Diabetes and Renal Calcium Binding Protein in the Rat

H. P. Schedl, S. Christakos, H. D. Wilson, L. Malkowitz, R. L. Horst

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Renal calcium binding protein (CaBP), a vitamin D-dependent protein of 28,000 M r, may be involved in calcium transport by cells of the renal tubule. The streptozotocin-diabetic rat is hypercalciuric and shows markedly decreased concentration of 1,25-dihydroxy-cholecalciferol [1,25-(OH)2D3] in serum and of CaBP in small intestine. To examine the relationship of renal CaBP in diabetes to 1,25-(OH)2D3 and urinary calcium excretion, renal CaBP, serum 1,25-(OH)2D3, and urinary calcium were measured in control, diabetic, and insulin–treated diabetic rats. Treatment of the diabetic rat with insulin decreased urinary calcium excretion and elevated 1,25-(OH)2D3 toward normal. Renal CaBP was found to be the same in controls and diabetics despite a tenfold difference in concentration of 1,25-(OH)2D3 in serum, and to be unaffected by insulin treatment, which elevated 1,25-(OH)2D3 by a factor of 7 above untreated diabetics. It is concluded that in the diabetic rat either (1) the threshold concentration of 1,25-(OH)2D3 for inducing synthesis of renal CaBP is set at a much lower level than that for intestinal CaBP, or (2) since both 1,25-(OH)2D3 and renal CaBP are produced in the kidney, 1,25-(OH)2D3 exerts a paracrine effect on renal CaBP production because of its high local concentration. The increased urinary calcium excretion in the untreated streptozotocin-diabetic rat is not secondary to an alteration in renal CaBP.

Original languageEnglish (US)
Pages (from-to)176-179
Number of pages4
JournalProceedings of the Society for Experimental Biology and Medicine
Volume177
Issue number1
DOIs
StatePublished - Oct 1984
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)

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