Biomaterial Database

Excretion of urea by the foetal guinea pig. 1978

J Horn

1. The placental transfer of urea was studied by perfusing the guinea-pig foetal placenta in situ with dextran solutions containing various amounts of urea, and radioactively labelled urea. 2. Transfer of urea was linearly related to the difference in concentration between the maternal and the foetal sides of the placenta, but transfer in both directions across the placenta was equal when the concentration of urea in the perfusing fluid was 2.5--3.5 mmol/l less than the maternal arterial value. This suggested that urea may be transferred against a concentration gradient. 3. Foetal plasma urea concentrations were found to be 0.5 mmol/l less than the maternal, suggesting that active transfer from the foetal circulation to the maternal can occur. However, because of the close relationship between foetal and maternal plasma urea (r = 0.96), it is concluded that the major control of foetal urea concentrations is by diffusion of urea between maternal and foetal extracellular fluids.

UI	MeSH Term	Description	Entries
D008431	Maternal-Fetal Exchange	Exchange of substances between the maternal blood and the fetal blood at the PLACENTA via PLACENTAL CIRCULATION. The placental barrier excludes microbial or viral transmission.	Transplacental Exposure,Exchange, Maternal-Fetal,Exposure, Transplacental,Maternal Fetal Exchange
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D005260	Female		Females
D005333	Fetus	The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.	Fetal Structures,Fetal Tissue,Fetuses,Mummified Fetus,Retained Fetus,Fetal Structure,Fetal Tissues,Fetus, Mummified,Fetus, Retained,Structure, Fetal,Structures, Fetal,Tissue, Fetal,Tissues, Fetal
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill
D014508	Urea	A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.	Basodexan,Carbamide,Carmol