[Effects of atropine on acetylcholine levels in the rat iris-ciliary body]

In an attempt to estimate the in vivo acetylcholine level in rat iris-ciliary body, animals were sacrificed by microwave irradiation which rapidly inactivates metabolic enzymes. Acetylcholine levels in the iris-ciliary body were determined by high-performance liquid chromatography with electrochemical detection. The acetylcholine level in rat iris-ciliary body per gram tissue protein was 58.8 +/- 5.0 nmol/g (mean +/- SEM, n = 9). A single instillation of 5 microliters of an 0.05% atropine to one eye of a rat decreased acetylcholine level in the iris-ciliary body by 17% half an hour after administration (p less than 0.02).