Botulinum toxin types A, B and D inhibit catecholamine secretion from bovine adrenal medullary cells.

Evoked catecholamine secretion from cultured bovine adrenal medullary cells is inhibited by commercially available botulinum toxins - types A, B and D (10(4)-10(6) MLD/ml of culture medium). Basal secretion is also inhibited. The catecholamine content of such toxin-treated cells is larger than that of control cells and may in part be a result of the inhibition of basal release. The onset of action of botulinum toxin types A and D can be neutralised by their respective antisera. Concentrations of botulinum toxins A, B or D that inhibit secretion leave unaffected the 45Ca2+ influxes normally associated with secretion. These data provide further evidence to support the idea [(1985) Nature 317, 719-721] that botulinum toxins block secretion by acting downstream of the Ca2+ transient at or near the site of exocytosis.