N-Aralkyl substitution of 2-amino-5,6- and -6,7-dihydroxy-1,2,3,4-tetrahydronaphthalenes. 1. Cardiac and pressor/depressor activities.

Amino substitution o rigid forms of dopamine [2-amino-5,6-dihydroxy-1,2,3,4-tetrahydronaphthalene (A-5,6-DTN) and 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (A-6,7-DTN)] with aralkyl functionalities was carried out to investigate the role of such structural modifications upon cardiac inotropic/chronotropic and blood pressure activity. Derivatives of A-5,6-DTN were strong vasodepressor agents devoid action was associated with the dihydroxyphenyl-1-methylethyl derivative, which was also an inotropic selective compound. The amino substituent of dobutamine was ineffective in reducing peripheral vascular action when combined with the rigid forms of dopamine. It was also ineffective in imparting inotropic selectivity when combined with A-5,6-DTN. An analysis of these observations in light of existing structure-activity relationships of aminoaralkyl substitution of other catecholamine structure is presented.