Glutamine and glutaminase in blood.

R.ECENTLY THE NEED of a method for the determination of glutamine and glutaminase in the blood and urine of humans led to the evaluation and adaptation of a single system for both. Methods of glutamine assay available depend on the determination of the ammonia liberated by mild hydrolysis with dilute hydrochloric, sulfuric, or trichioroacetic acid, or alkali, heat at neutral pH, or the action of the specific enzyme, glutaminase (1). Other methods measure the decreased reactivity with nitrous acid or ninhydrin that occurs when glutamine undergoes hydrolysis and condensation to ammonium pyrrolidone carboxylate. Krebs (2) demonstrated that the cortex of kidneys of sheep, guinea pig, pig, and rabbit contained an enzyme, glutaminase, which hydrolyzes glutamine to ammonia and glutamic acid. Archibald (3) has described the preparation and standardization of kidney glutaminase in a form which makes the enzyme readily applicable for microestimation of glutamine in blood and other biologic materials. Seegmiller, Schwartz, and Davidson (4) have described a glutaminase preparation of bacterial origin. It has been observed in rats that renal glutaminase activity increases fourfold during adaptation to ammonium chloride acidosis (5). This led us to choose rats previously treated with NH4C1 as the source of glutaminase preparation.