The effect of hemicholinium-3 on choline and acetylcholine levels in a sympathetic ganglion.
Pregangliaaonic stimulation of the cat's superior cervical ganglion in the presence of hemicholinium-3 (HC-3) produced the expected depletion of acetylcholine (ACh) stores, but failed to cause a corresponding reduction in the choline content. These results suggest that either HC-3 possesses an intracellular site of action or that in lower doses it selectively inhibits a specialized choline transport system in cholinergic nerves. At a dose of 2 mg/kg, HC-3 probably blocked ACh synthesis completely in ganglia stimulated at 20 Hz. Under these conditions, there was a rapid depletion of ACh to about 50% of control levels during the first 5 min of stimulation and thereafter the rate of decline in ACh levels proceeded at a much slower pace. Since the 2 mg/kg dose of HC-3 did not raise plasma choline concentrations, it may be assumed that non-specialized choline transport systems in other tissues were not significantly inhibited by this dose of HC-3. However, when the dose of HC-3 was increased to 4 mg/kg, plasma choline levels increased by 58%.
D000109:Acetylcholine / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D002415:Cats; D002794:Choline / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005725:Ganglia, Autonomic / Q000032:analysis / Q000187:drug effects*; D006426:Hemicholinium 3 / Q000008:administration & dosage / Q000494:pharmacology*; D010275:Parasympathetic Nervous System / Q000187:drug effects; D013268:Stimulation, Chemical; D013997:Time Factors
D006426:Hemicholinium 3; D002794:Choline; D000109:Acetylcholine