QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by NORMANN, T. C. Search for Related Content PubMed PubMed Citation Articles by NORMANN, T. C.

Journal of Experimental Biology 61,401-409 (1974)
Published by Company of Biologists 1974

Calcium-Dependence of Neurosecretion by Exocytosis

TOM CHRISTIAN NORMANN ¹

¹ Institute of General Zoology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen , Denmark; Department of Zoology, University of Cambridge, Downing Street, Cambridge, England

Exocytosis of neurosecretory granules in the corpus cardiacum of the blowfly Calliphora erythrocephala was induced both by electrical stimulation and by depolarization with K⁺. This secretory activity was quantitatively determined by the frequency of omega figures and vesicle clusters, which are the ultrastructural indications of two distinct phases of the exocytotic process. Experimentally elicited exocytosis was reduced when Ca²⁺ were omitted from the bathing medium. This result supports the idea that the coupling between excitation (depolarization) and exocytosis involves Ca²⁺ influx through the axolemma. Barium effectively substitutes for calcium in the secretory process. High levels of magnesium in the bathing medium, however, decreased exocytosis, possibly by interfering with calcium influx.