Abstract
A proline-deficient (PD) diet was fed to rats to attain the same proline concentrations in blood plasma as those in fasting animals. Plasma amino acid concentrations in the carotid artery and renal vein (arteriovenous difference), and renal vein blood flow were measured. The findings suggest that, with a control diet, renal proline uptake occurs when the carotid arterial proline concentration is higher than when fasting, and with a PD diet, renal proline release occurs when the plasma proline concentration is equal to that during fasting. Eight hours after feeding, a high negative correlation existed between the arteriovenous difference of arginine concentration and the plasma proline concentration in the carotid artery (γ=-0.816, p<0.01). The above findings suggest that the release and uptake of proline by the kidney depend on the carotid arterial proline level, and that renal arginine release, which is vital for normal growth, decreases temporarily in response to dietary proline deprivation.
