Imidazoline binding sites were originally classified into I1 sites (labeled by clonidine) and I2 sites (labeled by idazoxan). I2 sites have been further classified into I2A (amiloride-sensitive) and I2B (amiloride-insensitive). A putative I3 has been described which enhances insulin secretion.
Imidazoline Receptor Target Files
Imidazoline receptors have a physiological role in the central regulation of blood pressure. Activation of I1 receptors decreases sympathetic tone via a central mechanism, which has a hypotensive effect and reduces plasma catecholamine levels. In contrast, I2-mediated monoamine oxidase inhibition has a hypertensive effect and increases plasma catecholamine levels.
|Location||Lateral reticular nucleus, locus ceruleus, kidney, platelets, pancreas||Interpeduncular and arcuate nuclei, pineal gland, liver, kidney, heart, striated muscle, MAO||Pancreatic β cells|
|Transduction Mechanism||↑ Diacylglycerol and arachidonic acid||Unknown||Unknown|
|Key Selective Ligands||
AGN 192403 (1072)
BU 239 (0726)
RS 45041-190 (0889)
|Putative Endogenous Ligands||Agmatine (0842), Harmane (1132)|