Effects of aerial hypoxia and temperature on pulmonary breathing pattern and gas exchange in the South American lungfish, Lepidosiren paradoxa

摘要: The South American lungfish Lepidosiren paradoxa is an obligatory air-breathing fish possessing well-developed bilateral lungs, and undergoing seasonal changes in its habitat, including temperature changes. In the present study we aimed to evaluate gas exchange pulmonary breathing pattern L. at different temperatures (25 30°C) inspired O2 levels (21, 12, 10, 7%). Normoxic consisted of isolated ventilatory cycles composed expiration followed by 2.4±0.2 buccal inspirations. Both expiratory inspiratory tidal volumes reached a maximum about 35mlkg-1, indicating that able nearly all lung air single cycle. At both temperatures, hypoxia caused significant increase ventilation (VE), mainly due respiratory frequency. Durations cycle were not significantly affected hypoxia. Expiratory time (but inspiratory) was shorter 30°C levels. While small change oxygen consumption (VO2) could be noticed, carbon dioxide release (VCO2, P=0.0003) convection requirement (VE/VO2, P=0.0001) (7% O2) when compared normoxia, diffusion capacity increased four-fold hypoxic exposure. These data highlight important features system paradoxa, capable matching demand supply under environmental change, as well help understand evolution lungfish.