Storage and release of acetylcholine in the isolated superior cervical ganglion of the rat

The storage and release of acetylcholine and choline were studied in the isolated superior cervical ganglion of the rat by a radioenzymic method. The acetylcholine and choline contents were 202.2 ± 5.1 and 624.7 ± 20.2 pmole/ganglion, respectively. The transmitter tissue store was unaffected during 1 h of superfusion in choline-Krebs solution, while a 20% decrease was exhibited after 2 h and then remained approximately stable. Conversely, choline content declined to 50% within 1 h and further to 37% of the original level by 4 h. About 24% of the choline assayed in the intact preparation is located in the connective sheath. Preganglionic nerve stimulation at 10-20/sec or potassium stimulation (40 mM KCI) invariably decreased the transmitter tissue stores by 25-45%; such a depletion is independent of the presence or absence of external choline. By contrast, the presence of choline proved to be a prerequisite for the efficient release of acetylcholine from eserinized ganglia during contin...