ligands such as the beta-adrenergic antagonists ( - ) - [ 3h ] dihydroalprenolol ( dha ) , ( - ) - [ 3h ] propranolol , and ( - ) - [ 125i ] iodocyanopindolol , and the tricyclic antidepressant [ 3h ] imipramine , which are used to assess cell surface receptors for catecholamines and serotonin , appear to be actively transported into cells rather than simply bound to cell surface sites or accumulated by passive diffusion .
C0007634
cells
C0699040
cell surface