Abstract: Anisodine, a new alkaloid, isolated from the root of Scopolia tangutica Maxim.differs from scopolamine by the presence of one extra hydroxyl group on the tropic acid moiety. The influence of Anisodine on the release and synthesis of Ach by slices of rat brain cortex was studied.Brain slices were incubated in a medium containing the irreversible cholinesterase inhibitor soman and high concentration (25 mM) of KCl and the release and synthesis of Ach were determined by bioassay on the dorsal leech muscle. During aerobic incubation at 37℃ in a medium containing soman with 4.7 mM KCl, Ach was synthesized actively, and both the release and synthesis increased when the potassium concentration of the medium was raised to 25 mM.In a high KCl medium, the addition of Anisodine in concentrations of 8×10^-7, 8×10^-8. 8×10^-9 and 8×10^-10 M, further enhanced the release, and in concentrations of 8×10^-8 and 8×10^-9 M, increased the synthesis of Aeh. However, when the Anisodine concentration was 8×10^-7 M the release of Ach increased, whereas tissue Ach content decreased. This may be due to inhibition of reuptake at high concentration ofAnisodine. The fact that Anisodine at 8×10^-11 M slightly but significantly decreased the content of Ach in the tissue remains to be explained.