RT Journal Article SR Electronic T1 ULTRASTRUCTURAL CYTOCHEMISTRY AND PHARMACOLOGY OF 5-HYDROXYTRYPTAMINE IN ADRENERGIC NERVE ENDINGS. I. LOCALIZATION OF EXOGENOUS 5-HYDROXYTRYPTAMINE IN THE AUTONOMIC NERVES OF THE RAT VAS DEFERENS JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 264 OP 271 VO 166 IS 2 A1 JAIM-ETCHEVERRY, GUILLERMO A1 ZIEHER, LUIS MARÍA YR 1969 UL http://jpet.aspetjournals.org/content/166/2/264.abstract AB Pharmacologic and electron microscopic cytochemical procedures were performed in the rat vas deferens in order to study the localization of exogenously administered 5-hydroxytryptamine (5-HT) in adrenergic nerve endings. Exogenous 5-HT accumulated in the nerve terminals was not incorporated into the intravesicular compartment, demonstrating that it is unable to displace norepinephrine from this storage site. Administration of α-methyl-m-tyrosine markedly reduced the norepinephnine content of the vas deferens as well as the dense cores of the granulated vesicles of nerve endings. The administration of 5-HT to α-methyl-m-tyrosine-pretreated rats resulted in a marked increase of 5-HT concentration in the organ and in the reappearance of the dense cores of both types of vesicles observed within the endings. That these cores corresponded to 5-HT was confirmed by the results of cytochemical tests. These data siggest that, under appropriate conditions, 5-HT can be incorporated and stored in the intravesicular compartment of the postganglionic sympathetic nerve endings normally storing norepmepllnine. © 1969 by The Williams & Wilkins Co.