Electrical membrane properties of rat substantia nigra compacta neurons in an in vitro slice preparation

T. Kita, Hitoshi Kita, S. T. Kitai

Research output: Contribution to journalArticle

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Abstract

The electrical membrane properties of rat substantia nigra pars compacta (SNC) neurons were studied in an in vitro slice preparation. Some of the recorded neurons were intracellularly labeled with HRP and were found to have morphological characteristics resembling the presumed SNC dopaminergic neurons, as reported by others. The input resistance of SNC neurons at resting membrane potential ranged between 70 and 250 MΩ. The membrane resistance showed strong anomalous rectification when the membrane was hyperpolarized by current injection. The anomalous rectification was decreased by the addition of tetraethylammonium bromide (TEA) to the bathing Ringer solution. Injection of depolarizing current or termination of hyperpolarizing current induced slow depolarizing potentials. Their amplitude was dependent on the membrane potential and the current intensity. In neurons treated with tetrodotoxin (TTX) and TEA, slow action potentials were triggered from the slow depolarizing potentials. Both the slow depolarizing potential and slow action potential were TTX resistant and abolished by superfusion of Ca2+-free medium. Long duration hyperpolarizations were observed following the injection of depolarizing current pulses. The hyperpolarization was abolished by the superfusion of Ca2+-free medium or decreased by addition of TEA to the Ringer solution indicating an involvement of a Ca2+-dependent K+-conductance in generation of the hyperpolarization. The long duration hyperpolarizationwas also observed following action potentials. The spike after hyperpolarization consisted of an initial short duration fast component and a long lasting component. The amplitude of both components seems to be reduced but not abolished by TEA (up to 10 mM). When hyperpolarizing current pulses were applied to neurons that were held either continuously depolarized or were superfused with Ca2+-free medium, the pattern of the membrane potential after the offset of current pulses consisted of an initial fast and a later slow ramp-shaped phase. The latter was associated with a membrane conductance increase and interpreted to be due to an early K+ current. This early K+ current was relatively resistant to TEA. Injections of strong depolarizing currents triggered action potentials with multiple inflections on their rising phase. The amplitudes of action potentials changed abruptly during current application. These data indicate that SNC neurons have multiple generation sites for action potential.

Original languageEnglish (US)
Pages (from-to)21-30
Number of pages10
JournalBrain Research
Volume372
Issue number1
DOIs
StatePublished - Apr 30 1986

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Tetraethylammonium
Action Potentials
Neurons
Membranes
Membrane Potentials
Injections
Tetrodotoxin
Architectural Accessibility
Dopaminergic Neurons
In Vitro Techniques
Pars Compacta

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

Cite this

Electrical membrane properties of rat substantia nigra compacta neurons in an in vitro slice preparation. / Kita, T.; Kita, Hitoshi; Kitai, S. T.

In: Brain Research, Vol. 372, No. 1, 30.04.1986, p. 21-30.

Research output: Contribution to journalArticle

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