The alkaloid 6-benzoylheteratisine inhibits voltage-gated Na+ channels in rat brain synaptosomes.

The effects of the Aconitum alkaloid 6-benzoylheteratisine on the aconitine-, veratridine-, oubain- and KCl-induced alterations in free synaptosomal Na + ([Na+]i) and Ca2+ ([Ca2+]i) and the release of endogenous glutamate from rat cerebrocortical synaptosomes were investigated. [Na+]i and [Ca2+]i were fluorometrically determined employing SBFI and Fura-2 as the Na+ and Ca2+ sensitive dyes, respectively. Glutamate was detected by a continuous enzyme-linked fluorometric assay.

Mode of antinociceptive and toxic action of alkaloids of Aconitum spec.

Extracts of the plant Aconitum spec. are used in traditional Chinese medicine predominantly as anti-inflammatory and analgesic agents, the latter allegedly equally potent as morphine but without any habit-forming potential. As the only pharmacologically active compounds, the C19 diterpenoid alkaloid aconitine, and some of its derivatives, have been proven to be antinociceptive in different analgesic assays, but the mode of action is unknown.

Aconitum sp. alkaloids: the modulation of voltage-dependent Na+ channels, toxicity and antinociceptive properties.

Alkaloids from Aconitum sp., used as analgesics in traditional Chinese medicine, were investigated to elucidate their antinociceptive and toxic properties considering: (1) binding to Na+ channel epitope site 2, (2) alterations in synaptosomal Na+ and Ca2+ concentration ([Na+]i, [Ca2+]i), (3) arrhythmogenic action of isolated atria, (4) antinociceptive and (5) acute toxic action in mice. The study revealed a high affinity group (Ki 1 microM) and a low affinity group (Ki 10 microM) of alkaloids binding to site 2.