However, the brevetoxins were not included in the present study, as the neuro-2a bioassay is already able to discriminate between the presence of DSPs and the neurotoxic brevetoxins, i.e., DSPs can be detected without addition of ouabain and
veratridine, while the brevetoxins can only be detected in the neuro-2a bioassay by adding low concentrations of ouabain and
veratridine (Manger et al., 1995; Dickey et al., 1999).
A previous study of adult acutely dissociated rat thalamic neurons depolarized by exposure to
veratridine or monensin found that the resulting [Na.sup.+] influx resulted in an increase in Na/K pump density and in the level of phosphorylated pump molecules (implying increased pump activity; [37]).
Veratridine evokes release of calcitonin gene-related peptide from capsaicin-sensitive nerves of rat urinary bladder.
TTX was purchased from Tocris Bioscience (Ellisville, MO) and veratridine was from Sigma-Aldrich (St.
The maximum responses for [Na.sup.+] influx produced by pyrethroids were all lower than that of 10 [micro]M veratridine (Figure 1A), a plant-derived sodium channel neurotoxin site 2 agonist.
Extracts of ZJW and RC and berberine, palmatine and jatrorrhizine, components of RC, all inhibited CA secretion and rise in [[[Ca.sup.2+]].sub.i] induced by acetylcholine (ACh), veratridine (Ver) and/or 56 mM [K.sup.+].
Reagents were obtained from the following sources: Eagle's minimum essential medium (MEM) and new born calf serum from Gibco (USA); collagenase from Nitta Zerachin (Osaka, Japan); acetylcholine and veratridine from Sigma (St.
In response to stimulation by
veratridine, a secretagogue (a substance that induces secretion) that targets voltage-gated [Na.sup.+] channels, the release rate and the total amount of ACh released were significantly lower, by 10-fold, than the response induced by KCl.
Toxin T46 from Gymnodinium breve (formerly Ptychodiscus brevis) enhances activation of voltage-sensitive sodium channels by
veratridine. Mol Pharmacol 19:345-348.
Brill, D., M., Wasserstorm, J.A.: Intracellular sodium and positive inotropic effect of
veratridine and cardiac glycoside in sheep perkinje fibers.
Catterall WA, Risk M 1980, Toxin t4-6 from Ptychodiscus brevis (formerly Gymnodinium breve) enhances activation of voltage-gates sodium channels by
veratridine. Mol Pharmacol 19:345-348.
Toxin T48 from Ptychodiscus brevis (formerly Gymnodinium breve) enhances activation of voltage-sensitive sodium channels by
veratridine. Mol Pharmacol 19:345-348 (1981).