Intrarenal mechanisms of renal reserve.

Acute ingestion of protein and intravenous infusion of amino acids are known to stimulate increases in renal blood flow and glomerular filtration rate (GFR) in animals and humans. Although some investigators believe that these changes are mediated by a circulating hormonal factor, there is considerable evidence that intrinsic intrarenal mechanisms such as tubular transport of amino acids and sodium, and the tubuloglomerular feedback mechanism, are involved in this renal hemodynamic response, and that extrarenal factors may not be required.