ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: A method for the isolation of γ-aminobutyric acid-ergic (GABAergic) and glutamatergic terminals from crustacean muscle was developed, using differential centrifugation and sucrose density gradient centrifugation. Individual fractions were assessed using a variety of markers. One fraction was isolated which showed 40-fold purification of glutamate decarboxylase with a yield of 12%. This fraction was enriched in GABA, glutamate, glutamate dehydrogenase, and 5′-nu-cleotidase, but not in NADPH cytochrome c reductase. This fraction possessed an uptake system for GABA and glutamate with apparent kinetic constants of Km= 50 μM, Vmax= 250 pmol/min/mg of protein and Km - 183 μM, Vmax= 219 pmol/min/mg of protein, respectively. Electron microscopy showed nerve terminal profiles and a heterogeneous population of membrane vesicles. This fraction contained 3.4 nmol ATP/mg of protein which was stable for 30 min at 12°C, and was also able to synthesise ATP from exogenous adenosine. The terminals released labelled GABA and glutamate in a Ca2+-dependent fashion on depolarisation. No release of ATP was detected. It is concluded that viable nerve terminals have been isolated which could be used as model systems for the study of GABAergic and glutamatergic neuro-chemistry.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1989.tb08548.x
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