engleski

Magnesium absorption from different compartments of the swine large intestine

We studied magnesium absorption in the distal part of the swine intestine, as a function of different magnesium concentrations in the contents that may affect its absorption rate. The study was carried out in vitro by using sacs made of surviving mucous membrane of the caecum and proximal colon. The sacs were filled with magnesium chloride solutions containing magnesium at 0.5, 1.0, 2.5, 5, 10 or 20 mmol/L. The samples were collected on the submucosal side of the mucous membrane at the beginning of the experiment and 30, 60, 120 and 180 minutes later. Magnesium concentration in the samples was determined spectrophotometrically using the Titan yellow method. Increase of its concentration on the submucosal side was noticed already after 30 minutes from both compartments at all magnesium concentrations in the contents (P < 0.001). According to the presented results, at the lowest magnesium concentration in the contents, its absorption against the concentration gradient is possible from both compartments. The increase of magnesium concentration in the content to 10 or 20 mmol/L was accompanied by a significant increase of magnesium absorption from both compartments (P < 0.001). The lowest absorption rate of magnesium was achieved at 5 mmol/L of magnesium in the contents. The epithelium of the caecum was less resistant to low and proximal colon to high magnesium concentration in the contents. Our resultsindicate that the distal part of the swine digestive tract, i.e. the caecum and proximal colon, represent important sites of the magnesium absorption where magnesium was mostly absorbed by passive transport.

magnesium absorption; swine caecum; proximal colon

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