RECEPTOR-MEDIATED INTERNALIZATION OF NEUROTENSIN IN TRANSFECTED CHINESE-HAMSTER OVARY CELLS

After association with intact Chinese hamster ovary (CHO) cells expres sing the rat neurotensin receptor, tritiated neurotensin was rapidly i nternalized. Internalization was maximal after 30 min and accounted fo r about 90% of the total associated ligand. Neurotensin internalizatio n was not observed at 0-4 degrees and was inhibited by an excess of un labelled neurotensin or by the neurotensin non peptide antagonist, SR 48692. Moreover, the incubation of intact cells for 30 min with 10nM n eurotensin resulted in a significant decrease in the number of the cel l surface neurotensin receptors. These results indicate that the endoc ytosis of membrane bound neurotensin in transfected CHO cells resulted from the internalization of the ligand-receptor complex inside the ce ll, through an agonist-induced process.