Uptake and metabolism of choline by the embryonic heart of the chick in vitro.
1. The uptake and metabolism of [14C]choline was investigated in isolated hearts from 4- to 14-day-old chick embryos. 2. A high-affinity uptake system of choline was present in hearts from all ages of embryos examined: the Km values were 9-11 muM, while the Vmax values ranged from 5 (14-day ventricles) to 77 (4-day atria) pmol choline/mg protein/min. 3. Hemicholinium-3, metabolic inhibitors, low temperature and low Na+ concentrations reduced the high-affinity uptake process. 4. The accumulated choline was converted mainly into phosphorylcholine in 4-day hearts, while the percentage of conversion into acetylcholine increased in older embryos.
D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D002642:Chick Embryo; D002794:Choline / Q000378:metabolism*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D003080:Cold Temperature; D005971:Glutamates / Q000378:metabolism; D006426:Hemicholinium 3 / Q000494:pharmacology; D007700:Kinetics; D009124:Muscle Proteins / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism
D000963:Antimetabolites; D005971:Glutamates; D009124:Muscle Proteins; D006426:Hemicholinium 3; D012964:Sodium; D002795:Choline O-Acetyltransferase; D002794:Choline; D013936:Thymidine