@article {Resink244, author = {T J Resink and T Scott-Burden and C Boulanger and E Weber and F R B{\"u}hler}, title = {Internalization of endothelin by cultured human vascular smooth muscle cells: characterization and physiological significance.}, volume = {38}, number = {2}, pages = {244--252}, year = {1990}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {The binding and internalization of 125I-endothelin (125I-ET-1) was studied in cultured human vascular smooth muscle cells (hVSMC). Discrimination between surface-bound and internalized radiolabeled ligand was achieved using either acetic acid or trypsin treatment of cell layers, with the two procedures yielding comparable results. Total cellular 125I-ET-1 binding hVSMC at 37 degrees was rapid and reached near equilibrium within 30 min. Such binding could be resolved into surface-bound (acid/trypsin-sensitive) and internalized (acid/trypsin-resistant) components. The accumulation of internalized 125I-ET-1 was temperature dependent and occurred at 37 degrees (t1/2 approximately 15 min) but not at 4 degrees. Internalization of 125I-ET-1 by hVSMC was reversibly inhibited by the transglutaminase inhibitor dansylcadaverine (half-maximal inhibitory concentration, approximately 400 microM). Cytosolic acidification of hVSMC (from pH approximately 6.8 to approximately 6.3) by incubation with potassium acetate in a choline buffer also inhibited 125I-ET-1 internalization. Our observation indicate that smooth muscle cells internalize ET-1 via the clathrin-mediated endocytotic pathway. Dansylcadaverine and other inhibitors of transglutaminase inhibited ET-1-stimulated inositol phospholipid hydrolysis in hVSMC and decreased ET-1-induced vasoconstriction in isolated endothelium-denuded blood vessels. Internalization of ET-1 may, therefore, be relevant to the characteristically protracted physiological effects of this peptide on the vasculature.}, issn = {0026-895X}, URL = {https://molpharm.aspetjournals.org/content/38/2/244}, eprint = {https://molpharm.aspetjournals.org/content/38/2/244.full.pdf}, journal = {Molecular Pharmacology} }