Quantal transmitter release by glioma cells: quantification of intramembrane particle changes.

Glial cells in situ are able to release neurotransmitters such as glutamate or acetylcholine (ACh). Glioma C6BU-1 cells were used to determine whether the mechanisms of ACh release by a glial cell line are similar or not to quantal release from neurones. Individual C6BU-1 cells, pre-filled with ACh, were moved into contact with a Xenopus myocyte that was used as a real-time ACh detector.

Morphological changes related to reconstituted acetylcholine release in a release-deficient cell line.

The membrane changes accompanying Ca(2+)-dependent acetylcholine release were investigated by comparing release-competent and release-incompetent clones of mouse neuroblastoma N18TG-2 cells. No release could be elicited in native N18 cells or in a N18-choline acetyltransferase clone in which acetylcholine synthesis was induced by transfection with the gene for rat choline acetyltransferase. However, acetylcholine release was operative in a To/9 clone which was co-transfected with complementary DNAs from rat choline acetyltransferase and Torpedo mediatophore 16,000 mol.

An improved approach to freeze-fracture morphology of monolayer cell cultures.

Much work is currently done on cell cultures to elucidate membrane processes associated with different cell functions. We describe here a modified freeze-fracture method to obtain systematically large fractured areas of the plasma membrane from monolayer cell culture in situ. Cells are grown until confluence on a Thermanox coverslip overlaid with poly-L-ornithine.

Binding of gold-protein ligand complexes to neurokinin receptors. visualization with the electron microscope on pig coronary artery and rat portal vein.

Active neurokinin (NK) receptors were visualized with 5-nm colloidal gold-protein-substance P (GPSP) and -senktide (GPSenk) complexes on vascular tissues. Electron micrographs of pig coronary strips incubated with GPSP showed gold particles either bound to the plasmalemma or inside intracytoplasmic vesicles of endothelial cells. Preincubation with SP or the NK1 receptor antagonist L-703606 prevented GPSP marking.

Zinc blocks acetylcholine release but not vesicle fusion at the Torpedo nerve-electroplate junction.

The combined effects of Zn2+ treatment and nerve stimulation were studied on cholinergic synapses of the Torpedo marmorata electric organ. Incubation of small pieces of electric tissue in 250 microM ZnCl2 for 2 h irreversibly blocked synaptic transmission by inhibiting the release of acetylcholine. This treatment, however, did not cause any significant fine structural alteration in the nerve-electroplate junctions.