Obesity is the most important predictor for obstructive sleep apnea. Although we know that obesity is assoc- iated with a decrease in pharyngeal airway size and an increase in pharyngeal airway collapsibility, we have almost no understanding of how obesity alters the mechanical properties of pharyngeal wall tissues to effect these changes. The PI has developed a novel application of MRI with tissue motion tracking (spatial modul- ation of magnetization, or SPAMM?) to examine the relationships between regional changes in pharyngeal airway size and pharyngeal wall tissue motion in anesthetized rats. Using this innovative technique, we will determine the effects of obesity on pharyngeal mechanics by studying three groups of Zucker rats with different degrees of body fat: lean, obese, and even more obese rats fed a high-fat diet. Our global hypo- thesis is that obesity compromises pharyngeal airway patency through airway narrowing, increased airway collapsibility, and less effective muscle mechanics.
Aim 1 is to determine 1) whether pharyngeal airway compliance and closing pressure progressively increase across age-matched Zucker rats in the order: lean
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