FRACTIONNEMENT DE L'ORGANE ELECTRIQUE DE LA TORPILLE: LOCALISATION SUBCELLULAIRE DE L'ACETYLCHOLINE SUBCELLULAR FRACTIONATION OF THE ELECTRIC ORGAN OF TORPEDO MARMORATA

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Abstract
Résumé— L'acètylcholine a été localisée au niveau d'une fraction de vésicules synaptiques isolée à partir de l'organe électrique; le taux d'acétylcholine est fonction de la pression osmotique du milieu. La choline‐acétyltransfèrase (EC 2.3.1.6) n'est pas associée à cette fraction. Les distributions sont comparées à celles de diverses enzymes. —The electric organ of Torpedo is a purely cholinergic tissue from which fractions of small vesicles 800 Å in diameter may be isolated by homogenisation and centrifugation. The vesicle fraction is rich in acetylcholine. The yield of acetylcholine in the vesicle fraction is dependent on the osmolarity of the homogenisation medium, 800 mosm being optimal. The isolated vesicles themselves lose acetylcholine when subjected to hypo‐osmotic conditions. Choline acetyltransferase (EC 2.3.1.6) behaves as a cytoplasmic enzyme and is not associated with the vesicular fraction. Acetylcholinesterase (EC 3.1.1.7) is found in fractions containing membrane fragments. The cellular distribution of these components of the cholinergic synapse is similar in Torpedo electric organ and mammalian cortex.