ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: The quantitative autoradiographic L-[1–14C]leucine method for the determination of regional rates of cerebral protein synthesis in vivo takes into account recycling of unlabeled leucine derived from protein degradation into the precursor pool for protein synthesis. We have evaluated the degree of recycling by measuring the ratio of the apparent steady-state leucine specific activity in the precursor amino acid pool (tRNA-bound leucine) to that in the arterial plasma. In the whole brain of the conscious rat this ratio (λWB) equals 0.58. The equivalent ratio for leucine in the acid-soluble pool in whole brain (ΨWB) is 0.49. A first-degree polynomial equation for λWB as a function of ΨWB was fitted from paired determinations. To determine the degree of recycling in local regions of the brain, we have measured in individual brain regions (i) Ψi and calculated λi assuming that the fitted equation also applies to these localized regions. Our results indicate that the degree of recycling into the precursor pool does vary regionally; λi in the individual regions varies from 0.62 in the hypoglossal nucleus to 0.50 in the globus pallidus. Local rates of protein synthesis were then determined by the autoradiographic technique with regional corrections for recycling of unlabeled leucine. Rates of leucine incorporation into protein averaged 6.1 nmol/g of tissue/min in the brain as a whole, with the rates in gray matter about twice those in white matter.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1992.tb08324.x
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