In vitro kinetics of oxygen transport in erythrocyte suspension or unmodified hemoglobin solution from human and other animals

Oxygen transport behavior in erythrocyte suspension or in hemoglobin solution was studied as a potential therapeutic model for the clinical treatment of blood loss, and this can also provide physiological data with which to evaluate blood substitutes. In the present project, we examined the in vitro kinetics of hemoglobin binding to and releasing oxygen, to provide detailed oxygen-flux measurements for unmodified hemoglobin solutions and erythrocyte suspensions in human, as well as other vertebrates. An in vitro method was used, based on a widely used artificial system, with the oxygen saturation level being detected in real time. Results from this study indicated that the kinetic curves of human erythrocyte suspensions and hemoglobin solutions were either S-shaped or hyperbolic, respectively. Based on these curves, the significance of [T.sub.50] emerged in our investigation, where [T.sub.50] is defined as the time needed for 50% hemoglobin to be saturated with oxygen, and reflects the efficiency with which hemoglobin carries oxygen. This parameter may be used to diagnose blood diseases, and could be a standard for evaluating blood substitutes. In this study, we also compared the [T.sub.50] of 4 species of vertebrates, and found that it shows a distinct efficiency of oxygen binding related to species, and potentially reveals the evolutionary function of hemoglobin and its possible adaptation to the environment. Key words: oxygen transport, kinetic curve, erythrocyte, hemoglobin, [T.sub.50]. Le transport d'oxygene chez les erythrocytes ou dans une solution d'hemoglobine a ete etudie en tant que modele therapeutique potentiel pour traiter cliniquement la perte sanguine et pour fournir aussi des donnees physiologiques permettant d'en evaluer la valeur comme substituts sanguins. Dans le present projet, nous avons examine les cinetiques de liaison et de liberation d'oxygene par l'hemoglobine in vitro afin d'obtenir des mesures detaillees du flux d'oxygene dans des solutions d'hemoglobine non modifiee et des suspensions d'erythrocytes chez l'humain ainsi que chez d'autres vertebres. Une methode in vitro basee sur un systeme artificiel largement employe a ete utilisee et le niveau de saturation en oxygene a ete detecte en temps reel. Les resultats de cette etude ont indique que les courbes cinetiques des suspensions d'erythrocytes et des solutions d'hemoglobine d'origine humaine etaient respectivement en forme de S et hyperbolique. Selon ces courbes, l'importance du [T.sub.50] est ressortie de nos travaux. Le [T.sub.50] est defini comme le temps requis pour atteindre 50 % de saturation en oxygene et reflete l'efficacite de transport d'oxygene de l'hemoglobine, ce qui peut contribuer au diagnostic des maladies sanguines et constituer un standard des substituts sanguins. Dans cette etude, nous avons aussi compare les [T.sub.50] de 4 especes de vertebres, lesquels montrent des efficacites de liaison d'oxygene distinctes et revelent potentiellement la fonction evolutive de l'hemoglobine et son adaptation possible a l'environnement. Mots-cles : transport d'oxygene, courbe cinetique, erythrocytes, hemoglobine, [T.sub.50]. [Traduit par la Redaction]
Introduction The hemoglobin oxygen dissociation curve (HODC), including [P.sub.50] (the partial pressure of [O.sub.2], where 50% of the hemoglobin is saturated) is widely used as a criterion for assessing the [...]