Effects of Mucosal Ions on Calcium Absorption in the Jejuno-ileum of the Goat in vitro

抄録

We, in the first experiment, observed changes in concentrations of minerals, short-chain fatty acids and osmolality along 6 parts of the caprine gastrointestinal tract. The concentrations of Na and HCO₃ and pH were lowest in the abomasum, changing reciprocally with those of Ca and Cl-. The concentration of Mg gradually (P<0.05) increased along the intestine. In the second experiment, we examined effects of changing medium ionic compositions on Ca absorption (a ratio of serosal to mucosal Ca concentration) in everted sacs of the jejuno-ileum. Ca absorption in a solution containing 41.2mmol/l MgCl₂ was greater than that in a solution containing 1.2mmol/l MgCl₂ (P<0.05). The effect of Mg on Ca absorption was dependent on the mucosal Mg concentrations (P<0.01). From these results, we conclude that in goats, a luminal Mg concentration, which increases along the intestine, accelerates Ca absorption in the jejuno-ileum.