title: An endogenous brain substance, CDS (clonidine-displacing-substance), inhibits the twitch response of rat vas deferens.
abstract: The effect of CDS, an endogenous brain substance that specifically displaces bound [3H]clonidine and [3H]rauwolscine in rat brain membranes and human platelets, has been tested in isolated, field-stimulated rat vas deferens. CDS, obtained after an extensive purification procedure as a single peak from an HPLC sizing column, inhibited the electrically stimulated rat vas deferens similarly to the inhibitory action of clonidine, an alpha 2-agonist. The effective dose of CDS as an inhibitor of the vas deferens is equivalent to its effective dose in displacing specifically bound [3H]-clonidine in rat brain membranes. Furthermore, the CDS inhibition of the twitch response is reversed by two alpha 2-adrenergic antagonists, yohimbine and phentolamine. From these results, it is suggested that CDS extracted from brain, with affinity for clonidine sites, may be involved in the nonadrenergic fast response of the sympathetic transmission of the vas deferens.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D003000:Clonidine / Q000378:metabolism; D004558:Electric Stimulation; D054755:Imidazoline Receptors; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D010646:Phentolamine / Q000378:metabolism; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2; D014649:Vas Deferens / Q000187:drug effects*; D015016:Yohimbine / Q000378:metabolism
chemical_list: D054755:Imidazoline Receptors; D011942:Receptors, Adrenergic, alpha; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; D003000:Clonidine; D010646:Phentolamine