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The effect of sustained hypoxia on the cardio‐respiratory response of bowfin Amia calva : implications for changes in the oxygen transport system
Author(s) -
Porteus C. S.,
Wright P. A.,
Milsom W. K.
Publication year - 2014
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.12186
Subject(s) - hypoxia (environmental) , biology , acclimatization , oxygen , facultative , respiratory system , ecology , anatomy , chemistry , organic chemistry
This study examined mechanisms underlying cardio‐respiratory acclimation to moderate sustained hypoxia (6·0 kPa for 7 days at 22° C) in the bowfin Amia calva , a facultative air‐breathing fish. This level of hypoxia is slightly below the critical oxygen tension ( p crit ) of A. calva denied access to air (mean ± s.e . = 9·3 ± 1·0 kPa ). Before exposure to sustained hypoxia, A. calva with access to air increased air‐breathing frequency on exposure to acute progressive hypoxia while A. calva without access to air increased gill‐breathing frequency. Exposure to sustained hypoxia increased the gill ventilation response to acute progressive hypoxia in A. calva without access to air, regardless of whether they had access to air or not during the sustained hypoxia. Additionally, there was a decrease in Hb– O 2 binding affinity in these fish. This suggests that, in A. calva , acclimation to hypoxia elicits changes that increase oxygen delivery to the gas exchange surface for oxygen uptake and reduce haemoglobin affinity to enhance oxygen delivery to the tissues.