Inotropic agents

Compounds of the formula ##STR8## and their pharmaceutically acceptable salts, wherein two of A.sub.1, A.sub.2, A.sub.3, and A.sub.4 are N, and the remaining A.sub.1, A.sub.2, A.sub.3, and A.sub.4 are CH, and each of R.sub.1, R.sub.2, and R.sub.3 is independently hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, allyloxy, benzyloxy, (C.sub.1 -C.sub.4 alkyl)thio, (C.sub.1 -C.sub.4 alkyl)sulfinyl, (C.sub.1 -C.sub.4 alkyl)sulfonyl, hydroxy, halo, cyano, amino, mono- or di-(C.sub.1 -C.sub.4 alkyl)amino, trifluoromethyl, or Z-Q-substituted C.sub.1 -C.sub.4 alkoxy, wherein Q is oxygen, sulfur, sulfinyl, sulfonyl, or a bond, and Z is C.sub.1 -C.sub.4 alkyl, phenyl or phenyl substituted with halo C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, nitro, amino, C.sub.1 -C.sub.4 alkylthio, C.sub.1 -C.sub.4 alkylsulfinyl, or C.sub.1 -C.sub.4 alkylsulfonyl, with the proviso that R.sub.1, R.sub.2, and R.sub.3 may not all be hydrogen at the same time.