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81.
DEMONSTRATION OF ACETYLCHOLINE RELEASE BY MEASURING EFFLUX OF LABELLED CHOLINE FROM CEREBRAL CORTICAL SLICES 总被引:4,自引:2,他引:2
Abstract— To demonstrate release of ACh in the absence of inhibition of cholinesterase, slices of cerebral cortex were incubated with [3 H]choline, after which they were placed in a tissue bath for superfusion. Hemicholinium (HC-3) increased the spontaneous efflux of [3 H]choline. Electrical stimulation at 4/s increased the efflux of [3 H]choline to the same extent whether the slices were stimulated early or late during superfusion. The effect of stimulation on efflux of [3 H]choline was abolished by tetrodotoxin and by the absence of calcium. The extent of choline efflux resulting from stimulation, as calculated from the specific radioactivity of the incubation medium, was the same when the slices were incubated with 0.1 or 1.0mM choline, but was less with lower concentrations of choline. We conclude that the increased efflux of [3 H]choline evoked by stimulation probably originates from stores of [3 H]ACh synthetized during incubation. 相似文献
82.
Summary Autoradiography was found to be a useful method for studying the function of mitochondria. It might provide means to investigate the mitochondrial ATP-ase activity. Applying this method, different problems of metal salt-techniques, firstly the aspecific reactions, can be eliminated. The incubation solution contained 3H-ATP at 100 c activity. The autoradiographic precipitate seems to appear on the membrane of the mitochondria and in the intracristal space. Atractylate treatment inhibits completely the permeation of 3H-ATP. So-called arreactive mitochondria with retained structure lacking of reaction-precipitate were found besides the mitochondria revealing pronounced activity. This might refer to the manifestation of a functional state. Experiments with P32 ATP may contributs to the more exact determination of original place of the enzyme. 相似文献
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J Matkó I Seres S Papp B Somogyi 《Biochemical and biophysical research communications》1984,122(2):649-655
The quenching of coenzyme fluorescence in glycogen phosphorylase b is reinvestigated. Data with anionic quenchers show deviations from the original Stern-Volmer kinetics. A kinetic analysis based on measured lifetime data indicates a collisional quenching process, which is, however, not diffusion-controlled. It is proposed, that the quenching takes place primarily by enzyme-bound quencher species. The observed inhibition of the enzyme reaction by I- and IO-3 is consistent with this hypothesis. The inhibition pattern and spectral investigation refer to a true competition with the substrate, glucose-1-phosphate. So, this dynamic quenching can be regarded as an indicator of rapid conformational fluctuations which bring the two important active-site groups in contact. Effect of ligand binding on the quenching of coenzyme fluorescence should also be revaluated according to these results. 相似文献
86.
Our recent findings indicate that phorbol esters, the specific activators of protein kinase C induce the translocation of heavy metals (mostly: zinc) from the nucleus and mitochondria to the cytosol and microsomes of T lymphocytes. Phorbol ester treatment impairs the action of Ca-ionophores, this effect is mediated by intracellular heavy metal ions (most probably: by zinc). Zinc activates cytosolic protein kinase C, increases its affinity towards phorbol esters and contributes to its binding to plasma membranes. These results suggest that zinc may play a role in the "cross-talk" of second messengers and hence in signal transduction in T lymphocytes. 相似文献
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