Sex Differences in Spontaneous Respiratory Recovery in Chronic Hemisection

Authors

Taylor C. Holmes, Marquette University
Nicole M. Popp, Marquette University
Carley F. Hintz, Marquette University
Isabell Dobrzycki, Marquette University
Carolyn J. Schmitz, Marquette University
Kaylyn A. Schwichtenberg, Marquette University
Elisa J. Gonzalez-Rothi, University of Florida - Gainesville
Christopher W. Sundberg, Marquette UniversityFollow
Kristi A. Streeter, Marquette UniversityFollow

Document Type

Article

Publication Date

7-2024

Publisher

American Physiological Society

Source Publication

Journal of Applied Physiology

Source ISSN

8750-7587

Original Item ID

DOI: 10.1152/japplphysiol.00040.2024

Abstract

Respiratory deficits after C2 hemisection (C2Hx) have been well documented through single-sex investigations. Although ovarian sex hormones enable enhanced respiratory recovery observed in females 2 wk post-C2Hx, it remains unknown if sex impacts spontaneous respiratory recovery at chronic time points. We conducted a longitudinal study to provide a comprehensive sex-based characterization of respiratory neuromuscular recovery for 8 wk after C2Hx. We recorded ventilation and chronic diaphragm electromyography (EMG) output in awake, behaving animals, phrenic motor output in anesthetized animals, and performed diaphragm muscle histology in chronically injured male and female rodents. Our results show that females expressed a greater recovery of tidal volume and minute ventilation compared with males during subacute and chronic time points. Eupneic diaphragm EMG amplitude during wakefulness and phrenic motor amplitude are similar between sexes at all time points after injury. Our data also suggest that females have a greater reduction in ipsilateral diaphragm EMG amplitude during spontaneous deep breaths (e.g., sighs) compared with males. Finally, we show evidence for atrophy and remodeling of the fast, fatigable fibers ipsilateral to injury in females, but not in males. To our knowledge, the data presented here represent the first study to report sex-dependent differences in spontaneous respiratory recovery and diaphragm muscle morphology following chronic C2Hx. These data highlight the need to study both sexes to inform evidence-based therapeutic interventions in respiratory recovery after spinal cord injury (SCI).

Comments

Journal of Applied Physiology, Vol. 137, No. 1 (July 2024): 166-180. DOI. © 2024 American Physiological Society. Used with permission.

Recommended Citation

Holmes, Taylor C.; Popp, Nicole M.; Hintz, Carley F.; Dobrzycki, Isabell; Schmitz, Carolyn J.; Schwichtenberg, Kaylyn A.; Gonzalez-Rothi, Elisa J.; Sundberg, Christopher W.; and Streeter, Kristi A., "Sex Differences in Spontaneous Respiratory Recovery in Chronic Hemisection" (2024). Physical Therapy Faculty Research and Publications. 226.
https://epublications.marquette.edu/phys_therapy_fac/226