[Bioassay for acetylcholine from the rat cervical sympathetic ganglion (author's transl)]

1. A bioassay for acetylcholine (Ach), with a sensitivity of 0.1 picomoles in 30 microliters (microliter) (Fig. 3), was developed using the powerful musculature of the common leech (Haemopis sanguisuga). 2. Ach was extracted from a pool of ganglia with sodium tetraphenylborate in 3-heptanone and analysed using gas chromatography. The chromatograph confirmed that the "Ach like effect" measured with bioassay was due to acetylcholine and not to one of its derivatives (Fig. 5 and 6). 3. An incubation chamber for perfusing the isolated superior cervical ganglion of the rat is described, with which it is possible to do electrophysiological experiments and to sample the Ach lost or released by the ganglion (Fig. 2). 4. Using this system, the results obtained from the resting or stimulated rat ganglion incubation in-vitro, were similar to those obtained with the cat ganglion perifused in situ. 5. Experiments were also performed to investigate the effect of removing the two precursors of Ach, glucose (Table I) and choline (Fig. 9), from the incubation medium.