1. The distribution of the 1α,25-dihydroxycholecalciferol receptor was studied in enterocytes isolated from the upper, mid and lower villus and crypt cells of the jejunum of normal and rachitic rats.

2. In all cell fractions a high-affinity receptor (KD ⋍ 0.07 nmol/l) with a sedimentation coefficient of 3.5S was demonstrated.

3. In normal rats there was a 60% reduction in receptor numbers in crypt cells compared with the mid and upper villous cells.

4. Vitamin D deficiency led to a reduction in receptor numbers in all cell fractions (45% upper villus, 78% crypt cells).

5. The data are compatible with the concept of calcium absorption occurring in the differentiated villous cells and also account for the reduction in absorption in rachitic animals.

Keywords:
calcium metabolism, 1,25-dihydroxy-vitamin D receptors, small intestine
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© 1984 The Biochemical Society and the Medical Research Society
1984
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