Gastrointestinal absorption of lead in chicks: involvement of the cholecalciferol endocrine system
The role of dietary calcium and phosphorus in modifying the intestinal absorption of lead and also the effect of lead ingestion on the metabolism of cholecalciferol were studied in chicks. The efficiency of absorption of /sup 203/Pb and /sup 47/Ca was increased when the animals were fed a low calcium diet and treated with cholecalciferol. The synthesis of the vitamin D-induced calcium-binding protein (CaBP) was correspondingly increased. When the chicks were depleted of vitamin D and repleted with 1,25-dihydroxycholecalciferol (1,25(OH)/sub 2/D/sub 3/) as their only source of the vitamin, the absorption of both /sup 47/Ca and /sup 203/Pb was unaffected by dietary calcium levels, and no change in CaBP levels occurred. Low dietary intake of phosphorus resulted in an increase in /sup 47/Ca and /sup 203/Pb absorption and in CaBP synthesis when the animals were treated with cholecalciferol. However, when the birds were repleted with 1,25(OH)/sub 2/D/sub 3/, the intestinal absorption of /sup 47/Ca and of /sup 203/Pb was increased, as well as the intestinal CaBP levels. Intracardial injection of increasing doses of 1,25(OH)/sub 2/D/sub 3/ to rachitic chicks resulted in a concomitant increase in /sup 203/Pb absorption in a manner that correlated with the degree of synthesis of CaBP. Ingestion of lead by the chicks was found to impair growth and renal production of 1,25(OH)/sub 2/D/sub 3/, resulting in lowered circulating and intestinal content of the hydroxylated metabolites of cholecalciferol.
- Research Organization:
- Department of Physiology, New York State College of Veterinary Medicine, Cornell University, Ithaca
- OSTI ID:
- 6728648
- Journal Information:
- J. Nutr.; (United States), Vol. 114:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
CALCIUM
INTESTINAL ABSORPTION
CHOLECALCIFEROL
BIOLOGICAL EFFECTS
LEAD
PHOSPHORUS
CALCIUM 47
CHICKENS
GROWTH
LEAD 203
LIQUID COLUMN CHROMATOGRAPHY
ABSORPTION
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIRDS
CALCIUM ISOTOPES
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
FOWL
HEAVY NUCLEI
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LEAD ISOTOPES
METALS
NONMETALS
NUCLEI
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
SEPARATION PROCESSES
UPTAKE
VERTEBRATES
VITAMIN D
VITAMINS
550501* - Metabolism- Tracer Techniques
560305 - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)