Abstract
Summary: Using a marker perfusion technique, the amino acid absorption in the jejunum from test solutions containing glycine and phenylalanine (30 mM/liter each) was studied in three patients with the Fanconi syndrome. Uptake rates (mM/min/20-cm segment) in two cystinotic patients were found to be 55.2 and 76.1 for glycine and 74.5 and 107.5 for phenylalanine. In a patient with idiopathic Fanconi syndrome the rates were 16.5 for glycine and 41.9 for phenylalanine, respectively. If the results are compared to those of healthy controls (74.5 ± 10.3 for glycine and 107.8 ± 10.6 for phenylalanine, respectively) the intestinal absorption of ammo acids is normal or slightly decreased in patients with cystinosis but impaired in the latter patient.
Wistar rats treated twice with an injection of maleic acid (3.2 mM/kg body weight) were used to study the intestinal absorption in vivo and in vitro. Ten cm of the jejunum of anaesthetized animals were perfused with a solution consisting of 0.5, 1.0, or 5.0 mM/liter phenylalanine, and the absorptive capacity was calculated from the disappearance of amino acids from the test solutions. The maleic-acid-treated animals exhibited slightly lower rates only at the 5.0 mM/liter concentrations (P < 0.05).
The in vitro uptake of phenylalanine and cycloleucine was studied in scraped epithelium of the jejunum. Uptake of both substrates occurs against a concentration gradient, but their transfer was not inhibited by treatment with maleic acid. In contrast, the intracellular accumulation of substrates was found to be higher in the treated animals. Results of these animal studies indicate that maleic acid induces changes of intestinal function, but that inhibition of amino acid absorption does not occur. Comparable to the absorption defect in kidney tubules the Fanconi syndrome may also affect absorptive function in gut mucosa.
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Nützenadel, W., Fahr, K. & Hammersen, G. Intestinal Amino Acid Absorption in the Fanconi Syndrome: Studies in Patients and in Rats with the Maleic Acid Induced Syndrome. Pediatr Res 17, 710–713 (1983). https://doi.org/10.1203/00006450-198309000-00004
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DOI: https://doi.org/10.1203/00006450-198309000-00004