Abstract
The relationship between the mechanical properties of tracheal mucus and its rate of transport on the mucus-depleted frog palate was investigated. Mucus samples were obtained from dogs subject to a variety of physiological interventions - barbiturate anesthesia, tranquilization, cholinergic stimulation, and dehydration. For each sample, the elastic modulus, G′, and the dynamic viscosity, η′, were determined over the frequency range of 1 to 100 rad/sec by means of the magnetic rheometer technique, and the relative frog palate transport rate, Tr, was determined by previously described methods. For 102 control or near-control tracheal mucus samples, correlations were found relating the relative transport rate to either the elastic modulus or the viscosity, and, in addition, to the loss tangent, tan δ. At constant tan δ, Tr vs. log G′ or log η′ (determined at 1 rad/sec) gave partial correlation coefficients of −0.59; at constant G′, the partial correlation coefficient for Tr vs. tan δ was −0.45. Cholinergic stimulation and barbiturate anesthesia both induced rapid, gross changes in the tracheal mucus. With these acute interventions, the dependence of mucociliary transport on mucus mechanical properties was qualitatively similar to that seen in the chronic studies. The statistical variability was smaller, however, because the variation due to frog palate mucus was eliminated.
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