Binding of radioactivity from (14C)thiourea to rat lung protein.
Binding of radioactivity from [14C]thiourea (TU) to rat lung protein was found to occur in vitro. Two binding sites are present. One possesses low affinity/high capacity while the other is characterized by high affinity/low capacity. In vitro binding of [14C]TU to lung protein can be antagonized by the presence of either unlabeled congeners (alpha-napthylthiourea or phenylthiourea) or thiol-containing compounds (cysteine, reduced glutathione). Conversely, depletion of lung-reduced glutathione by means of diethyl maleate administration results in elevated protein binding. Prior administration (24 hr) of a sublethal dose of TU (which renders tolerance to a subsequent lethal dose in vivo) results in a decrease in in vitro binding of radioactivity from [14C)TU to lung protein. In addition, immature rats, which are less sensitive to the edematogenic effect of TU, bind less radioactivity from [14C]TU to lung protein when the drug is administered in vivo. These results suggest a correlation between [14C]TU binding to lung protein and the pathophysiological effect of the drug in the lung.
D000375:Aging; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D003545:Cysteine / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D007700:Kinetics; D008168:Lung / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D010670:Phenylthiourea / Q000494:pharmacology; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D013890:Thiourea / Q000031:analogs & derivatives / Q000378:metabolism*
D011506:Proteins; D010670:Phenylthiourea; D005978:Glutathione; D013890:Thiourea; D003545:Cysteine