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Mitochondrial plasticity in the anoxic turtle heart
Author(s) -
Galli Gina LJ,
Richards Jeffrey
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.859.9
Subject(s) - anoxic waters , respirometer , respiration , acclimatization , biology , mitochondrion , electron transport chain , biochemistry , chemistry , anatomy , ecology
Our objective was to assess mitochondrial respiration and electron transport chain (ETC) activities in permiabilised cardiac fibers from normoxic and anoxic (2 weeks) turtles ( Trachemys scripta ) acclimated to 5°C. All experiments on animals were conducted in conformance with the FASEB Principles. Mitochondrial maximum ADP stimulated respiration was measured with an Oroboros micro‐respirometer, and respiratory flux through complex I, II and IV of the ETC was assessed by pharmacological intervention. ADP affinity was determined by adding ADP in steps from 0.025 mM to a maximum of 1 mM. All preparations were tested at 5, 13 and 21°C. Anoxic acclimation led to significant reductions in maximum respiration rates through ETC complexes I, II and IV at all temperatures tested, and ADP affinity was significantly lower. State II respiration rates were significantly reduced in anoxic cardiac fibers, leading to a higher respiratory control ratio, which is indicative of a reduction in proton leak. Collectively, these results suggest a reduction in mitochondrial capacity contributes to overall hypometabolism in anoxic turtles. Since complex I of the ETC is a major site of reactive oxygen species generation, a downregulation of this protein may also help to prevent redox damage during anoxic recovery. This research was funded by The Killam Memorial Trust and The Natural Sciences and Educational Research Council of Canada.