Inhibitory Effects of Norepinephrine on the Potassium Current of Rat Medial Vestibular Nuclear Neurons

ABSTRACT

BACKGROUND: This study aimed to explore the effects of norepinephrine on the potassium currents of rat medial vestibular nuclear neurons by using the whole-cell patch clamp technique. METHODS: Sprague-Dawley rats aged 14 to 16 days were anesthetized with ether and decapitated. After enzymatic digestion, the portion of the medial vestibular nucleus neurons were obtained by micropunching. The dissociated neurons were transferred into a recording chamber mounted on an inverted microscope and potassium currents were recorded by standard patch-clamp techniques under voltage-clamp modes. RESULTS: Norepinephrine inhibited the whole potassium currents of the medial vestibular nuclear neurons. Outward potassium currents were more suppressed in 4 mM 4-aminopyridine and norepinephrine added solutions than 4 mM 4-aminopyridine only, but were not suppressed in 10 mM tetraethylammonium and norepinephrine added solutions compared to 10 mM tetraethylammonium only. CONCLUSIONS: These results suggest that norepinephrine blocks the delayed rectifier potassium channels in medial vestibular nuclear neurons.