Decline of Tissue Noradrenaline under the Influence of a Mitotic Inhibitor

Abstract

MATERIALS are transported down axons by two processes: a slow process of bulk axoplasmic flow moving at 1–6 mm/day and a fast transport process which is thought to be mediated by neurotubules and moves at 10²–10³ mm/day¹. Drugs such as colchicine, which inhibit mitosis by interfering with the formation of the mitotic spindle, interact also with neurotubules, indicating that the neurotubule and the mitotic spindle may be homologous structures². Colchicine inhibits both fast³ and slow⁴ intra-axonal protein transport, suggesting that neurotubules may be associated with both processes. Granules containing noradrenaline are transported down sympathetic nerves by a fast process⁵ which is inhibited by local application of colchicine⁶. Vinblastine, a mitotic inhibitor used in the treatment of certain cancers, affects formation of neurotubules⁷, and we have injected vinblastine intravenously into rats in an attempt to interfere with the intra-axonal transport of noradrenaline in sympathetic nerves generally.