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ANNEE : 1988

The calcium channel antagonist omega-conotoxin inhibits secretion from peptidergic nerve terminals.

AUTEURS : Dayanithi G, Moutot N, Barlier S, Colin DA, Kretz-Zaepfel M, Couraud F, Nordmann JJ.

REVUE : Biochem Biophys Res commun
N° Pubmed : 3178834

The binding of omega-conotoxin to isolated rat neurohypophysial nerve terminals, its effect on the depolarization-induced increase of cytoplasmic Ca2+ and on the potassium and electrically-induced release of vasopressin (AVP) have been studied. The results show that isolated neurosecretory nerve endings have calcium channels with a high affinity for omega-CgTx and that this toxin inhibits neurohormone release at very low concentration (IC50 = 0. 1nM). Although secretion of vasopressin is inhibited to a great extent by the toxin it is shown that a small but significant amount of the depolarization-induced AVP release is insensitive to omega-CgTx and to the dihydropyridine molecule nicardipine.