Transport of putrescine across duodenal, jejunal and ileal brush-border membrane of chicks ( Gallus domesticus)

Abstract

Luminal polyamines and their absorption are essential for proliferation of the enterocytes and, therefore, nutrition, health and development of the animal. The transport systems that facilitate the uptake of putrescine were characterized in chick duodenal, jejunal and ileal brush-border membrane vesicles prepared by MgCl 2 precipitation from three-week-old chicks. An inwardly-directed Na + gradient did not stimulate putrescine uptake and, therefore, putrescine transport in chick intestine. In the duodenum, jejunum and ileum, kinetics of putrescine transport fitted a model with a single affinity component plus a non-saturable component. The affinity ( K t ) for [ 3H]putrescine transport across the brush-border membrane increased along the length of the small intestine. A model of intermediate affinity converged to the data obtained for [ 3H]putrescine transport with K t approximating 1.07 and 1.05 mM or duodenum and jejunum, respectively; and high affinity with a K t of 0.35 mM for the ileum. The polyamines cadaverine, putrescine, spermidine and spermine strongly inhibited the uptake of [ 3H]putrescine into chick brush-border membrane vesicles, more so for the jejunum and ileum than the duodenum. The kinetics of cadaverine, spermidine and spermine inhibition are suggestive of competitive inhibition of putrescine transport. These uptake data indicate that a single-affinity system facilitates the intestinal transport of putrescine in the chick; and the affinity of transporter for putrescine is higher in the ileum than in the proximal sections of the small intestine. In addition, this study shows that the ileum of chicks plays an important role in regulating cellular putrescine concentration.