Distribution of calcium and potassium in presynaptic nerve terminals from cerebellar cortex.
- 1 March 1987
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 84 (6), 1713-1717
- https://doi.org/10.1073/pnas.84.6.1713
Abstract
The elemental composition of the presynaptic nerve terminals in rapidly frozen synapses of the cerebellar molecular layer was determined by electron probe x-ray microanalysis and elemental imaging of characteristic x-rays. Elemental imaging of thin freeze-dried cryosections from fresh cerebellar slices frozen within 20 sec of removal from the brain showed normal concentrations of potassium (95 .+-. 6 mmol/liter wet tissue .+-. SEM) and calcium (0.8 .+-. 0.4 mmol/liter) in whole presynaptic terminals, even though mitochondrial and nonmitochondrial sites containing up to 30 mmol of calcium per liter were present elsewhere in the neuropil. Quantitative electron probe analysis of synaptic vesicle clusters and intraterminal mitochondria indicated that their calcium concentrations were 0.4 .+-. 0.1 and 1.2 .+-. 0.2 mmol/liter, respectively. The low calcium content of presynaptic organelles was confirmed by the absence of detectable deposits in preparations freeze-substituted so as to stabilize calcium content. Similar experiments were carried out on cerebellar slices rapidly frozen after incubation in vitro. The distribution of potassium and calcium in presynaptic terminals of resting and depolarized (55 mM potassium) slices was qualitatively and quantitatively similar to that in freshly excised cortex, although resting slices lacked the few calcium-rich sites that appeared in other areas of the neuropil after stimulation. The calcium concentrations in whole terminals, synaptic vesicles, and mitochondria of resting slices were 1.4 .+-. 0.7, 0.7 .+-. 0.2, and 0.9 .+-. 0.2 mmol/liter, respectively. Thus, amounts of calcium typical of storage organelles in other tissues are not present within cerebellar synaptic vesicles, suggesting that they a limited role in calcium storage and release.This publication has 27 references indexed in Scilit:
- Cell physiology: Cellular site of calcium regulationNature, 1984
- Role for microsomal Ca storage in mammalian neurones?Nature, 1984
- Cytoplasmic organization in cerebellar dendritic spines.The Journal of cell biology, 1983
- The distribution of intracellular ions in the avian salt gland.The Journal of cell biology, 1983
- ATP‐Stimulated Ca2+ Transport into Cholinergic Torpedo Synaptic VesiclesJournal of Neurochemistry, 1980
- ATP-Dependent calcium uptake by cholinergic synaptic vesicles isolated fromtorpedo electric organThe Journal of Membrane Biology, 1980
- Synaptic vesicle exocytosis captured by quick freezing and correlated with quantal transmitter release.The Journal of cell biology, 1979
- Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sectionsThe Journal of cell biology, 1977
- Calcium and pancreatic secretion. I. Subcellular distribution of calcium and magnesium in the exocrine pancreas of the guinea pig.The Journal of cell biology, 1975
- CALCIUM METABOLISM IN ISOLATED BRAIN CELLS AND SUBCELLULAR FRACTIONSJournal of Neurochemistry, 1974