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Ethanol and synaptosomal calcium homeostasis.
M Davidson1, P Wilce, B Shanley
1Department of Biochemistry, University of Queensland, St Lucia, Australia.
Biochemical Pharmacology
|April 15, 1990
Summary
Ethanol disrupts calcium homeostasis in rat synaptosomes, increasing intracellular calcium levels. This effect appears to involve the endoplasmic reticulum, not ion channels or sodium-calcium exchange.
Area of Science:
- Neuroscience
- Neurochemistry
- Cellular Physiology
Background:
- Synaptosomes are crucial for neurotransmission and rely on precise calcium regulation.
- Ethanol's neurotoxic effects are partly attributed to its impact on cellular calcium homeostasis.
- Understanding ethanol's mechanism on synaptosomal calcium is vital for neurodegenerative disease research.
Purpose of the Study:
- To investigate the specific effects of ethanol on synaptosomal calcium homeostasis in rats.
- To elucidate the cellular mechanisms underlying ethanol-induced alterations in intracellular calcium.
Main Methods:
- Utilized rat synaptosomes for ex vivo experimentation.
- Employed the fluorescent dye fura-2 to measure intracellular free Ca2+ concentration ([Ca2+]i).
- Quantified 45Ca uptake to assess calcium influx and efflux dynamics.
Main Results:
- Ethanol significantly enhanced the rise in [Ca2+]i induced by the mitochondrial poison cyanide.
- Ethanol also augmented [Ca2+]i increases caused by ouabain, ruling out Na(+)-Ca2+ exchange as the primary mechanism.
- Calcium channel blockers (verapamil, La3+) did not inhibit ethanol's effect on [Ca2+]i.
- Caffeine preincubation reduced ethanol-induced [Ca2+]i rises, implicating the endoplasmic reticulum.
Conclusions:
- Ethanol profoundly impacts synaptosomal calcium homeostasis, leading to elevated intracellular calcium.
- The observed effects suggest ethanol interferes with calcium regulation at the endoplasmic reticulum level.
- Findings provide novel insights into ethanol's neurotoxicity and potential therapeutic targets.