Maxadilan binds to membrane fractions of brain tissue

Maxadilan is a potent vasodilator peptide isolated from salivary glands extracts of the hematophagous sand fly. Besides effects on the cutaneous vasculature, it has also been shown to relax rabbit aortic rings while elevating levels of cAMP. As a result of the effects on the skin and aorta, it was elected to undertake an examination of the tissue distribution of binding sites for maxadilan. In addition to specific binding in rabbit aorta and spleen, binding was detected in brain from various species including human, bovine, rabbit, rat and mouse with a kD of between 85 and 201 pM. Competitive displacement of [125I] maxadilan by a number of known vasoconstrictor peptides, vasodilator peptides and small molecule receptor ligands did not occur in the rabbit brain preparation. These results suggest the presence of specific binding sites in mammalian tissue for maxadilan whose endogenous ligand remains unknown.