1970 Volume 20 Issue 4 Pages 504-508
The concept of two adrenergic receptor mechanisms or α- and β-adrenergic receptor systems, originally proposed by Ahlquist (1) was based on orders of potency of a series of catecholamines. Since dichloroisoprenaline (DCI) was introduced as a new category of drugs that selectively blocked the response due to β-adrenergic activation, several β-adrenergic blockers were found. In this paper 2-(2-hydroxy-3-tert-butylaminopropoxy) chlorobenzene hydrochloride (D-69-12) has been found to be a potent β-adrenergic blocker. However, D-69-12 in very high concentrations relaxed the smooth muscle preparations. So mode of action of D-69-12 was examined. Furthermore, the dual action of D-69-12 on the smooth muscle preparations has been discussed in this paper.
