β-Carotene-Induced Alterations in Haemoglobin Affinity to O₂

Abstract

β-Carotene (β-Crt) can be dispersed in hydrophobic regions of the membrane of red blood cells (RBC). Its location, orientation and distribution strongly depend on carotenoid concentration. In the present pilot trial (six human subjects involved), it is demonstrated that incubation of RBCs with β-Crt (1.8 × 107 β-Crt molecules per RBC, 50 μmol/L) results in expansion of the membrane of RBCs and slight elongation of the cell. The changes are of statistical significance, as verified by the Wilcoxon test at p 8 β-Crt molecules per RBC (500 μmol/L). Due to the reduced permeability of ions, such membranes exhibit increased resistance to haemolysis. Finally, we show that interactions of β-Crt with the membrane of RBCs lead to an alteration in haemoglobin-oxygen affinity, shifting the oxyhaemoglobin dissociation curve toward higher oxygen partial pressures. If the impact of β-Crt on a curve course is confirmed in vivo, one may consider its role in the fine tuning of O2 transportation to tissues. Hence, at low concentrations, providing unchanged elastic and functional properties of RBCs, it could serve as a beneficial agent in optimising heart performance and cardiovascular load.

Keywords

• β-carotene
• haemoglobin
• osmotic fragility
• oxygen affinity
• red blood cell