Related Experiment Videos
Calcium buffering and free Ca2+ in rat brain synaptosomes
1Department of Physiology, University of Maryland School of Medicine, Baltimore 21201.
Journal of Neurochemistry
|March 1, 1993
Summary
Presynaptic nerve terminals rapidly buffer incoming calcium ions. This buffering is crucial for regulating intracellular calcium levels during neuronal activity.
Area of Science:
- Neuroscience
- Cellular Biology
- Biochemistry
Background:
- Neuronal activity relies on precise regulation of intracellular calcium.
- Presynaptic terminals are key sites for neurotransmitter release, modulated by calcium dynamics.
Purpose of the Study:
- To investigate the rapid buffering and sequestration of calcium in rat brain presynaptic nerve terminals.
- To quantify the relationship between calcium influx and cytosolic calcium concentration changes.
Main Methods:
- Isolated rat brain presynaptic nerve terminals (synaptosomes) were used.
- Calcium influx was measured using the tracer 45Ca.
- Cytosolic free calcium ([Ca2+]cyt) was determined using fura-2 fluorescence.
Main Results:
- K+ depolarization and veratridine stimulation rapidly increased both 45Ca uptake and [Ca2+]cyt.
- The majority of entering calcium (up to 99.97%) was buffered or sequestered within seconds.
- A high calcium buffer ratio (beta) of approximately 3,500:1 was observed, indicating efficient intracellular calcium handling.
Conclusions:
- Rat brain presynaptic terminals possess highly effective mechanisms for buffering and sequestering calcium.
- Rapid calcium buffering is essential for maintaining low cytosolic calcium levels during neuronal stimulation.