Structural changes at pure cholinergic synaptosomes during the transmitter release induced by A-23187 in Torpedo marmorata. A freeze-fracture study.
Pure cholinergic synaptosomes isolated from the electric organ of Torpedo marmorata were stimulated by calcium ionophore A-23187. The effect of time course of stimulation on the changes in intramembrane particles (IMPs) on presynaptic membranes was studied by quick-freezing and aldehyde-fixation freeze-fracture. We showed that the decrease of small-particle density at the P-face and the increase of large-particle density at the E-face was maximum after 30 sec of A-23187 stimulation. Later, the density of synaptic vesicles decreased. We suggest that the redistribution of IMPs on the presynaptic membrane and acetylcholine (ACh) release from pure cholinergic synaptosomes have a similar time course when triggered by A-23187.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D004557:Electric Organ / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005614:Freeze Fracturing; D007700:Kinetics; D008854:Microscopy, Electron; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D014101:Torpedo
D000001:Calcimycin; D000109:Acetylcholine