ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: Concentrations of [14C]2-deoxy-D-glucose ([14C]DG) and of glucose were measured in plasma of arterial and sagittal sinus venous blood from awake Fischer-344 rats at 3, 12, and 24 months of age, during continuous intravenous infusion of [14C]DG and after a steady-state arterial plasma concentration of [14C]DG was reached. Brain extraction, i.e., the difference between arterial and venous plasma concentrations divided by the arterial plasma concentration, was calculated for both [14C]DG and glucose. Because exchange of both substances between rat plasma and erythrocytes is slow, the ratio of the brain extraction of [14C]DG to that of glucose is identical to the lumped constant in the deoxyglucose procedure of Sokoloff et al. [J. Neurochem. 28, 897–916, (1977)]. This ratio equaled 0.502 ± 0.015 (SEM) at 3 months, 0.456 ± 0.007 at 12 months, and 0.418 ± 0.006 at 24 months of age (n = 15); the means differed significantly from each other (p 〈 0.05). The results indicate that the lumped constant declines between 3 and 24 months of age in awake rats, and suggest that many reported age reductions in regional cerebral glucose utilization, of 15–25%, are artifactual.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1986.tb13059.x
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