Overall renal and tubular function during infusion of amino acids in normal man.
نویسندگان
چکیده
1. Amino acids have been used to test renal reserve filtration capacity. Previous studies suggest that amino acids increase glomerular filtration rate (GFR) by reducing distal tubular flow and tubuloglomerular feedback activity. 2. Glomerular function and the renal tubular handling of sodium during infusion of amino acids was studied in 12 normal volunteers. 3. Clearance of sodium (CNa) was unchanged. Effective renal plasma flow increased slightly, but significantly, by 9% (P less than 0.05). GFR was increased by 13% (P less than 0.001). Clearance of lithium (CLi) (used as an index of proximal tubular outflow) increased by 38% (P less than 0.001). Calculated absolute proximal reabsorption (GFR-CLi) remained unchanged. Fractional proximal reabsorption [1-(CLi/GFR)] was decreased by 10% (P less than 0.001). Calculated absolute distal sodium reabsorption [(CLi-CNa) x PNa, where PNa is plasma sodium concentration] increased by 40% (P less than 0.001). Plasma renin concentration did not change significantly. 4. The results suggest that amino acids increase GFR by a primary effect on renal haemodynamics or, less likely, by reducing the signal to the tubuloglomerular feedback mechanism. The increase in proximal tubular outflow was compensated for in the distal tubules, so that the sodium excretion rate remained unchanged.
منابع مشابه
Renal effects of amino acids and dopamine in renal transplant recipients treated with or without cyclosporin A.
1. The nephrotoxic effects of cyclosporin A may diminish the ability of the transplanted kidney to increase the glomerular filtration rate and effective renal plasma flow during infusion of dopamine or amino acids. 2. The present study included 16 renal transplant recipients transplanted for more than 6 months. Eight of the patients were on immunosuppressive treatment including cyclosporin A [c...
متن کاملRenal transport of lysine and arginine in cystinuria.
To study the defective transport mechanism of cystinuria, renal tubular reabsorption of lysine or arginine in normal and cystinuria subjects was investigated by increasing the filtered load employing intravenous amino acid infusion. In the normal group the amino acid reabsorption rose with increases of the filtered load and reached a maximum (Tm). In the cystinuria group the elevation of amino ...
متن کاملLysine infusion in cystinuria: theoretical renal thresholds for lysine.
1. The renal handling of lysine was studied during the intravenous infusion of a lysine load given in such a way that the plasma lysine concentration was constantly increasing. Theoretical renal thresholds, and maximum rates of renal tubular reabsorption of lysine, have been determined in three normal adults, five homozygous cystinuric patients, and three persons, two ‘completely’ and the third...
متن کاملPrevalence of renal tubular dysfunction in beta thalassemia minor in shiraz
Background & objective: β-Thalassemia minor is an asymptomatic hereditary disease. The first study on the relation of renal tubular dysfunction and β-thalassemia minor was performed in 2002 but those studies seem inadequate.The main goal of this study is through evaluation of renal tubular function in 100 patients with thalassemia minor. Materials & Methods: 100 patients with β- thalassemia...
متن کاملRenal tubular transport of proline, hydroxyproline, and glycine. II. Hydroxy-l-proline as substrate and as inhibitor in vivo.
Renal tubular absorption of the free amino acids L-proline, hydroxy-L-proline, and glycine in man is accomplished by a transport system exhibiting preference for this group of amino acids (1, 2). The characteristics of saturability (for L-proline transport) and selective inhibition between the constituent substrates have been demonstrated for this system in man (1). Studies in vivo in the rat (...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Clinical science
دوره 78 5 شماره
صفحات -
تاریخ انتشار 1990