Calcium-dependent translocation of calbindin-D28k from intestine to blood.
Arch Biochem Biophys
; 261(1): 27-34, 1988 Feb 15.
Article
em En
| MEDLINE
| ID: mdl-3341776
ABSTRACT
Calbindin-D (vitamin D-induced calcium-binding protein; CaBP) is known to be present in blood at concentrations which vary directly with levels in the intestinal mucosa. Employing a sensitive radioimmunoassay and sampling mesentery venous blood, the present experiments demonstrated a direct relationship between intestinal calcium absorption and serum CaBP. Solutions containing 150 mM NaCl and 45Ca-labeled calcium chloride (5 or 20 mM) were placed in the lumen of ligated duodenal preparations in situ and mesentery venous blood sampled with time. The concentration of absorbed 45Ca in serum was maximal at 5 min, followed by a significant increase in mesentery CaBP maximizing at 15-20 min. Elevation of serum CaBP was not observed when calcium in the dosing solution was omitted or replaced by either glucose or glycine. The possible transfer of absorbed calcium from the enterocyte to the circulation as a CaBP complex was ruled out by calculations revealing that considerably more calcium was transferred than could be accounted for by the low and high affinity binding sites on the protein. It is proposed that vitamin D-dependent enhanced transcellular calcium transport constitutes a stimulus for the increased release of intestinal CaBP into the circulation.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteína G de Ligação ao Cálcio S100
/
Duodeno
/
Mucosa Intestinal
Limite:
Animals
Idioma:
En
Revista:
Arch Biochem Biophys
Ano de publicação:
1988
Tipo de documento:
Article