Oxalate Metabolism in the Pack Rat, Sand Rat, Hamster, and White Rat

Abstract

Soluble oxalates are toxic because they bind calcium in the organism and are not metabolized, but certain rodents appear to be able to tolerate a considerable amount of soluble oxalates and to absorb calcium from insoluble calcium oxalate. The metabolism of oxalates by pack rats (Neotoma albigula), hamsters (Mesocricetus auratus), sand rats (Psammomys obesus) and Osborne-Mendel white rats (Rattus norvegicus) was investigated by (a) feeding insoluble calcium oxalate and studying the degradation of the oxalate and the excretion of calcium in the urine; (b) feeding 14C-labeled soluble oxalate and observing its metabolism; and (c) injecting 14C-oxalate and following its elimination from the body. When calcium oxalate was fed, some of the oxalate was degraded and some of the calcium appeared in the urine of pack rats, hamsters, and sand rats, but white rats did not metabolize oxalate or increase calcium excretion. When soluble oxalate was ingested, three of the rodents degraded almost all of it, but white rats degraded only half. Injected oxalate was excreted in the urine by pack rats and hamsters, some sand rats excreted oxalate and others degraded it, and white rats eliminated half in the urine and half in the feces. These observations suggest that oxalate degradation takes place in the intestine, presumably by microbial action.