title: Ventilation and phrenic output following high cervical spinal hemisection in male vs. female rats.
abstract: Female sex hormones influence the neural control of breathing and may impact neurologic recovery from spinal cord injury. We hypothesized that respiratory recovery after C2 spinal hemisection (C2HS) differs between males and females and is blunted by prior ovariectomy (OVX) in females. Inspiratory tidal volume (VT), frequency (fR), and ventilation (VE) were quantified during quiet breathing (baseline) and 7% CO2 challenge before and after C2HS in unanesthetized adult rats via plethysmography. Baseline breathing was similarly altered in all rats (reduced VT, elevated fR) but during hypercapnia females had relatively higher VT (i.e. compared to pre-injury) than male or OVX rats (p<0.05). Phrenic neurograms recorded in anesthetized rats indicated that normalized burst amplitude recorded ipsilateral to C2HS (i.e. the crossed phrenic phenomenon) is greater in females during respiratory challenge (p<0.05 vs. male and OVX). We conclude that sex differences in recovery of VT and phrenic output are present at 2 weeks post-C2HS. These differences are consistent with the hypothesis that ovarian sex hormones influence respiratory recovery after cervical spinal cord injury.
authors.affiliation: University of Florida, College of Public Health and Health Professions, Department of Physical Therapy, PO Box 100154, 100 Newell Drive, Gainesville, FL 32610, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Doperalski
authors.forename: M S
authors.initials: MS
authors.lastname: Sandhu
authors.forename: R W
authors.initials: RW
authors.lastname: Bavis
authors.forename: P J
authors.initials: PJ
authors.lastname: Reier
authors.forename: D D
authors.initials: DD
authors.lastname: Fuller
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002574:Cervical Vertebrae; D004958:Estradiol / Q000097:blood; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D008297:Male; D016555:Matched-Pair Analysis; D010791:Phrenic Nerve / Q000502:physiology* / Q000503:physiopathology; D010993:Plethysmography, Whole Body; D011374:Progesterone / Q000097:blood; D012123:Pulmonary Ventilation / Q000502:physiology*; D051381:Rats; D020127:Recovery of Function / Q000502:physiology*; D012120:Respiration Disorders / Q000150:complications* / Q000503:physiopathology; D012737:Sex Factors; D013119:Spinal Cord Injuries / Q000150:complications* / Q000503:physiopathology; D018709:Statistics, Nonparametric
chemical_list: D011374:Progesterone; D004958:Estradiol