Small intestinal epithelial permeability to water soluble nutrients higher in passerine birds than in rodents

ANTONIO BRUN; CINTIA GARRO; KARASOV WH; CAVIEDES-VIDAL E

JOURNAL OF ANIMAL PHYSIOLOGY AND ANIMAL NUTRITION

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0931-2439

In the small intestine transcellular and paracellular pathways are implicated in water-soluble nutrients absorption. In small birds the paracellular pathway is quantitatively important while transcellular pathway is much more important in terrestrial mammals. However, there is not a clear understanding of the mechanistic underpinnings of the differences among taxa. The aim of this study was to test the prediction that paracellular permeability in perfused intestinal segments will be higher in passerine birds than rodents. Birds exhibited ~2 to ~3 times higher L-arabinose clearance than rodents; these differences may be explained by differences in intestinal permeability and not by other factors. Absorption of 3-O-methyl-D-glucose and L-proline in birds had a significantly higher paracellular proportion than rodents. The analysis of our results and all the existing data (birds, bats, rodents) shows that insectivorous species only had 30% of the clearance of L-arabinose of noninsectivorous species. This result may be explained by the fact of aweaker natural selection for high paracellular permeability in carnivores and insectivores compared to herbivores and omnivores. This finding is consistent with the idea of a tradeoff between the putative benefit of high intestinal paracellular permeability and a putative cost - greater exposure to water-soluble toxins.