Calcium Compartments in Brain

Journal Article · Tue Jan 01 04:00:00 EST 2002 · Journal of Cerebral Blood Flow and Metabolism

DOI:https://doi.org/10.1097/00004647-200204000-00012· OSTI ID:980048

Newman, G; Hospod, F; Patlak, C; Trowbridge, S; Wilke, R; Fuhrmann, M; Jones, K

Excellent progress has been made toward understanding the physiology and pharmacology of specific calcium-related cellular processes of the brain, but few studies have provided an integrated view of brain calcium kinetics. To further the knowledge of the size and binding properties of brain calcium compartments, the authors have conducted a series of experiments in hippocampal brain slices exposed to high and low extracellular calcium. Slices were incubated in buffers containing 0.001 to 4.5 mmol/L calcium for up to 75 minutes. Slice calcium content was analyzed by three methods: exchange equilibrium with {sup 45}Ca, synchrotron-radiation-induced x-ray emission, and inductively coupled plasma. Data were analyzed using a model based on a Langmuir isotherm for two independent sites, with additional extracellular and bound compartments. In parallel experiments, altered low calcium had no effect on slice histology and only mild effects on slice adenylates. When combined with prior {sup 45}Ca and fluorescent probe binding experiments, these results suggest that there are at least five kinetically distinct calcium compartments: (1) free extracellular (10%); (2) loosely associated extracellular plasma membrane (55%); (3) intracellular compartment with moderate avidity (17%); (4) tightly bound, nonexchangeable intracellular compartment (15%); and (5) free cytoplasmic (<0.01%). If only the third compartment is considered a potential calcium buffer, then the buffering ratio is calculated to be 2,700:1, but if the second compartment is also included, then the buffering ratio would be 13,000:1. This may explain the wide range of estimates observed by fluorescent probe studies.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 980048
• Report Number(s): BNL--92966-2010-JA
• Journal Information: Journal of Cerebral Blood Flow and Metabolism, Journal Name: Journal of Cerebral Blood Flow and Metabolism Vol. 22; ISSN JCBMDN; ISSN 0271-678X
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
BRAIN
BUFFERS
CALCIUM
COMPARTMENTS
DATA
EMISSION
EQUILIBRIUM
HISTOLOGY
ISOTHERMS
KINETICS
MEMBRANES
PHARMACOLOGY
PHYSIOLOGY
PLASMA
POTENTIALS
RANGE
SIZE
national synchrotron light source