{'fraction_non_alphanumeric': 0.031061259706643658, 'fraction_numerical': 0.025021570319240724, 'mean_word_length': 4.7711442786069655, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The uptake of progesterone by the uterus of the pregnant rat in vivo and its relationship to cytoplasmic progesterone-binding protein.

The uptake of progesterone-l,2-3H by the uterus of the pregnant rat following sc injection of the radiolabeled hormone was studied. In 11-day rats the 3H-progesterone concentration in the uterus exceeded that in plasma while the concentration in thigh muscle was lower than plasma. In animals killed 4 hour post-injection the uterine/plasma ratio was 2.1 ± 0.1 SE. In 21-day pregnant rats the same dose of 3H-progesterone failed to produce consistently detectable uterine concentrations at 4 hours. Injection of twice the amount of 3H-progesterone provided measurable uterine concentrations but they were consistently lower than those of plasma. The uterine/plasma ratio was 0.57 ±.05 SE. Utilizing sucrose-gradient analysis the progesterone binding activity of the uterine 105,000 g supernatant was examined in vitro. In the cytosol from 11-day pregnant rats a -4S protein component with highaffinity low-capacity progesterone-binding activity was identified. The activity of this component was markedly diminished or a...