Characterization of hormone and protein release from alpha-toxin- permeabilized chromaffin cells in primary culture

Addition of Staphylococcus aureus alpha-toxin to adult bovine
chromaffin cells maintained in primary culture causes
permeabilization of cell membrane as shown by the release of
intracellular 86Rb+. The alpha-toxin does not provoke a spontaneous
release of either catecholamines or chromogranin A, a protein
marker of the secretory granule, showing the integrity of the
secretory vesicle membrane. However the addition of micromolar free
Ca2+ concentration induced the co-release of noradrenaline and
chromogranin A. In alpha-toxin-treated cells, the released
chromogranin A could not be sedimented and lactate dehydrogenase
was still associated within cells, which provides direct evidence
that secretory product is liberated by exocytosis. By contrast,
permeabilization of cells with digitonin caused a Ca2+- dependent
but also a Ca2+-independent release of secretory product, a
dramatic loss of lactate dehydrogenase, as well as release of
secretory product in a sedimentable form. Ca2+-dependent exocytosis
from alpha- toxin-permeabilized cells required Mg2+-ATP and did not
occur in the presence of other nucleotides. Thus alpha-toxin is a
convenient tool to permeabilize chromaffin cells, and has the
advantage of keeping intracellular structures, specifically the
exocytotic machinery, intact.