Intestinal oxygenation and mucosal permeability with luminal mother's milk in developing piglets

We have previously observed a developmental difference in mucosal permeability (i.e. the younger the animal, the greater the increase in permeability) after exposure to luminal nutrients derived from cow's milk-based infant formulas. There has been tremendous speculation and some clinical evidence that mother's milk may be protective against mucosal injury in developing intestine. In this study, we hypothesized that instillation of sow's milk into the intestinal lumen of developing piglets would cause no differences in either intestinal metabolic demand (oxygen uptake) or mucosal permeability among age groups. Intestinal blood flow (total and fractionated), arteriovenous oxygen content difference, venous pressure, and capillary pressure were measured, and vascular resistance and oxygen uptake were calculated, after 30 min of intraluminal instillation of predigested and solubilized sow's milk in 1-d-old, 3-d-old, 2-wk-old, and 1-mo-old piglet jejunoileum. In a separate group of animals, plasma-to-lumen clearance of chromium-51 EDTA was evaluated during luminal perfusion with digested and solubilized sow's milk in 1-d-old, 3-d-old, and 1-mo-old piglet jejunoileum. Intestinal oxygen uptake was similar among age groups of developing piglets, but EDTA clearance was significantly higher for intestinal segments perfused with sow's milk in 1-d-old, compared with older, animals. Thus, luminal perfusion with predigested and bile acid-solubilized sow's milk in 1-d-old piglet jejunoileum, compared with perfusion in older piglets, causes increased mucosal permeability in 1-d-old intestine, but this increased permeability is not due to increased intestinal oxygen uptake (i.e. increased metabolic demand).