Pulmonary compliance and lung volume varies with ecomorphology in anuran amphibians: implications for ventilatory-assisted lymph flux

Abstract

). Lymph flux rates were also highest for R. marina, lowest for X. laevis and intermediate in L. catesbeianus. Thus, there is a strong correlation between pulmonary compliance, lung volume and lymph flux rates, which suggests that lymph mobilization capacity may explain some of the variation in pulmonary compliance and lung volume in anurans.

Pulmonary Compliance and Lung Volume Are Related to Terrestriality in Anuran Amphibians

“…Following lymph volume measurement and while anesthetized (as above), the amphibians were cranially pithed and then decapitated for measurements of pulmonary compliance (C p Dvolume/Dpressure; mL cm H 2 O Ϫ1 ) and lung volume (V lung ; mL), as detailed in Hedrick et al (2011). In brief, we measured mean pulmonary compliance (C) using a flared tracheal catheter fashioned from polyethylene tubing of appropriate size for the species, which was inserted through the glottis and anchored and sealed in place with sutures (4-0 silk) and cyanoacrylate adhesive.…”

“…Our findings suggest that invasion of terrestrial habitats by anurans provides a strong selection pressure for pulmonary characteristics, such as volume and compliance. Moreover, these pulmonary characteristics are not correlated with maximal metabolic rate for bufonids, ranids, and pipids (from Gatten et al 1992); hence, they appear to be unrelated to gas exchange per se (see also Hedrick et al 2011).…”

“…In a limited test with three species, the ability to mobilize lymph was found to be correlated with maximal pulmonary compliance and the degree of development of these skeletal muscles and to be compromised by lung filling and interference with muscle contraction (Hillman et al 2010bHedrick et al 2011). More compliant lungs allow great expansion volumes, which will move lymph more effectively from the body core to the axillary regions as well as create a larger pressure change in the subvertebral sac to move lymph from the axillary regions dorsally to the lymph hearts.…”

“…More compliant lungs allow great expansion volumes, which will move lymph more effectively from the body core to the axillary regions as well as create a larger pressure change in the subvertebral sac to move lymph from the axillary regions dorsally to the lymph hearts. Hedrick et al (2011) reported positive correlations between lung compliance and lung volume with the degree of terrestriality at the family level, with Bufonidae 1 Ranidae 1 Pipidae, but it is not clear whether lung compliance and lung volume vary in a broader spectrum of species with different degrees of terrestriality.…”

“…Previous studies have focused on the role of the femoral sac in lymph return because of its relative ease of study and its important role in lymphatic return from the hind limbs (e.g., Hillman et al 2004Hillman et al , 2005Hillman et al , 2011Drewes et al 2007Drewes et al , 2013Hedrick et al 2013). The femoral is a key ventral sac for the return of lymph to the circulatory system.…”