Radioiodinated CGP 42112A: a novel high affinity and highly selective ligand for the characterization of angiotensin AT2 receptors.
CGP 42112A, a potent angiotensin AT2 receptor selective ligand, was radio-iodinated and its binding characteristics compared with those of [125I]angiotensin II. In human myometrium (only AT2 expressed), binding was saturable (Kd 1.03 x 10(-10) M; Bmax 807 fmol/mg) and reversible (K+1 1.89 x 10(8) M-1.min-1; K-1 3.77 x 10(-3) min-1). The order of potency of a number of peptides and non-peptides was the same as when [125I] angiotensin II was used as tracer. No specific binding could be detected on membranes from vascular smooth muscle cells (only AT1 expressed). In rat adrenal glomerulosa membranes (mixed AT1/AT2), [125I]CGP 42112A bound only to AT2. [125I]CGP 42112A can therefore be used as a specific probe for AT2 receptors and will be especially useful in tissues where other subtypes are also present.
Whitebread
S E
SE
Ciba-Geigy Ltd, Research Department, Basle, Switzerland.
Taylor
V
V
Bottari
S P
SP
Kamber
B
B
de Gasparo
M
M
D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D057911:Angiotensin Receptor Antagonists; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D015394:Molecular Structure; D009215:Myometrium / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism*; D011869:Radioligand Assay; D011945:Receptors, Angiotensin / Q000378:metabolism*
D057911:Angiotensin Receptor Antagonists; D007457:Iodine Radioisotopes; D009842:Oligopeptides; D011945:Receptors, Angiotensin; D000804:Angiotensin II; C060894:CGP 42112A