Elsevier

Neuroscience

Volume 13, Issue 1, September 1984, Pages 137-156
Neuroscience

Membrane properties of rat locus coeruleus neurones

https://doi.org/10.1016/0306-4522(84)90265-3Get rights and content

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.

Reference (40)

  • GuyenetP.G. et al.

    Excitation of neurons in the nucleus locus coeruleus by substance P and related peptides

    Brain Res.

    (1977)
  • HalliwellJ.V. et al.

    Voltage-clamp analysis of muscarinic excitation in hippocampal neurons

    Brain Res.

    (1982)
  • KorfJ. et al.

    Noradrenergic neurons: morphine inhibition of spontaneous activity

    Eur. J. Pharmac.

    (1974)
  • SwansonL.W.

    The locus coeruleus: a cytoarchitectonic, Golgi and immunohistochemical study in the albino rat

    Brain Res.

    (1976)
  • AghajanianG.K. et al.

    α2-Adrenoceptor-mediated hyperpolarization of locus coeruleus neurons: intracellular studies in vivo

    Science N.Y.

    (1982)
  • AndradeR. et al.

    Locus coeruleus activity in vitro: intrinsic regulation by a calcium-dependent potassium conductance but not α2-adrenoceptors

    J. Neurosci.

    (1984)
  • Aston-JonesG. et al.

    Activity of norepinephrine-containing locus coeruleus neurons in behaving rats anticipates fluctuations in the sleep-waking cycle

    J. Neurosci.

    (1981)
  • Aston-JonesG. et al.

    Norepinephrine-containing locus coeruleus neurons in behaving rats exhibit pronounced responses to non-noxious environmental stimuli

    J. Neurosci.

    (1981)
  • BrownD.A. et al.

    Calcium-dependence of a component of transient outward current in bullfrog ganglion cells

    Soc. Neurosci. Abstr.

    (1982)
  • BrownD.A. et al.

    Persistent slow inward calcium current in voltage-clamped hippocampal neurones of the guinea-pig

    J. Physiol., Lond.

    (1983)
  • Cited by (0)

    View full text