[Differences between human and rat blood towards 3,4-dihydroxy-L-phenylalanine and 5-hydroxy-L-tryptophan in vitro. Biochemical and histochemical data (author's transl)]

When incubated with whole human blood at ordinary temperature, 3,4-dihydroxy-L-phenylalanine remains unchanged for at least 30 min. Under the same experimental conditions, 5-hydroxy-L-tryptophan shows a tendency to decrease. When incubated with blood from pentobarbital anaesthetized rats, these aminoacids decrease to about 50% of the added quantity in less than 5 min; thereafter, their level remains stable (3,4-dihydroxy-L-phenyl-alanine) or slowly decreases (5-hydroxy-L-tryptophan).