MRS-1191 is a potent and selective A3 adenosine receptor antagonist with a KB value of 92 nM, a Ki value of 31.4 nM for human A3 receptor and an IC50 of 120 nM for CHO cells[1].
The effects of putative A3 adenosine receptor antagonist of MRS-1191 is characterized in receptor binding and functional assays. MRS-1191 is found to be competitive in saturation binding studies using the agonist radioligand [125I]AB-MECA (N6-(4-amino-3-iodobenzyl)adenosine-5'-N-methyluronamide) at cloned human brain A3 receptor expressed in HEK-293 cells. Antagonism is demonstrated in functional assays consisting of agonist-induced inhibition of adenylate cyclase and the stimulation of binding of [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP-gamma-S) to the associated G-proteins. MRS-1191 with a KB value of 92 nM, proves to be highly selective for human A3 receptor vs human A1 receptor-mediated effects on adenylate cyclase[1].
[1]. Jacobson KA, et al. Pharmacological characterization of novel A3 adenosine receptor-selective antagonists. Neuropharmacology. 1997 Sep;36(9):1157-65.