Uptake of [N-Me-3H]-choline by synaptosomes from the central nervous system of Locusta migratoria.
The accumulation of 3H-choline by isolated synaptosomes from the central nervous system of locust was studied at concentrations varying from 0.05 to 40 microM. Kinetic analysis of the saturable process revealed a high-affinity and a low-affinity system. The high-affinity uptake was competitively inhibited by hemicholinium-3 and was absolutely dependent on external sodium. Elevated potassium concentrations inhibited choline uptake. The choline uptake by insect synaptosomes was found to be remarkably resistant to a variety of metabolic inhibitors. The reduced choline uptake under depolarizing conditions (high potassium concentration or veratridine) in the absence of calcium implies that electrochemical gradients are important for high-affinity choline uptake. Depolarization of preloaded synaptosomes under appropriate conditions resulted in a significant release of newly accumulated choline radioactivity.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002490:Central Nervous System / Q000378:metabolism*; D002794:Choline / Q000378:metabolism*; D006110:Grasshoppers; D006651:Histocytochemistry; D007700:Kinetics; D008854:Microscopy, Electron; D012965:Sodium Chloride / Q000494:pharmacology; D013574:Synaptosomes / Q000378:metabolism* / Q000648:ultrastructure; D014316:Tritium
D014316:Tritium; D012965:Sodium Chloride; D002794:Choline