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Glass, M.L., A. Ishimatsu, and K. Johansen, 1985. Responses of Aerial Ventilation to Hypoxia and Hypercapnia in Channa argus, an Air-Breathing Fish, University of Aarhus. Reprinted from Journal of Comparative Physiology B (1985) 156(3): 425-430 with kind permission from Springer Science and Business Media Responses of Aerial Ventilation to Hypoxia and Hypercapnia in Channa argus, an Air-Breathing FishVentilation of the air-breathing organ and aerial gas exchange were measured in 1 to 2 kg specimens at 15 and 25°C. Additionally, the ventilatory responses to hypoxia and hypercapnia were studied. Aerial ventilation increased from 1.1 to 2.9 ml·kg–1·min–1 when temperature rose from 15 to 25°C. Concomitantly, O2-uptake through airbreathing increased from 0.1 ml·kg–1·min–1 (15°C) to 0.28 ml·kg–1·min–1 (25°C), whereas aerial gas exchange was less important for CO2-climination as evident from low gas exchange ratios (0.16 at 15°C, 0.29 at 25°C). Ventilation increases only slightly in response to inspiration of hypercapnic gas mixtures or to hypoxic conditions in water. By contrast, inspiration of hypoxic gas mixtures caused marked increases of ventilation in particular at the higher temperature. Aerial ventilation inChanna is low compared to values for ectothermic pulmonary breathers. However, its ventilatory responses to hypoxia strikingly resemble those of reptiles: The most marked ventilatory response to hypoxia occurs at the higher temperature where the demands for O2 are greatest. Contact: Mogens Glass, Department of Zoophysiology, University of Aarhus,
DK-8000 Aarhus C, Denmark
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