title: Determination of local rates of 45Ca influx into rat brain by quantitative autoradiography: studies of aging.
abstract: 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.
authors.affiliation: Laboratory of Cerebral Metabolism, National Institute of Mental Health, Bethesda, Maryland 20892, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Dienel
authors.forename: B
authors.initials: B
authors.lastname: Tofel-Grehl
authors.forename: C C
authors.initials: CC
authors.lastname: Cruz
authors.forename: K
authors.initials: K
authors.lastname: Luludis
authors.forename: K
authors.initials: K
authors.lastname: Pettigrew
authors.forename: L
authors.initials: L
authors.lastname: Sokoloff
authors.forename: G E
authors.initials: GE
authors.lastname: Gibson
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D001692:Biological Transport; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000097:blood / Q000493:pharmacokinetics*; D002132:Calcium Radioisotopes; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D002132:Calcium Radioisotopes; D002118:Calcium