Breathing pattern, CO2 elimination and the absence of exhaled NO in freely diving Weddell seals
| Autor: | O. Hoffmann, R. Mohnhaupt, J. Liggins, K.J. Falke, T. Busch, Warren M. Zapol, Jesse D. Roberts, K. S. Stanek, Graham C. Liggins |
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| Rok vydání: | 2008 |
| Předmět: |
Male
Pulmonary and Respiratory Medicine Time Factors Nitrogen Seals Earless Physiology Decompression Diving Biology Oxygen Consumption Functional residual capacity Tidal Volume medicine Animals Respiratory function Lung volumes Tidal volume Pulmonary Gas Exchange Respiration General Neuroscience Apnea Numerical Analysis Computer-Assisted Anatomy Carbon Dioxide Nitrogen washout Breathing medicine.symptom human activities |
| Zdroj: | Respiratory Physiology & Neurobiology. 162:85-92 |
| ISSN: | 1569-9048 |
| DOI: | 10.1016/j.resp.2008.04.007 |
| Popis: | Weddell seals undergo lung collapse during dives below 50 m depth. In order to explore the physiological mechanisms contributing to restoring lung volume and gas exchange after surfacing, we studied ventilatory parameters in three Weddell seals between dives from an isolated ice hole on McMurdo Sound, Antarctica. Methods Lung volumes and CO2 elimination were investigated using a pneumotachograph, infrared gas analysis, and nitrogen washout. Thoracic circumference was determined with a strain gauge. Exhaled nitric oxide was measured using chemiluminescence. Results Breathing of Weddell seals was characterized by an apneustic pattern with end-inspiratory pauses with functional residual capacity at the end of inspiration. Respiratory flow rate and tidal volume peaked within the first 3 min after surfacing. Lung volume reductions before and increases after diving were approximately 20% of the lung volume at rest. Thoracic circumference changed by less than 2% during diving. The excess CO2 eliminated after dives correlated closely with the duration of the preceding dive. Nitric oxide was not present in the expired gas. Conclusion Our data suggest that most of the changes in lung volume during diving result from compression and decompression of the gas remaining in the respiratory tract. Cranial shifts of the diaphragm and translocation of blood into the thorax rather than a reduction of thoracic circumference appear to compensate for lung collapse. The time to normalise gas exchange after surfacing was mainly determined by the accumulation of CO2 during the dive. These findings underline the remarkable adaptations of the Weddell seal for restoring lung volume and gas exchange after diving. |
| Databáze: | OpenAIRE |
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