Open AccessEnhanced Release of Dopamine-β-Hydroxylase from Sympathetic Nerves by Calcium and Phenoxybenzamine and Its Reversal by Prostaglandins
Author(s) -
David G. Johnson,
Nguyen B. Thoa,
Richard M. Weinshilboum,
Julius Axelrod,
Irwin J. Kopin
Publication year - 1971
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.68.9.2227
Subject(s) - phenoxybenzamine , vas deferens , dopamine , medicine , endocrinology , chemistry , norepinephrine , exocytosis , catecholamine , calcium , free nerve ending , neurotransmitter , biology , central nervous system , secretion , propranolol
Dopamine-β-hydroxylase (EC 1.14.2.1), an enzyme localized in sympathetic synaptic vesicles, was released together with norepinephrine duringin vitro stimulation of the hypogastric nerve that innervates the vas deferens of the guinea pig. Stimulation of the nerve in the presence of high concentrations of calcium (7.5 mM) or phenoxybenzamine caused a marked increase in the amounts of the enzyme and norepinephrine released into the bath. The augmentation of release of dopamine-β-hydroxylase by 7.5 mM calcium or phenoxybenzamine was reversed by prostaglandin E2 . These findings suggest that the release of the sympathetic neurotransmitter, norepinephrine, occurs by a process of exocytosis in which the vesicular content of soluble dopamine-β-hydroxylase is also released. The depolarization-induced exocytosis, which is stimulated by calcium, may be affected by prostaglandin E2 or phenoxybenzamine through inhibition or enhancement of the actions of calcium in the release process.