Propriedades funcionais de hemoglobina e sangue completo em um mamífero aquático, o peixe-boi amazônico (Trichechus inunguis) ^*

Summary

Hematocrit (43%) and O₂ binding capacity (18.8 ml O₂/100 ml blood) of Trichechus inunguis blood are low compared to the values for other diving mammals but are similar to those for land mammals. Stripped manatee Hb is similar to human HbA In Its sensitivity to pH, 2,3-diphosphogIycerate and CO₂ but less sensitive to temperature and more prone to dissociate into dimers. The unique Hill plots exhibit no cooperativity below 30% O₂-saturation indicating a highly stabilized "T" or low affinity state(s): such asymmetric Hill plots together with biphasic O₂ - binding kinetics could mean chain heterogeneity The pH dependence of oxygen binding by the apparent "T" state, hemoglobin as seen in the Hill plots, is enhanced by 2,3 - diphosphoglycerate but eliminated by CO₂.