Effect of amino acid infusion on renal hemodynamics in humans.

The effect of amino acid (AA) infusion on renal hemodynamics was examined in 19 healthy subjects. Thirteen subjects participated in the first protocol (normal protein intake) and six in the second protocol (low protein intake). The first protocol consisted of three studies: study 1 (n = 13), AA were infused over 3 h to increase plasma amino acid levels two- to threefold; study 2 (n = 7), AA were infused with somatostatin and peripheral replacement of insulin, glucagon, and growth hormone; study 3 (n = 6), somatostatin was infused with basal hormonal replacement as in study 2. During study 1, glomerular filtration rate (GFR) rose by 20% (from 107 +/- 5 to 128 +/- 4 ml . 1.73 m-2 . min-1, P less than 0.001). Renal plasma flow (RPF) increased by a similar percentage (599 +/- 35 to 704 +/- 33 ml . 1.73 m-2 . min-1, P less than 0.001). When somatostatin was infused with AA (study 2), neither GFR nor RPF changed from base line. Somatostatin infusion alone (study 3) had no effect on GFR or RPF. During protocol 2, six subjects received a low-protein diet (40 g/day) for 7 days and AA were infused as per study 1. Base-line GFR (104 +/- 5 to 96 +/- 4 ml . 1.73 m-2 . min-1 and RPF (593 +/- 32 to 507 +/- 23 ml . 1.73 m-2 . min-1) both decreased (P less than 0.02) after the low-protein diet.(ABSTRACT TRUNCATED AT 250 WORDS)