Kidney Glutaminase and Carbonic Anhydrase Activities and Renal Electrolyte Excretion in Rats

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Abstract
The plasma electrolyte composition and 24-hour urine electrolyte excretion were determined in fasting normal, K-deficient and protein and K-deficient rats following the administration of equal molar quantities of NaCl, KCl, NH4Cl and KHCO3. An attempt was made to relate any differences in the compositions of the plasma and urine to the levels of renal glutaminase and carbonic anhydrase activities, and, to the chemical compositions of the skeletal muscle and kidneys. Renal glutaminase and carbonic anhydrase activities were found increased in K-deficiency and reduced in protein and K-deficiency. Significant changes from corresponding control levels of renal glutaminase were found in normal and K-deficient animals only after the administration of NH4Cl (increased), and, after the administration of KHCO3 (reduced). The only outstanding change of the carbonic anhydrase activity of the kidneys from these animals was a reduction following NH4Cl administration. The doubly deficient rats showed a significant increase in renal glutaminase activity after NH4Cl administration; on the other hand, KCl administration resulted in a further reduction of the lowered renal carbonic anhydrase activity. The experimental results supported the contention that a relationship exists between urinary ammonia excretion and the level of renal glutaminase activity, while the transfer of H+ to the urine and the level of renal carbonic anhydrase activity could not be related. No clear relationship was found between the K excretion and/or K content of the kidneys and the urine total titratable acidity and ammonia excretion, and urine ph.

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