Aa. Hancock et al., [H-3] A-81988, A POTENT, SELECTIVE, COMPETITIVE ANTAGONIST RADIOLIGAND FOR ANGIOTENSIN AT(1) RECEPTORS, European journal of pharmacology. Molecular pharmacology section, 267(1), 1994, pp. 49-54
Abbott-81988 (A-81988), l]biphenyl-4-yl)methyllamino}pyridine-3-carbox
ylic acid is a potent, competitive, non-peptidic antagonist of angiote
nsin AT1 receptors. A-81988 was labeled with tritium to high specific
activity (16 Ci/mmol) and radioligand binding assays performed in rat
liver membranes. [H-3]A-81988 bound with high affinity (K(D) = 0.57 nM
) and the K(D) determined from kinetics assays was similar. Non-specif
ic binding (defined with 10(-6) M angiotensin-II) was very low (< 6% a
t the K(D)). The binding of [H-3]A-81988 was competitive and exhibited
appropriate pharmacological specificity for compounds acting at angio
tensin AT1 receptors. These properties demonstrate that [H-3]A-81988 w
ill be a useful radioligand for studies of angiotensin AT1 receptors i
n various tissues.