Preferential uptake of 14c-alpha-aminoisobuturic acid into mouse uterine tissue during early pregnancy.

The uptake of 14C-AIB into uterine tissue and some other organs was studied during early implantation. Mice in experimentally delayed implantation were given estrogen and 14C-AIB at different time intervals. Mice in delayed implantation given only 14C-AIB displayed a low transport rate into the uterine tissue, comparable with that for the diaphragm muscle. However, if the estrogen injection preceeded that of the 14C-AIB by 4 to 8 h the transport capacity increased by a factor of at least 4 times while the uptake for the diaphargm muscle remained low. Under such conditions 14C-AIB-accumulation into uterine tissue was favoured for at least 4 h of in vivo incubation with the labeled amino acid.