Abstract: Trifunctional agents useful as inhibitors of A.sub.1 -Adenosine receptors may be formulated into pharmaceutical compositions. These agents are represented by formula (I): ##STR1## wherein X is CH or N, R is an isothiocyanate group, an amino group or --NHCO.sub.2 C(CH.sub.3).sub.3 and R.sup.1 is hydrogen, carboxyl, lower alkoxycarbonyl, aminocarbonyl, ##STR2## lower alkyl, optionally substituted with: --OH, --COOH, lower ester of COOH, carboxamide, NHCOCH.sub.3, NHCOCH.sub.2 Br, halo, dimethylamino, triethylammonium, NHCONH.sub.2, SO.sub.2 NH.sub.2, --SO.sub.3 H, or a reporter group, particularly a spectroscopic reporter group such as a fluorescent dye, photoaffinity probe, or spin label probe, coupled through an amide, sulfonamide, amine or thiourea linkage, biotinylamino- (optionally containing an .epsilon.-aminocaproyl spacer chain or similar spacer chain) or; R.sup.1 is CONH--R.sup.2 or NHCSNH--R.sup.2, wherein R.sup.