SALT EXCRETION IN DESERT MAMMALS

Abstract

Rodents of the family Heteromyidae are able to thrive without water on a diet of dry grain. They conserve water by excreting a very concd. urine. Their urine, both with respect to salt and urea is much more concd. than hitherto found in other mammals. To find the upper limit for salt excretion in the urine, a heavy load of NaCl was imposed through the diet. The animals lost wt. when living on the salt diet, but they excreted a highly coned, urine. The highest chloride concn. found was 0.9 N (equal 5.3% NaCl). The highest electrolyte cone. was 1.22 N, which is more than twice as coned, as sea water.