Choline uptake in cholinergic nodose cell bodies.
Isolated living cell bodies were obtained by mechanical and enzymatic dissociation from adult rabbit nodose ganglion followed by separation of fibres and cells using a Percoll gradient. A purification yield of 45% was measured. Based on previous results obtained in whole ganglion and showing the presence of cholinergic cell bodies among the afferent fibres of the vagus nerve, this preparation was used to study choline uptake by neuron cell somata. Cholinergic cells counted after choline acetyltransferase immunohistological staining showed a stained population of 2.9% among the isolated population. Two [3H]choline uptake mechanisms were detected at the cell body level. The first, with Km1 = 7 microM and Vm1 = 200 pmol/h per ganglion is sodium dependent, related to acetylcholine synthesis (43%) and has an IC50 with hemicholinium-3 equal to 50 microM. The second, with Km2 = 54 microM and Vm2 = 2235 pmol/h per ganglion is sodium independent, poorly associated to acetylcholine synthesis (12%) and exhibits an IC50 of 2 microM with hemicholinium-3. Except for their sensitivity to hemicholinium-3, the high and low affinity choline uptake mechanisms observed at the somatic level have, respectively, the same characteristics as the high and low affinity mechanisms described at the synaptic level. Their physiological role, their opposed sensitivity to hemicholinium-3 compared to the synaptic uptake systems and the relation between the somatic high affinity choline transport and an acetylcholine somatic release are discussed.
CNRS UPR 148, Marseille, France.
B
B
Palouzier-Paulignan
M C
MC
Chamoin
J P
JP
Ternaux
D000109:Acetylcholine / Q000096:biosynthesis; D000818:Animals; D002469:Cell Separation; D002794:Choline / Q000493:pharmacokinetics*; D002795:Choline O-Acetyltransferase / Q000032:analysis; D006426:Hemicholinium 3 / Q000494:pharmacology; D007150:Immunohistochemistry; D009474:Neurons / Q000201:enzymology / Q000378:metabolism*; D009620:Nodose Ganglion / Q000166:cytology / Q000378:metabolism*; D010275:Parasympathetic Nervous System / Q000166:cytology / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology
D006426:Hemicholinium 3; D012964:Sodium; D002795:Choline O-Acetyltransferase; D002794:Choline; D000109:Acetylcholine