title: Storage and release of acetylcholine in the isolated superior cervical ganglion of the rat.
abstract: 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 KCl) 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 continuous 10/sex stimulation. A drastic depression in the acetylcholine release is described which is related to the time of preincubation of the ganglia with eserine prior to stimulation. Indeed, a 30 min exposure to eserine, compared with a 5 min period, resulted in a 4-fold decrease in the steady output rate. Under optimal conditions, the initial volley output at 10/sec was 1.3 X 10(-4) of the releasable transmitter pool and 1.9 X 10(-4) during the steady-state output. These results are discussed in the light of the electrophysiological knowledge of the quantal release process at the ganglionic synapse.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002794:Choline / Q000378:metabolism; D004558:Electric Stimulation; D005725:Ganglia, Autonomic / Q000187:drug effects / Q000378:metabolism*; D006426:Hemicholinium 3 / Q000494:pharmacology; D008297:Male; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D013997:Time Factors
chemical_list: D006426:Hemicholinium 3; D010830:Physostigmine; D002794:Choline; D000109:Acetylcholine