in conclusion , the failure of idazoxan to block the inhibitory effects of 6-fna , while exerting a potent competitive antagonism of clonidine-induced inhibitory effects , supports the proposal that alpha 2-adrenoceptors may in fact be subdivided into two subclasses , involving imidazoline and phenylethylamine recognition sites .
C0009014
clonidine
C1449836
imidazoline