Journal ArticleDOI
Changes in the metabolic clearance rate of progesterone in the guinea-pig
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TLDR
The metabolic clearing rate (MCR) of progesterone in guinea pigs was studied using the continuous infusion of tritiated progesterONE and the decrease seems to depend on the presence of a viable conceptus.Abstract:
The metabolic clearing rate (MCR) of progesterone in guinea pigs was studied using the continuous infusion of tritiated progesterone. The clearing rate decreased from 112.8 1 plasma per day per kg to 8.3 1 per day per kg in pregnant animals between Days 15 and 20. This low rate continued for the remainder of gestation. By Day 12 postpartum the MCR returned and reached 85 1 per day per kg. At the time of the decrease in metabolic clearance rate there was an increase in plasma concentration of progesterone. This is possibly related to an increase in binding proteins with a high affinity for progesterone. The decrease in MCR seems to depend on the presence of a viable conceptus.(AUTHORS MODIFIED)read more
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Journal ArticleDOI
Endocrine control of parturition
TL;DR: This chapter aims to bring together some of the abovementioned theories to show that, for example, the role of the fetus in the initiation of parturition and the concept of progesterone withdrawal may be part of the same mechanism.
Book ChapterDOI
Cellular receptors and mechanisms of action of steroid hormones.
TL;DR: Concentrated efforts are being made to discover the molecular mechanism whereby a steroid receptor complex may participate in the regulation of gene expression of the target cells.
Journal ArticleDOI
Progesterone-binding Plasma Protein of Pregnant Guinea Pig: PURIFICATION AND CHARACTERIZATION
TL;DR: PBP could not be induced in nonpregnant animals by administering large doses of estrogen or progesterone, thus raising the possibility that it is synthesized in an organ present only during pregnancy (placenta?). No protein similar to PBP was detected n pregnant rats or women.
Journal ArticleDOI
Myometrium of the Pregnant Guinea Pig: The Probable Importance of Relaxin
TL;DR: Infusions of porcine-relaxin simulated the changes observed in the cross-circulation expenments and the suggestion is made that relaxin or a relaxin-like substance or substances is a major myometrial regulating factor in the guinea pig.
Book ChapterDOI
Progesterone and oestrogen in pregnancy and parturition: comparative aspects and hierarchical control.
TL;DR: The different ways in which the progesterone requirements of pregnancy are met in various species are reviewed here.