Epithelial Na + sodium channels in magnocellular cells of the rat supraoptic and paraventricular nuclei

Ryoichi Teruyama, Mayumi Sakuraba, Lori L. Wilson, Narine E.J. Wandrey, William Armstrong

Research output: Contribution to journalArticle

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Abstract

The epithelial Na + channels (ENaCs) are present in kidney and contribute to Na + and water homeostasis. All three ENaC subunits (α, β, and γ) were demonstrated in the cardiovascular regulatory centers of the rat brain, including the magnocellular neurons (MNCs) in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN). However, the functional significance of ENaCs in vasopressin (VP) and oxytocin (OT) synthesizing MNCs is completely unknown. In this study, we show with immunocytochemical double-labeling that the α-ENaC is colocalized with either VP or OT in MNCs in the SON and PVN. In addition, parvocellular neurons in the dorsal, ventrolateral, and posterior subregions of the PVN (not immunoreactive to VP or OT) are also immunoreactive for α-ENaC. In contrast, immunoreactivity to β- and γ-ENaC is colocalized with VP alone within the MNCs. Furthermore, immunoreactivity for a known target for ENaC expression, the mineralcorticoid receptor (MR), is colocalized with both VP and OT in MNCs. Using single-cell RT-PCR, we detected mRNA for all three ENaC subunits and MR in cDNA libraries derived from single MNCs. In whole cell voltage clamp recordings, application of the ENaC blocker benzamil reversibly reduced a steady-state inward current and decreased cell membrane conductance approximately twofold. Finally, benzamil caused membrane hyperpolarization in a majority of VP and about one-half of OT neurons in both spontaneously firing and quiet cells. These results strongly suggest the presence of functional ENaCs that may affect the firing patterns of MNCs, which ultimately control the secretion of VP and OT.

Original languageEnglish (US)
Pages (from-to)273-285
Number of pages13
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume302
Issue number3
DOIs
StatePublished - Feb 1 2012

Fingerprint

Epithelial Sodium Channels
Supraoptic Nucleus
Paraventricular Hypothalamic Nucleus
Vasopressins
Oxytocin
Neurons
Gene Library
Homeostasis
Cell Membrane

All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

Cite this

Epithelial Na + sodium channels in magnocellular cells of the rat supraoptic and paraventricular nuclei. / Teruyama, Ryoichi; Sakuraba, Mayumi; Wilson, Lori L.; Wandrey, Narine E.J.; Armstrong, William.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 302, No. 3, 01.02.2012, p. 273-285.

Research output: Contribution to journalArticle

Teruyama, Ryoichi ; Sakuraba, Mayumi ; Wilson, Lori L. ; Wandrey, Narine E.J. ; Armstrong, William. / Epithelial Na + sodium channels in magnocellular cells of the rat supraoptic and paraventricular nuclei. In: American Journal of Physiology - Endocrinology and Metabolism. 2012 ; Vol. 302, No. 3. pp. 273-285.
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