The uptake of [14C] choline into synaptosomes in vitro.
1. The uptake of [(14)C]choline into synaptosomes in vitro was investigated by a gel-filtration method. Synaptosomes incubated in a medium fortified with glucose and succinate rapidly take up [(14)C]choline. 2. A substantial proportion of the radioactivity taken up can be released by osmotic shock, and is recoverable as choline on a thin-layer chromatogram. This suggests that choline is taken up across the limiting membrane into the cytoplasmic compartment of the synaptosome. 3. The concentration of choline in the synaptosome has a dependence on the external concentration of choline that is similar to that in erythrocytes and mouse cerebral-cortex slices. The choline influx has two components, one that is linear and one that is saturable with increasing choline concentration. 4. Omission of Na(+) from the incubation medium, or addition of 100mm-K(+), inhibits choline uptake. Hemicholinium no. 3 is a powerful inhibitor of the choline uptake. 5. The similarity of the choline-uptake process in synaptosomes to that in erythrocytes and cortex slices indicates that the synaptosome limiting membrane is functionally competent in this respect.
D000818:Animals; D002247:Carbon Isotopes; D002499:Centrifugation, Density Gradient; D002540:Cerebral Cortex / Q000378:metabolism; D002794:Choline / Q000378:metabolism*; D002850:Chromatography, Gel; D002855:Chromatography, Thin Layer; D003864:Depression, Chemical; D005947:Glucose; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008566:Membranes; D009995:Osmosis; D010276:Parasympatholytics / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012964:Sodium; D013386:Succinates; D013569:Synapses / Q000378:metabolism*
D002247:Carbon Isotopes; D010276:Parasympatholytics; D013386:Succinates; D012964:Sodium; D005947:Glucose; D002794:Choline; D011188:Potassium