Effect of systemic bacterial infection on absorption rates of L-histidine and glycylglycine from the human jejunum in vivo.

Jejunal absorption rates of L-histidine (from a 100 mmole/liter solution) and glycylglycine (from a 50 mmole/liter solution) were determined with a souble-lumen tube perfusion system in vivo in 12 Zambian African men; six had acute bacterial pneumonia (infection group) and six had no clinical evidence of a bacterial infection (control group). With this experimental design the mean rate of histidine absorption was significantly higher in the infection compared with the control group, but mean rates for glycine absorption from glycylglycine were not significantly different. During the glycylglycine infusions, the luminal disappearance rate of the intact peptide was significantly greater than the total glycine absorption rate. The correlation between individual histidine and glycylglycine absorption rates was significant. That is probably because after intracellular hydrolysis and efflux to the lumen, some glycylglycine is reabsorbed as free glycine by the amino-acid transfer mechanism, and the rate of that has previously been shown to be increased in subjects with systemic bacterial infections.