| Abstrakt: |
Under in vitroconditions, the human endometrium and myometrium metabolized norgestrel to 13β-ethyl,17α-ethynyl-5β-oestrane,3α,17β-diol; 13β-ethyl,17α-ethynyl-5β-oestrane,3β,17β-diol and to some unidentified polar compounds, which suggests that the enzyme 3-ketosteroid reductase is present in these tissues. There was no qualitative difference in the conversion of norgestrel to its metabolites by the endometrium and myometrium, though some quantitative differences were observed i.e. more norgestrel was metabolized by the proliferative as compared with the secretory endometrium and myometrium. Furthermore, the conversion of norgestrel to its metabolites was higher in the endometrium as compared with the myometrium. Among the subcellular fractions of the endometrium and myometrium, the cytosol fraction showed the highest conversion of norgestrel. The main metabolite formed in the endometrium, myometrium and in their subcellular fractions was 3α-hydroxy-5βH-tetrahydronorgestrel. The implications of the formation of metabolites of norgestrel with very low biological activity as a factor involved in the regulation of the action of norgestrel in the endometrium are discussed. |
