L-Prolylglycine

Wistar (male, 180-360 g body weight)^[1]

10 mM; 40 mM (co-infused with 10 mM glycyl-L-proline)

intestinal perfusion; single steady-state infusion

Exhibited significantly slower glycine absorption rate (2.06 μmole 5 min^-1·g wet wt^-1) in jejunum compared to free amino acids (3.37 μmole 5 min^-1·g wet wt^-1, P < 0.05).
Exhibited significantly slower proline absorption rate (2.09 μmole 5 min^-1·g wet wt^-1) in jejunum compared to free amino acids (3.63 μmole 5 min^-1·g wet wt^-1, P < 0.05).
Exhibited significantly slower glycine absorption rate (1.89 μmole 5 min^-1·g wet wt^-1) in ileum compared to free amino acids (3.54 μmole 5 min^-1·g wet wt^-1, P < 0.02).
Exhibited significantly slower proline absorption rate (1.93 μmole 5 min^-1·g wet wt^-1) in ileum compared to free amino acids (3.46 μmole 5 min^-1·g wet wt^-1, P < 0.02).
Showed negligible free glycine (0.07 μmole mL^-1) and proline (0.04 μmole mL^-1) in jejunal luminal aspirates, with significantly higher concentrations detected in ileal aspirates (glycine: 0.28 μmole mL^-1; proline: 0.23 μmole mL^-1, P < 0.001 vs. jejunum).
Had a jejunal disappearance rate of 1.57 μmole 5 min^-1·g wet wt^-1, which was reduced to 0.88 μmole 5 min^-1·g wet wt^-1 (42.2% inhibition, P < 0.05) upon co-infusion with 40 mM glycyl-L-proline.
Exhibited slower disappearance rate than 10 mM glycyl-L-proline in jejunum (2.44 vs. 4.20 μmole 5 min^-1·g wet wt^-1, P < 0.02) and ileum (2.00 vs. 4.41 μmole 5 min^-1·g wet wt^-1, P < 0.001).