Related Experiment Videos
Ascorbate transport and intracellular concentration in cerebral astrocytes
1Department of Physiology, University of Western Ontario, London, Canada.
Journal of Neurochemistry
|July 1, 1995
Summary
Rat cerebral astrocytes accumulate vitamin C (ascorbate) via sodium-dependent transporters. Cyclic AMP signaling regulates both ascorbate uptake and efflux, controlling its concentration within these brain cells.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Ascorbate (vitamin C) is crucial for brain function, but its transport and regulation in astrocytes are not fully understood.
- Astrocytes play vital roles in maintaining the brain microenvironment, including regulating neurotransmitter and ion concentrations.
Purpose of the Study:
- To investigate the mechanisms regulating ascorbate uptake and intracellular concentration in rat cerebral astrocytes.
- To determine the role of sodium and specific inhibitors in ascorbate transport.
- To explore the effect of cyclic AMP on ascorbate transport pathways.
Main Methods:
- Incubation of rat cerebral astrocytes with radiolabeled ascorbate ([14C]-ascorbate).
- Measurement of ascorbate uptake rates and intracellular concentrations under varying conditions (e.g., Na+ dependence, sulfinpyrazone inhibition).
- Assessment of ascorbate efflux using digitonin permeabilization and comparison with a fluorescent marker.
- Treatment of astrocytes with dibutyryl cyclic AMP (dBcAMP) to evaluate its effects on ascorbate transport.
Main Results:
- Astrocytes accumulate millimolar concentrations of ascorbate from the medium, independent of synthesis.
- [14C]-ascorbate uptake and intracellular levels are dependent on extracellular Na+ and inhibited by sulfinpyrazone.
- Most intracellular ascorbate is localized to the cytosol.
- dBcAMP treatment significantly increased the rate of ascorbate uptake and steady-state intracellular concentration.
- dBcAMP also enhanced ascorbate efflux, explaining the modest net increase in intracellular ascorbate.
Conclusions:
- Rat cerebral astrocytes possess active transport mechanisms for ascorbate uptake, sensitive to Na+ and sulfinpyrazone.
- Cyclic AMP-dependent pathways regulate both ascorbate uptake and efflux in astrocytes.
- These regulatory mechanisms are crucial for controlling cytosolic ascorbate concentration within astrocytes, impacting brain homeostasis.