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Halothane-induced intracellular calcium release in cholinergic cells.
R S Gomez1, C Guatimosim, J Barbosa
1Departamento de Cirurgia, Faculdade de Medicina da UFMG, Avenida Alfredo Balena, 190, CEP 30130-100,Belo Horizonte, Minas Gerais, Brazil. renatogomez@ig.com.br
Brain Research
|November 27, 2001
Summary
Sub-anesthetic concentrations of halothane increase intracellular calcium in cholinergic cells by releasing it from intracellular stores. This mechanism involves ryanodine-sensitive calcium channels and is independent of extracellular calcium.
Area of Science:
- Neuroscience
- Pharmacology
- Cell Biology
Background:
- Volatile anesthetics like halothane can influence neurotransmitter release.
- Previous studies indicated extracellular calcium-independent acetylcholine release by halothane and isoflurane.
Purpose of the Study:
- To investigate if halothane triggers calcium release from intracellular stores in cholinergic cells.
- To elucidate the specific intracellular calcium pathways involved in halothane's effects.
Main Methods:
- Utilized the SN56 cholinergic cell line.
- Measured intracellular calcium concentration ([Ca(2+)](i)) using fluo-3 dye and confocal microscopy.
- Administered halothane, ryanodine, dantrolene, and cyclopiazonic acid to assess calcium dynamics.
Main Results:
- Sub-anesthetic halothane concentrations increased [Ca(2+)](i) in SN56 cells, even without extracellular calcium.
- Halothane-induced calcium increase was attenuated by ryanodine and blocked by dantrolene, indicating involvement of ryanodine-sensitive stores.
- Inhibition of Ca(2+)-ATPase by cyclopiazonic acid reduced halothane's effect on [Ca(2+)](i).
Conclusions:
- Sub-anesthetic halothane concentrations stimulate calcium release from intracellular stores in cholinergic cells.
- The findings suggest a role for ryanodine-sensitive calcium channels in mediating halothane's effects on intracellular calcium.
- This intracellular calcium release mechanism may contribute to the overall neuropharmacological actions of halothane.