Improved function with amino acids in the isolated perfused kidney

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Abstract
When isolated rat kidneys are perfused with glucose as the only substrate, there is a progressive diminution in glomerular filtration rate [GFR] and fractional reabsorption of Na. This is most marked after 1 h. Renal glutathione content rapidly falls and is < 30% of control levels after 1 h. Renal concentrating ability is markedly impaired and structural lesions are consistently observed in cells lining the thick ascending limb of Henle''s loop. Addition of 20 physiologic amino acids including cysteine to the perfusate prevents the fall in renal glutathione, prevents the anatomical damage to ascending limb cells, permits GFR and fractional Na reabsorption to remain high and close to their initial levels for as long as 4 h, and improves renal concentrating capacity. If amino acid supplementation is limited to the 3 precursors of glutathione (cysteine, glycine and glutamic acid), renal glutathione content is preserved and concentrating ability is improved, but GFR and fractional Na reabsorption are not maintained as well as with comprehensive amino acid supplements. Amino acid deficiency and glutathione depletion may contribute to disturbances in renal structure and function.