ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
—The activity of glutamate decarboxylase (GAD, EC 4.1.1.15) in normal and neoplastic rat tissues was determined by two assay methods, one based on the production of 14CO2 from [14C]glutamic acid and the other on the fluorimetric measurement of γ-aminobutyric acid (GABA) formation. Activities obtained with the isotopic assay were high in every tissue (ranging from over 800 in liver and brain to 107nmol CO2/min/g in lung). They were drastically diminished by Triton X-100, by an oxygen-free atmosphere or by the mitochondrial electron transport inhibitors, rotenone and antimycin A. Activities measured fluorimetrically were significant in only a few tissues and were stimulated by Triton (e.g. from 299 to 569 nmol GABA/min/g brain) but were unaffected by rotenone. For several tissues after Triton treatment the fluorimetric and isotopic assays (in air) gave the same results (i.e. the two end products, CO2 and GABA were in stoichiometric agreement); however, the fluorimetric assay remains the more reliable measure of GAD activity since Triton may not inhibit completely the non-GAD dependent decarboxylation of glutamate in all types of tissue preparations. The hepatic, renal and mammary tumours tested were devoid of GAD; among non-neural normal tissues, kidney, liver and, possibly, adrenal gland contained significant GAD activity. In kidney and liver the activity was 15 and 10 per cent of that in brain.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1975.tb03836.x
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