Target cells for 1,25 dihydroxyvitamin D3 in the pancreas.

Mature rats raised on a vitamin D deficient diet were injected with tritium labeled, 1,25 dihydroxyvitamin D3. Concentration of radioactivity, which is prevented by pretreatment with unlabeled 1,25 dihydroxyvitamin D3, is found in nuclei of cells that are centrally located in pancreatic islets. The central location of these cells and supportive evidence from the literature suggest that they are B-cells, and that 1,25 dihydroxyvitamin D3 has a direct and genomic action on B-cell functions including insulin secretion.