Respiration of 14CO2 by intact animals of various species given L-[1-14C]fucose or D-[1-14C]arabinose.

The production of 14CO2 from L-[1-14C]fucose and D-[1-14C]arabinose been studied in five mammalian species. Cats, guinea pigs, mice, and rabbits respired about 22% of the label of L-[1-14C]fucose or of D-[1-14C]arabinose within 6 h after intraperitoneal injection of the sugar. Rats respired only 1.5% of the L-fucose label and 5% of the D-arabinose label in the same time period. Liver homogenates from cat, guinea pig, and rabbit produced significantly more 14CO2 from L-[1-14C]fucose or D-[1-14C]arabinose than mouse or liver homogenates. Unlike those of the other species, guinea pig liver homogenates had very low L-fucose dehydrogenase activity. The results suggest that substantial catabolism of L-fucose and D-arabinose occurs in the tissues of some animal species. Investigators wishing to employ L-fucose as a tracer of glycoprotein metabolism must, therefore, ensure that the species that they employ does not metabolize L-fucose to products interfering with their studies.