Acute actions of 1,25-dihydroxyvitamin D3 upon chick pancreatic calbindin-D28K

We have compared the relative responsiveness of pancreatic, intestinal and renal tissue calbindin-D28K protein content to the stimulatory actions of 1,25-dihydroxyvitamin D3 1,25(OH)2D3] in vitamin D-deficient (-D) chicks. Tissue concentrations of calbindin-D28K were undetectable in the -D chick intestine but present, albeit at low concentrations (less than 1 microgram CaBP/mg protein) in the -D kidney and pancreas. Intestinal, pancreatic and renal calbindin-D28K content was stimulated 318, 9.8 and 2.9 fold respectively, 48 hours after -D chicks received a single dose of 1,25(OH)2D3 6.5 nmol/animal]. The pancreatic calbindin-D28K content could be significantly stimulated as early as 5 hours after 1,25(OH)2D3 administrations in vivo. These findings support the contention that the pancreas is a target for vitamin D, and is consistent with the view that calbindin-D28K plays a role in normal pancreatic functions.