Characteristics of Dipeptide Transport Kinetics in Small Intestinal Brush Border Membrane Vesicles of Piglets

In order to study the characteristics of dipeptide transport kinetics in small intestinal brush border membrane vesicles(BBMV) of piglets,radioactive isotope trace and in vitro incubation technique were used to observe the transmembrane transport of Gly-Pro under different condition.The results showed that:(1) Transport of Gly-Pro was inhibited significantly(P0.01) by Leu-Gly,Ala-His,Gly-Leu and His-Leu both in the presence and absence of a Na+ gradient,while not by Glycine,L-proline,L-leucine,L-arginine,L-glutamine and L-methionine;(2) The transport of Gly-Pro was nonlinear but followed by Michaelis-Menten kinetics.The kinetic constants suggested that the apparent Kt(affinity constant) value was 0.64 mmol/L,while V_(max) was 7.42 nmol/(min·mg)membrane protein;(3) The transport of Gly-Pro across the small intestinal BBMV of piglets was due to transport directly into the intravesicular space of BBMV rather than binding to vesicular membrane itself.It was suggested that transport of Gly-Pro in small intestinal BBMV of piglet posses characteristics of carrier-mediated transport.