Chloride and magnesium dependence of vasopressin release from rat permeabilized neurohypophysial nerve endings.
The role of Cl- and Mg+ ions has been studied on the secretory mechanism leading to the release of vasopressin from digitonin permeabilized nerve endings isolated from the rat neurohypophysis. Secretion was triggered by challenging the permeabilized nerve endings with 1.1 microM free Ca2+. Magnesium enhances secretion and its maximal effect occurred at a concentration of about 2 mM. Further increase of this divalent cation concentration however led to an inhibition of secretion. Chloride ions are necessary for the final steps in exocytosis and this effect of Cl- was inhibited by the chloride channel antagonist N144. It is concluded that in neurosecretory nerve endings magnesium and chloride ions are crucial components for exocytosis to occur.
Dayanithi
G
G
Centre de Neurochimie, Strasbourg, France.
Nordmann
J J
JJ
D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002712:Chlorides / Q000494:pharmacology* / Q000502:physiology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology* / Q000502:physiology; D009411:Nerve Endings / Q000187:drug effects / Q000378:metabolism*; D010904:Pituitary Gland, Posterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats
D002712:Chlorides; D001127:Arginine Vasopressin; D008274:Magnesium