Membrane properties of rat locus coeruleus neurones

John Williams, R. A. North, S. A. Shefner, S. Nishi, T. M. Egan

Research output: Contribution to journalArticle

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Abstract

Intracellular recordings were made from neurones in the locus coeruleus contained within a slice cut from rat pons and maintained in vitro. Most neurones fired action potentials spontaneously at frequencies of between 1 and 5 Hz; this did not arise from spontaneous synaptic input but appeared to result from endogenous properties of the membrane conductances. Under voltage clamp at potentials near threshold for action potential generation (- 55 mV) there was a persistent inward calcium current. This current became less with membrane hyperpolarization and was abolished at about -70 mV. Two potassium currents were observed. The first had properties similar to that generally described as the "fast" potassium current (IK,A); it flowed transiently (for about 200 ms) when the membrane potential passed from about -65 to -45 mV, and was blocked by 4-aminopyridine. The second was a calcium-activated potassium current (IK,Ca); it flowed for several seconds following a burst of calcium action potentials. Spontaneous and evoked action potentials had both tetrodotoxin-sensitive and tetrodotoxin-resistant components. The latter was apparently due to calcium entry. The potential changes occurring during the spontaneous firing of locus coeruleus neurones could be reconstructed qualitatively from the ionic conductances observed. The membrane properties of the locus coeruleus neurones were remarkably uniform; however, about 5% of cells impaled within the region of the locus coeruleus were electrophysiologically distinct. These atypical cells had short duration action potentials, did not fire spontaneously and had large spontaneous depolarizing synaptic potentials.

Original languageEnglish (US)
Pages (from-to)137-156
Number of pages20
JournalNeuroscience
Volume13
Issue number1
DOIs
StatePublished - 1984
Externally publishedYes

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Locus Coeruleus
Action Potentials
Neurons
Membranes
Calcium
Potassium
Tetrodotoxin
4-Aminopyridine
Synaptic Potentials
Pons
Evoked Potentials
Membrane Potentials

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Williams, J., North, R. A., Shefner, S. A., Nishi, S., & Egan, T. M. (1984). Membrane properties of rat locus coeruleus neurones. Neuroscience, 13(1), 137-156. https://doi.org/10.1016/0306-4522(84)90265-3

Membrane properties of rat locus coeruleus neurones. / Williams, John; North, R. A.; Shefner, S. A.; Nishi, S.; Egan, T. M.

In: Neuroscience, Vol. 13, No. 1, 1984, p. 137-156.

Research output: Contribution to journalArticle

Williams, J, North, RA, Shefner, SA, Nishi, S & Egan, TM 1984, 'Membrane properties of rat locus coeruleus neurones', Neuroscience, vol. 13, no. 1, pp. 137-156. https://doi.org/10.1016/0306-4522(84)90265-3
Williams, John ; North, R. A. ; Shefner, S. A. ; Nishi, S. ; Egan, T. M. / Membrane properties of rat locus coeruleus neurones. In: Neuroscience. 1984 ; Vol. 13, No. 1. pp. 137-156.
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