Determination of local rates of 45Ca influx into rat brain by quantitative autoradiography: studies of aging
Dienel, G.A.; Tofel-Grehl, B.; Cruz, C.C.; Luludis, K.; Pettigrew, K.; Sokoloff, L.; Gibson, G.E.
American Journal of Physiology 269(2 Pt 2): R453-R462
1995
ISSN/ISBN: 0002-9513 PMID: 7653670 Document Number: 441432
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 with results obtained with a quantitative autoradiographic procedure developed to assay influx of 45Ca into brain. Regional calcium contents, brain-to-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- to 14-fold, and rates of movement of 45Ca down concentrations gradients varied by a factor of 7. 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.