Submitted on September 5, 2008
Revised on January 5, 2009
Accepted on January 22, 2009
Laryngeal Constriction During Hypoxic Gasping and its Role in Improving Autoresuscitation in Two Mouse Strains
Zheng Song1, Kathleen A. Harris1, and Bradley T. Thach2*
1 Washington University School of Medicine
2 Washington University School of Medecine
* To whom correspondence should be addressed. E-mail: Thach{at}KIDS.WUSTL.EDU.
Laryngeal closure following hypoxic gasps has been documented but its efficacy in improving autoresuscitation capacity is unknown. We studied SWR/J mice who normally cannot autoresuscitate and the C57/BLJ strain who can. We evaluated the effects of elevated end inspiratory lung volume immediately following a gasp. We compared upper airway intact mice with tracheostomized mice in which the vocal cords are bypassed. We used the techniques of repeated autoresuscitate trials to test autoresuscitation capability. Both SWR/J and C57/BLJ mice could maintain elevated lung volume immediately after a gasp (breath holding). Such breath holding increased autoresuscitation ability in C57/BLJ mice but did not in SWR/J mice. In SWR/J mice the duration of the breath holds was less than that in the C57/BLJ mice. These findings indicate that gasp associated breath holding improves autoresuscitation capability during repeated autoresuscitation trials. Also, they show that SWR/J mice have a deficiency in CNS mechanisms regulating glottic closure during hypoxic gasping.
