Enhanced [3H]-noradrenaline release in synaptosomes from ethanol-tolerant animals: The role of nerve terminal calcium ion concentrations

Marina A. Lynch, John M. Littleton

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Cortical slices from brains of ethanol-tolerant rats have previously been shown to release a greater fraction of uptaken [3H]-noradrenaline ([3H]-NA) on K+ depolarisation than slices from control animals. In the present experiments, when stimulated with the Ca2+ ionophore A23187 (30 μM), untreated cortical synaptosomes release only a very small fraction of uptaken [3H]-NA. Under these conditions synaptosomal preparations from ethanol-tolerant animals released a greater fraction of uptaken [3H]-NA but the difference was not significant. However, after incubation with ouabain (100 μM, to increase intrasynaptosomal [Ca2+]) A23187 now produced a much greater enhancement of [3H]-NA release in preparations from ethanol-tolerant rats. Further, after superfusion of the synaptosomal preparation with 1mM EGTA and A23187 for 30 min (a procedure which should reduce intrasynaptosomal [Ca2+]) the reintroduction of Ca2+ to the superfusing fluid caused a marked release of [3H]-NA which was also significantly greater in preparations from ethanol-tolerant animals. Ca2+/Mg2+-ATPase activity was also higher in these synaptosomes but no difference could be detected in the release of [3H]-NA from a combined synaptic vesicle: synaptic plasma membrane preparation. The results suggest that the development of ethanol tolerance is associated with a fundamental change in the dynamic control of Ca2+ concentrations within the nerve terminal which potentiates the depolarisation-induced release of neurotransmitters.

Original languageEnglish
Pages (from-to)5-11
Number of pages7
JournalAlcohol and Alcoholism
Issue number1
StatePublished - 1985

Bibliographical note

Funding Information:
Acknowledgements — This work was supported with grants from the British Medical Research Council and the Medical Council on Alcoholism.

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Toxicology
  • Psychiatry and Mental health


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