Feeding augments canine jejunal absorption via a hormonal mechanism

The aim of this study was to determine whether hormones mediate the postprandial increase in absorption of water, glucose, and electrolytes that occurs in the canine jejunum. In four dogs, a 75-cm isolated loop of jejunum was extrinsically denervated by autotransplantation. After recovery, the loop was perfused at 2.8 ml/min with an isotonic solution of 130 mM glucose, 80 mM NaCl, and trace amounts of [14C]PEG. Mean transit times through the loop were assessed concurrently with 0.5-ml boluses of [3H]PEG. Experiments were performed during fasting and after an oral meal of 200 g liver. Under steady-state conditions, net absorption of water, glucose, sodium, and chloride was greater after feeding than during fasting. In contrast, mean transit times were nearly identical during fasting and after feeding. We concluded that the augmentation of jejunal absorption of water, glucose, and the electrolytes after feeding was brought about by mechanisms other than alterations in transit time or effects induced via the extrinsic nerves. The augmentation appeared to be mediated, in part, by hormones.