Segmental differences in the density of autonomic receptors in dog vas deferens.

In order to study the segmental difference in the density of autonomic receptors of the vas deferens, we measured the amount of adrenergic alpha 1-, alpha 2- and beta-receptors and muscarinic cholinergic receptors in the three portions (prostatic, intermediate and epididymal) of dog vas deferens using radioligand binding techniques. Saturation experiments with 3H-prazosin, 3H-yohimbine, 3H-dihydroxyalprenolol and 3H-quinuclidinyl benzilate demonstrated that three were significant amounts of adrenergic alpha 1-, alpha 2- and beta-receptors and muscarinic cholinergic receptors in the three portions of dog vas deferens. Of the three portions examined, the prostatic portion was found to have a larger amount of alpha 1-, alpha 2-receptors and muscarinic receptors, while the intermediate portion was found to have a larger amount of beta-receptors. The epididymal portion was found to have a smaller amount of autonomic receptors. These data suggest that the prostatic portion plays a more important role in the function of the dog vas deferens. It is thought that the different segments of the vas deferens have a different functional role according to the distribution of autonomic receptors.