Intestinal response to 1α,25-dihydroxycholecalciferol I. RNA polymerase, alkaline phosphatase, calcium and phosphorus uptake in vitro, and in vivo calcium transport and accumulation

• Published in: Biochimica et biophysica acta Vol. 538; no. 1; pp. 23 - 33
• Main Authors: Morrissey, Robert L., Zolock, David T., Bikle, Daniel D., Empson, Richard N., Bucci, Thomas J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 03.01.1978
• Subjects: Alkaline Phosphatase - metabolism; Animals; Bone and Bones - metabolism; Calcium - metabolism; Carrier Proteins - metabolism; Chickens; Dihydroxycholecalciferols - pharmacology; DNA-Directed RNA Polymerases - metabolism; Duodenum - metabolism; Hydroxycholecalciferols - pharmacology; Intestinal Mucosa - metabolism; Male; Phosphorus - metabolism; Rickets - metabolism
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/0304-4165(78)90248-9

The dynamics of intestinal response in rachitic chicks to 1α,25-dihydroxycholecalciferol were evaluated by various biochemical parameters. The following observations were made: 1. 1. The earliest detected intestinal response to 1α,25-dihydroxycholecalciferol was increased in vitro calcium uptake and in vivo calcium transport, occurring by 2 h and 2.5 h respectively. 2. 2. Increased RNA polymerase activity was observed by 4 h after 1α,25-dihydroxycholecalciferol treatment. 3. 3. Calcium binding protein was detected by 5 h, but could not be detected 2.5 h after 1α,25-dihydroxycholecalciferol treatment. 4. 4. Increased alkaline phosphatase activity and in vitro accumulation of inorganic phosphate were first demonstrable 6 h after 1α,25-dihydroxycholecalciferol treatment. 5. 5. In vivo duodenal calcium accumulation in the mucosa was elevated after 5 h, peaked at 6.5 h, and then began to decrease at 9 h. In vitro duodenal calcium accumulation was elevated at 2 h, peaked at 12 h, and decreased to control level by 18 h. Our data emphasize the lack of correlation between the appearance of calcium binding protein or increased alkaline phosphatase activity and the transport rate of calcium across the duodenum after treatment with 1α,25-dihydroxycholecalciferol. The data suggest a correlation between duodenal calcium accumulation and the appearance of calcium binding protein or increased alkaline phosphatase activity.