Strain differences in pulmonary function of laboratory rats.

The effect of strain differences on pulmonary function was studied with male Sprague-Dawley and Fischer-344 rats. The larger Sprague-Dawley rats had a larger thoracic gas volume and specific thoracic gas volume (thoracic gas volume normalized for body mass) than the Fischer-344 rats. The thoracic gas volume differences corresponded to differences in static lung compliance reported in the literature for these strains of rats. The resistance of airways was less in the Sprague-Dawley rats but the specific conductance was greater in the Fischer-344 rats. These results suggested that even though the smaller Fischer-344 rats had a smaller lung volume and smaller cross sectional area of the airways, the caliber of the airways relative to lung volume was larger than that of the Sprague-Dawley rats.