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Caffeine-sensitive calcium stores in presynaptic nerve endings: a physiological role?
A Martínez-Serrano1, J Satrústegui
1Departamento de Biología Molecular, Universidad Autónoma de Madrid, Spain.
Biochemical and Biophysical Research Communications
|June 30, 1989
Summary
Researchers investigated calcium homeostasis in rat brain synaptosomes. They found that caffeine-sensitive internal calcium stores help buffer calcium loads from plasma membrane depolarization.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Calcium homeostasis is crucial for neuronal function.
- Synaptosomes are vital for studying neurotransmitter release and calcium dynamics.
- Understanding intracellular calcium stores is key to neuronal signaling.
Purpose of the Study:
- To investigate calcium homeostasis in rat brain synaptosomes.
- To identify and characterize intracellular calcium stores.
- To determine the role of these stores in buffering calcium influx.
Main Methods:
- Utilized Ca2+-sensitive minielectrodes for calcium measurements.
- Employed fluorescent cytosolic calcium probes (quin2 and fura2).
- Studied both intact and permeabilized synaptosomes from rat brain.
Main Results:
- Identified a vesicular, non-mitochondrial, ATP-dependent calcium uptake system in permeabilized synaptosomes.
- This system showed vanadate sensitivity, similar to endoplasmic reticulum-type organelles.
- Caffeine was demonstrated to mobilize calcium from these internal stores in intact synaptosomes.
Conclusions:
- Caffeine-sensitive calcium stores play a significant role in buffering calcium loads.
- These stores are involved in managing calcium influx following plasma membrane depolarization.
- The findings contribute to understanding calcium regulation in neuronal function.