ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: Metal selectivity of exocytosis was analyzed by comparing the effects of polyvalent metal cations Ca2+, Ba2+, Sr2+, Pb2+, La3+, Cd2+, Co2+, Tb3+, Mn2+, and Zn2+ on the release of norepinephrine (NE) from staphylococcal α-toxin-permeabilized bovine chromaffin cells. Pb2+, La3+, Cd2+, Sr2+, and Ba2+ activated NE secretion accompanied by the release of intragranular dopamine β-hydroxylase but not cytosolic lactate dehydrogenase, indicating the activation of the mechanism of exocytosis. The release triggered by saturating concentrations of Pb2+, La3+, Cd2+, and Sr2+ was nonadditive with Ca2+, indicating a common site of action. In contrast, the Ba2+-evoked NE release was additive with Ca2+ and the Ca2+ agonists Pb2+, La3+, Cd2+, and Sr2+, suggesting that Ba2+ activates secretion at a site distinct from the Ca2+ receptor. In distinction to the NE release evoked by Pb2+, La3+, Cd2+, and Ba2+, the Sr2+-evoked NE release was associated with a significant elevation of Ca2+ concentration in the medium and abolished by Ca2+ chelation. This indicates that the secretagogue effect of Sr2+ was indirect and secondary to the displacement of bound Ca2+. Co2+ and Mn2+ inhibited the NE release evoked by Ca2+, Sr2+, Pb2+, La3+, and Cd2+ but had no effect on the Ba2+-dependent secretion. Tb3+ and Zn2+ were without effect on exocytosis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1471-4159.1996.66020644.x
