Effects of choline augmentation on acetylcholine synthesis and release in rat atrial minces.
The uptake and acetylation of [3H]-choline, as well as the calcium-dependent release of a newly synthesized [3H]-ACh, was studied in a new rat atrial mince preparation. The hemicholinium-3-sensitive uptake and acetylation of [3H]-choline increased as [3H]-choline concentrations were elevated to 100 microM in atrial minces. In contrast, hemicholinium-3-sensitive [3H]-choline uptake was saturated with 15 microM [3H]-choline in brain synaptosomes. The increased atrial [3H]-ACh synthesized in the presence of [3H]-choline augmentation was releasable by 50 mM K+-depolarization in a 1 mM cobalt-sensitive manner. These results suggest that atrial parasympathetic activity may be more sensitive to circulating choline concentrations than brain cholinergic neurons are.
D000107:Acetylation; D000109:Acetylcholine / Q000096:biosynthesis*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D002794:Choline / Q000378:metabolism / Q000494:pharmacology*; D005110:Extracellular Space / Q000378:metabolism; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism*; D006426:Hemicholinium 3 / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D006426:Hemicholinium 3; D002794:Choline; D000109:Acetylcholine; D002118:Calcium