[Imidazoline-guanidine site: a subtype of imidazoline receptors].

Since the demonstration that imidazoline and guanidinium alpha-2 adrenergic agonists induce some of their functional effects by a "nonadrenergic" mechanism, many efforts have been done to identify an imidazoline receptor. Binding studies have allowed to characterize two classes of potential imidazoline receptors: the "(p-amino)clonidine" and the "idazoxan" binding sites. These last, that we named "imidazoline-guanidinium receptive sites" (IGRS) on the basis of their ligand-recognition properties, have been identified, for the first time, in the proximal tubule from rabbit and human kidney. In the present report we will summarize the studies that led us to the characterization of IGRS.