Membrane properties and the excitatory junction potentials in smooth muscle cells of cochlear spiral modiolar artery in guinea pigs

Zhi Gen Jiang, Jianhua Qiu, Tianying Ren, Alfred L. Nuttall

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Blood circulation changes in the inner ear play an important role in many physiological and pathological conditions of hearing function. The spiral modiolar artery (SMA) is the terminal artery to the cochlea. It was surrounded with nerve fibers immunostained by an antibody for tyrosine hydroxylase. By using intracellular recording techniques on the acutely isolated SMA, membrane properties of the smooth muscle cells and the neuromuscular transmission in this preparation were investigated. With minimum tension and normal extracellular K+ concentration (5 mM), the majority of muscle cells showed a resting potential near -80 mV and an input resistance of about 8 MΩ. V/I plot showed an inward rectification in these cells. Barium (50-500 μM) caused strong depolarization and an increase in input resistance. Transmural electrical stimulation evoked stimulation intensity-dependent depolarizations (2-31 mV) following a short latency (~20 ms). The evoked potential by a low intensity stimulus was completely blocked by 1 μM tetrodotoxin. The potential and a depolarization induced by norepinephrine (10 μM) was usually partially (40-90%) blocked by α-receptor antagonists prazosin and/or idazoxan with concentrations up to 1 μM. Action potentials were observed when the depolarization was more than -40 mV. It is concluded that SMA smooth muscle cells, similar to those in other brain small arteries, highly express inward rectifying potassium channels; the cells receive catecholaminergic innervation, and stimulation of the nerves elicited an excitatory junction potential that is partially mediated by adrenergic receptors.

Original languageEnglish (US)
Pages (from-to)171-180
Number of pages10
JournalHearing Research
Volume138
Issue number1-2
DOIs
StatePublished - Dec 1 1999

Keywords

  • Cochlea
  • Excitatory junction potential
  • Membrane potential
  • Smooth muscle cells
  • Spiral modiolar artery
  • α-receptor

ASJC Scopus subject areas

  • Sensory Systems

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