of radioactivity present in the tissues at 1 h were: uterus, 0·55%; adipose tissue, 21·6%; blood, 10·1%. By 24 h these values had decreased to 0·1, 7·0 and 6·6% respectively. In adipose tissue most of the radioactivity was present in the freely extractable state at all times studied, whereas in myometrium and cervix the amount of radioactivity freely extractable at 1 h (77%) had decreased by 24 h (39·0%). In plasma the amount of conjugated radioactivity increased from 54% at 1 h to 88% by 24 h. Whereas at 1 h most metabolites in plasma were conjugated as sulphates, by 24 h glucuronide conjugates were also important. In myometrial tissue 17·5 to 47·8% of the radioactivity was associated with the nuclear fraction.