Porphyrin synthesis and movement across human and rabbit red cell membrane with delta aminolaevulinic acid as substrate

Abstract

1. 1. Human and rabbit whole blood synthesize equal amounts of porphyrins with delta aminolaevulinic acid as substrate. 2. 2. However, whereas the porphyrins synthesized by human erythrocytes remain in the red cell, uro- and coproporphyrins synthesized by rabbit red cells move freely out of the cells and reach a greater extra than intracellular concentration. 3. 3. Inhibition of this porphyrin movement by sodium fluoride and 2,4-dinitrophenol suggests that the process is energy-dependent. 4. 4. Studies between Hank's balanced salt solution and plasma suggest that there is an essential factor in plasma for this movement, but that it is probably not protein-binding. 5. 5. Starch gel electrophoresis has shown that porphyrins in rabbit plasma are bound to an α-2-globulin fraction, and to albumen. 6. 6. Rupture of red cell membrane alters the pattern of porphyrin synthesis as compared to intact red cells. 7. 7. The results are discussed in relation to known facets of human porphyria and allylisopropylacetamide-induced porphyria in the rabbit.