# Ion Channel Mechanisms of Inspiratory Breathing Movements in Mice

> **NIH NIH R01** · COLLEGE OF WILLIAM AND MARY · 2020 · $309,516

## Abstract

PROJECT SUMMARY
Our goal is to explain the neurophysiology of breathing. Breathing refers to periodic movements of the chest
and airways that ventilate the lungs. To breathe, the brain must:
  Generate a rhythm,
  Produce a spatiotemporal pattern for breathing muscles,
  Integrate sensory feedback.
Here we focus on jobs 1 and 2, discovering the ionic mechanisms underlying the rhythm and motor pattern.
The brainstem preBötzinger complex (preBötC) generates the inspiratory breathing rhythm. Its core
rhythmogenic interneurons are derived from Dbx1-expressing progenitors (i.e., Dbx1 neurons). Because we
know the site (preBötC) and the canonical cell-class (Dbx1) at the point of origin for breathing, we are well
equipped to discover which ion channels influence normal inspiration (eupnea), ‘sighs’, and gasps in hypoxia.
We manipulate ion channels using genetic technologies. We assess breathing phenotypes in intact adult mice.
We explain the biophysics of these phenotypes via patch-clamp recordings from adult Dbx1 preBötC neurons.
Three types of ion channels are implicated in preBötC function: (1) Na+ channels that engender persistent Na+
current (INaP), (2) Transient receptor potential (Trp) channels that mediate Ca2+-activated nonspecific cationic
current (ICAN), and (3) K+ channels that give rise to transient outward K+ current (i.e., A-current, IA).
Specific aim 1 evaluates the role of INaP in Dbx1 preBötC neurons. A rhythmogenic role for INaP has been
suspected for 27 years. We use intersectional mouse genetics and short-hairpin RNA (shRNA) to knockout or
knock-down Na+ channel genes that give rise to INaP and evaluate its role in eupnea, sighing, and gasping.
Specific aim 2 evaluates the role of ICAN in Dbx1 preBötC neurons. ICAN is a major charge carrier for inspiratory
bursts. Next-generation RNA Seq technology provides us with a suite of Trp channel targets that we will
acutely attenuate using shRNA to test the role of ICAN in eupnea, sighing, and gasping.
Specific aim 3 evaluates the role of IA in Dbx1 preBötC neurons. IA-expressing preBötC neurons feature other
key rhythmogenic properties so they may be specialized. We use intersectional mouse genetics and shRNA to
knockout or knock-down K+ channel genes for IA to evaluate its role in eupnea, sighing, and gasping. Then we
selectively kill the 56% of IA-expressing Dbx1 preBötC neurons to test whether they serve a specialized
rhythmogenic role.
The success of this project would be a watershed in terms of understanding the ion channel-level origins of
real behavior. The new knowledge could be applicable to treatment and prophylaxis of respiratory pathologies
with a central etiology. The new knowledge may provide general insights regarding the neural origins of motor
rhythms.

## Key facts

- **NIH application ID:** 9894868
- **Project number:** 5R01NS107296-02
- **Recipient organization:** COLLEGE OF WILLIAM AND MARY
- **Principal Investigator:** Christopher A. Del Negro
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $309,516
- **Award type:** 5
- **Project period:** 2019-03-15 → 2023-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9894868

## Citation

> US National Institutes of Health, RePORTER application 9894868, Ion Channel Mechanisms of Inspiratory Breathing Movements in Mice (5R01NS107296-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9894868. Licensed CC0.

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