Renal glutaminase I distribution and ammonia excretion in the rat

¹ Laboratory of Pathology and Histochemistry, National Institute of Arthritis and Metabolic Diseases, Bethesda, Maryland

Glutaminase I assays were made on carefully separated zones of kidneys from normal and acidotic rats. Highest activity in normal rats was found in the inner stripe of the outer medulla, next lower activity in the inner medulla (papilla), still lower activity in the cortex, and lowest activity in the outer stripe of the outer medulla. Induced acidosis produced a physiologically significant increase only in the activity of the cortex. Results are discussed in relation to previous conflicting reports. It is concluded that although urinary ammonia may be excreted by the papillary collecting tubules, its release is unlikely to result from glutaminase I activity at that site.