title: High affinity choline uptake and calcium-dependent acetylcholine release in proteoliposomes derived from rat cortical synaptosomes.
abstract: Proteoliposomes were prepared from rat cortical synaptic plasma membranes that retained high and low affinity choline transport. High affinity transport was inhibited by hemicholinium-3 in a competitive manner and was apparently dependent on membrane potential or ion gradients. Proteoliposomes supplemented with an acetylcholine-generating system were able to synthesize [3H]ACh de novo from [3H]choline taken up by high or low affinity transport; however, we were able to specifically load proteoliposomes derived from cholinergic membranes by using a low choline concentration. [3H]ACh, but not [3H]choline, was subsequently released in a calcium-dependent manner by K+ depolarization. This preparation offers a simplified membrane system for studying functional high affinity choline transport and nonvesicular ACh release.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000378:metabolism*; D002794:Choline / Q000378:metabolism*; D007700:Kinetics; D008081:Liposomes; D008297:Male; D008854:Microscopy, Electron; D010713:Phosphatidylcholines / Q000378:metabolism; D011510:Proteolipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000378:metabolism*; D014316:Tritium
chemical_list: D008081:Liposomes; D010713:Phosphatidylcholines; D011510:Proteolipids; C020485:proteoliposomes; D014316:Tritium; D002794:Choline; D000109:Acetylcholine; D002118:Calcium