Membrane properties of area postrema neurons

Meredith Hay, Kathy A. Lindsley

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Intrinsic membrane properties, voltage-dependent sodium and voltage-dependent potassium currents of area postrema neurons in culture have been characterized with respect to their voltage dependence, time dependence and sensitivity to specific blocking agents. The area postrema is a hindbrain circumventricular organ which is known to have an important role in the central regulation of cardiovascular function. This study is the first to describe the biophysical properties of ion channels present in rat area postrema neurons. Recordings in current-clamp mode revealed a mean resting membrane potential of -55.0 ± 1.6 (n = 24) mV and an input resistance of 213.6 ± 23 M Ω. For the 24 neurons tested, the evoked action potential had a mean threshold of 38.8 ± 2 mV and a mean amplitude of 107.3 ± 15 mV. Our results show that the area postrema possesses only one principle sodium current which is completely abolished by 5 μM tetrodotoxin (TTX) (n = 28). This current activated near -50 mV and reached peak amplitude at -30 mV. The area postrema does not possess a TTX insensitive sodium current. The area postrema has at least two types of potassium currents. All area postrema neurons studied with tetraethylamonium (TEA) (n = 40) showed the presence of a slowly activating outward current which was present at voltages greater than -40 mV and was blocked by 10 mM TEA. In addition, 75% of the neurons studied (n = 30/40) also showed a rapidly inactivating, 4-AP sensitive IA type current which activated near -30 mV. Angiotensin II attenuated both the peak and the steady-state potassium currents, suggesting that angiotensin 11 may modulate area postrema activity by inhibiting voltage-gated potassium channels.

Original languageEnglish (US)
Pages (from-to)199-208
Number of pages10
JournalBrain Research
Volume705
Issue number1-2
DOIs
StatePublished - Dec 24 1995
Externally publishedYes

Keywords

  • Angiotensin II
  • Area postrema
  • Circumventricular organ
  • Potassium channel
  • Sodium channel

ASJC Scopus subject areas

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

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