Imidazoline 1 (I1) Receptor Ligands

Imidazoline 1 receptors (I₁) (labeled by clonidine) are members of the imidazoline family of receptors, which also include I₂ (labeled by idazoxan) and I₃ receptors. I₁ receptors are localized to the plasma membrane and are found in the lateral reticular nucleus, locus coeruleus, kidney, pancreas and on platelets.

I₁ activation is coupled to choline phospholipid hydrolysis, leading to the generation of diacylglyceride, arachidonic acid and eicosanoids. Also, I₁ may inhibit the Na⁺,H⁺ exchanger.

Physiological roles of the I₁ receptor include lowering blood pressure, renal osmolar clearance, central control of intraocular pressure and the electrophysiological response to hypoxia.