Abstract
In the preceding paper, it was reported that 1-(3', 4', 5'-trimethoxybenzyl)-6, 7-dihydroxy-1, 2, 3, 4-tetrahydroisoquinoline (III) was the most potent bronchodilator of all the tetrahydroisoquinoline derivatives tested. Its bronchodilating activities in vitro and in vivo were about 10 times and 5 times stronger respectively than those of isoproterenol (1). In view of the general correlation between the bronchodilating and cardiovascular actions exhibited by adrenergic β-stimulants, it is interesting to study the effects of this compound on the cardiovascular system. In addition to III, we also tested two other tetrahydroisoquinoline derivatives, 1-benzyl-6, 7-dihydroxy-1, 2, 3, 4-tetrahydroisoquinoline (I) and 1-(3', 4'-ethylenedioxybenzyl)-6, 7-dihydroxy-1, 2, 3, 4-tetrahydroisoquinoline (II), for their effects on the cardiovascular system of variuos experimental animals in comparison with the actions of isoproterenol on the same system. Of the three compounds, compound III was pharmacologically the most active. Compound I having the basic structure in the chemical sense belonged to the least active group. Compound II, in which both 3'- and 4'-hydroxy groups of tetrahydroisoquinoline are masked through formation of the ethylenedioxy linkage, had an intermediate pharmacological potency.
