Effects of extreme hemorrhage in hypoxically preconditioned pigeons, Columba livia

• Published in: The FASEB journal 2006-03, Vol.20 (5), p.A822-A822
• Main Authors: Benavidez, Kimberly Marie, Moya, Monica, Bernstein, Marvin H.
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.20.5.A822-c

Pigeons tolerate the loss of >90% of their blood by rapidly replacing the lost blood with an equal volume of tissue fluid. This prevents shock but causes extreme anemia. No data exist for birds about the effects of hypoxic preconditioning on responses to hemorrhage. We therefore placed arterially cannulated pigeons (mean mass 0.6 kg) in a chamber at 8% O2 for 3 h (H group) or at 21% O2 for 3 h (N group). A third group of pigeons was not preconditioned (C). Body mass was similar in H, N, and C. All birds were subjected to continuous blood withdrawal of ≤7% body mass at 0.4 ml/min. In H and N, hemorrhage began 24 h after preconditioning. During hemorrhage, hematocrit decreased significantly in all birds, reflecting red‐cell dilution. Body temperature and osmolarity, PO2, pH, PCO2, and HCO3 in blood were also maintained. Plasma lactate and glucose increased with blood loss to the same extent in all birds, reflecting increased anaerobic respiration. Plasma succinate was higher in H than in N or C, reflecting additional anaerobic ATP production through pathways activated by hypoxic preconditioning. The results suggest that hemorrhagic hypoxia in H may be compensated by anaerobic metabolism yielding both lactate and succinate, compared to lactate alone in N and C. Anaerobic metabolic pathways other than glycolysis alone have not previously been reported in birds and require further study (NIGMS grants GM61222, GM08136, and GM07667.)