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 α 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 α 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 non-adrenergic fast response of the sympathetic transmission of the vas deferens.
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