Determination of local rates of 45 calcium influx into rat brain by
quantitative autoradiography: studies of aging.
Dienel, Gerald A., Beth Tofel-Grehl, Carmina C. Cruz, Karen Luludis,
Karen Pettigrew, Louis Sokoloff, and Gary E. Gibson.
Laboratory of Cerebral Metabolism and Division of Epidemiology and
Services Research, National Institute of Mental Health, Bethesda, MD,
Dementia Research, Cornell University Medical College at Burke
Medical Research Institute, White Plains, NY
APStracts 2:0098R, 1995.
Calcium homeostasis in brain is altered in many conditions, but there
is no method to assay quantitatively local calcium flux into brain in
vivo. 45Ca uptake into gross-dissected brain regions was measured and
compared to results obtained with a quantitative autoradiographic
procedure developed to assay influx of 45Ca into brain. Regional
calcium contents, brain:plasma distribution ratios for calcium and
45Ca, apparent plasma-to-brain transfer coefficients, and net uptake
of 45Ca into gross-dissected regions varied by as much as 80%. Local
rates of net uptake of 45Ca into 34 structures determined by
autoradiography varied by 12-14-fold, and rates of movement of 45Ca
down concentrations gradients varied by a factor of seven. Previous
studies with gross-dissected brain regions suggested changes in
calcium uptake into brain during aging, but the values of all the
variables assayed in the present study were similar in young adult,
middle-aged, and old male rats. A quantitative autoradiographic
procedure to assay levels of 45Ca in brain provides the anatomical
resolution required to investigate local calcium flux in a variety of
physiological and pathological conditions.
Received 15 September 1994; accepted in final form 22 March 1995.
APS Manuscript Number R526-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.