Absorption of L-histidine and glucose from the jejunum segment of the pig and its diurnal fluctuation

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Abstract
1. Flow rate of digesta and its components in the upper jejunum, and the absorption of L-histidine and glucose from the jejunum segment were measured in pigs fitted with three simple cannulas. The pigs were fed once daily at 08.30 hours.2. A maximum flow of digesta was obtained in the period 10.00–10.30 hours; the flow rate decreased with time after feeding, reaching a minimum in the period 22.00–22.30 hours.3. The absorption rate for L-histidine and glucose increased in a hyperbolic manner with increasing concentrations of infused test material, which ranged from 2.5 to 20 g/l for each material.4. L-histidine and glucose were absorbed nearly independently when perfused in combination. The absorption rates for glucose were significantly (P< 0.01) greater than the corresponding rates for L-histidine at each concentration of infusate.5. The absorption of both L-histidine and glucose expressed as a percentage of the amounts in the perfusate decreased with increasing flow rate of perfusate, from 400 to 800 ml/h. The increase in flow rate from 400 to 800 ml/h was associated with a 20% increase in L-histidine absorption rate; there was a 30% increase in glucose absorption rate when the flow rate was increased to 600 ml/h, but no further increase at 800 ml/h.6. The absorption of both L-histidine and glucose decreased with time after feeding; the absorption rates for L-histidine and glucose measured for the period 10.00–10.30 hours were 126 and 133%, respectively, of those measured for the period 22.00–22.30 hours.