Calcium-binding protein in the duodenal mucosa of uremic patients and normal subjects

Abstract

In the present study we measured the content and determined the localization of a calcium-binding protein (CaBP) in the intestinal biopsy specimen of ten patients with severe renal insufficiency and in eight healthy individuals. In each patient a biopsy specimen of the iliac crest was obtained for evaluation of the degree of osteodystrophy. The CaBP was isolated from human kidneys. Its identity with human intestinal CaBP was suggested by acrylamid gel electrophoresis. Specific antibodies against it were developed in rabbits. The content of CaBP in duodenal mucosa biopsy material was measured by quantitative radial immunodiffusion. Its mean value in the duodenum of patients with renal insufficiency was 3.65 +/- 1.14 mug; in that of normal persons, 10.80 +/- 3.20 mug/mg of protein in the supernatant. There was neither a correlation between the type and duration of renal insufficiency and the CaBP content of the specimens nor between the degree of renal osteodystrophy and CaBP content. In normal persons the specific immunohistological activity indicating the presence of CaBP was found uniformly along the brush border and basement membrane of duodenal epithelial and the goblet cells. In uremic patients the fluorescence was markedly reduced in the typical locations, especially in the brush border area.