Tolerance of acute hypercapnic acidosis by the European eel ( Anguilla anguilla).

• Published in: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
• Main Authors: McKenzie, D J, Taylor, E W, Dalla Valle, A Z, Steffensen, J F
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2002
• Subjects: Anguilla anguilla
• Online Access: https://curis.ku.dk/portal/da/publications/tolerance-of-acute-hypercapnic-acidosis-by-the-european-eel--anguilla-anguilla(21fffbd0-8931-11dd-9c20-000ea68e967b).html; https://doi.org/10.1007/s00360-002-0260-5

Udgivelsesdato: 2002-May European eels ( Anguilla anguilla) were exposed sequentially to partial pressures of CO(2) in the water ( PwCO(2)) of 5, 10, 20, 40, 60 then 80 mm Hg (equivalent to 0.66-10.5 kPa), for 30 min at each level. This caused a profound drop in arterial plasma pH, from 7.9 to below 7.2, an increase in arterial PCO(2) from 3.0 mm Hg to 44 mm Hg, and a progressive decline in arterial blood O(2) content (caO(2)) from 10.0% to 1.97% volume. Gill ventilation rate increased significantly at water PwCO(2)s of 10, 20 and 40 mm Hg, followed by a decline at PwCO(2)s of 60 and 80 mm Hg, due to periodic breathing. Mean opercular pressure amplitude increased steadily throughout hypercapnic exposure and was significantly elevated at a PwCO(2) of 80 mm Hg. Hypercapnia caused a tachycardia between PwCO(2)s of 5 mmHg and 10 mm Hg, followed by a progressive decline in heart rate. Cardiac output (CO) remained unchanged throughout, as a consequence of a significant increase in stroke volume at PwCO(2)s of 40, 60 and 80 mm Hg. The eels maintained O(2) uptake at routine normocapnic levels throughout hypercapnic exposure. A comparison of the rates of blood O(2) delivery (calculated from CO and caO(2)) against O(2) consumption at PwCO(2)s of 60 mm Hg and 80 mm Hg indicated that a portion of O(2) uptake was due to cutaneous respiration. Thus, the European eel's exceptional tolerance of acute hypercapnia is probably a consequence of the tolerance of its heart to acidosis and hypoxia, and a contribution to O(2) uptake from cutaneous respiration.