AN ANALYSIS OF SELECTIVE BETA RECEPTOR BLOCKADE

The beta adrenergic receptor blocking properties of 1-(4′-methyl-phenyl)-2-isopropylamino-propanol HCl (H 35/25), 1-(4′-methylphenyl)-2-isopropylaminoethanol - HCl (H 29/50) and 4-(2-hydroxy-3-isopropylaminopropoxy) acetanilide (ICI 50172) were compared according to their ability to block the positive chronotropic, vasodepressor and intestinal inhibitory responses to three doses of isoproterenol in the anesthetized dog. The results obtained suggest that these three agents differ in the selectivity of their beta receptor blocking actions. H 29/50 blocked all three responses to isoproterenol in the same dose range. H 35/25 blocked the vasodepressor but not the positive chronotropic or intestinal inhibitory responses to isoproterenol. ICI 50172 blocked the positive chronotropic response, the intestinal inhibitory response but not the vasodepressor response to isoproterenol. These data support the conclusion that there are beta receptor blocking agents with varying degrees of selectivity. © 1969.