Anatomical distribution of exogenous 14C-oxalate in the rat by macroautoradiography

A single dose of 14C-oxalate was given to a group of laboratory rats using a gastric tube. The animals were then killed at intervals of 1/2, 2, 5, 24 and 72 h following oxalate administration and the oxalate distribution was determined using the technique of macroautoradiography. The results showed that a large proportion of the absorbed oxalate was already excreted in the bladder 30 min after administration. The non-absorbed oxalate was found eliminated with the faeces after 24 h. At the same time, 14C-oxalate was demonstrated in the bones; whereas 72 h later no radioactivity could be found anymore. It is conceivable, therefore, that the rapid renal excretion of exogenous oxalate may lead to a short-term oxalate peak in the urine. More importantly, the occurrence of such a urinary oxalate peak could in turn be responsible for crystalluria and stone formation.