HETEROGENEITY OF IMIDAZOLINE BINDING-SITES REVEALED BY A CIRAZOLINE DERIVATIVE

The affinity of AMPI (2-[3-aminophenoxy]methyl imidazoline) for [H-3]c lonidine and [H-3]idazoxan imidazoline binding sites was determined in various rabbit and human tissues. Although cirazoline showed a high a ffinity (nM range) in all the tested tissues, its derivative, AMPI, ha d a high affinity (nM range) in rabbit brain and kidney but a low affi nity (mu M range) in the human brain. These differences in affinities were very similar to those obtained with amiloride. The same results w ere obtained when considering [H-3]clonidine or [H-3]idazoxan specific imidazoline binding sites.