Metabolism of [3H]noradrenaline by the isolated rat uterus

The metabolism of [3H]noradrenaline by uterine horns from estrous, ovariectomized, and ovariectomized and estrogen-treated rats was explored. Uterine strips are able to take up [3H]noradrenaline and store it for up to 85 min after the isotope incubation. The major compounds retained in the tissue from rats either ovariectomized or during estrus were [3H]noradrenaline and 3H-labelled O-methylated deaminate metabolites. The [3H]3,4-dihydroxyphenylglycol ([3H]DOPEG) and 3,4-dihydroxymandelic acid ([3H]DOMA) fractions were higher in tissues from ovariectomized rats than during estrus. Ovariectomy also increased significantly the spontaneous efflux of [3H]DOPEG and [3H]DOMA. The metabolic pattern of [3H]noradrenaline both in the tissue and in the efflux from ovariectomized rats was changed by estrogen treatment and became similar to those obtained during estrus. These data suggest a possible modulation of the noradrenaline metabolism by estrogens on the isolated rat uterus.