MOLECULAR SUPPORT FOR HIGH PARACELLULAR ABSORPTION IN THE INTESTINE OF FLYING MAMMALS

KARASOV, W; BRUN, A.; PRICE, E; GONTERO FOURCADE, M.N; FERNÁNDEZ MARINONE,G.; CRUZ- NETO, AP; CAVIEDES-VIDAL, E

San Diego

Congreso; Society of Integrative and Comparative Biology; 2014

Based on previous work with intact animals, the capacity for paracellular nutrient absorption seems greater in flying mammals than in nonflying mammals, but there has been little testing for the predicted difference in intestinal permeability. We conducted in situ intestinal luminal perfusions on three bats (Artibeus lituratus, Sturnira lilium, Carollia perspicillata) and a rodent (Akodon montensis). Additionally, we assessed paracellular nutrient absorption (fractional absorption = f) in intact animals of one bat (S. lilium) and the rodent. In both approaches, we measured the absorption of a nonmetabolizable D-glucose analog that is absorbed by both paracellular and transporter-mediated mechanisms (3OMD-glucose) as well as a carbohydrate that has no mediated transport (L-arabinose). In intact animals, the fractional absorption of arabinose was complete in the bat (f = 1.2 ± 0.24) and 3x higher than in the rodent (f = 0.35±0.04) whereas 3OMD-glucose absorption was complete in both species (A. montensis: 0.97 ± 0.12, S. lilium: 1.46 ± 0.4). In accord with these results, bats exhibited 2-4 fold higher arabinose clearance than the rodent in intestinal perfusions. All bat species had a higher percent glucose absorption that was estimated to be paracellular (essentially 100%) compared to the rodent (39%). Our findings agree with previous studies showing that the paracellular pathway for nutrient absorption is more prominent in bats relative to nonflying mammals, and this is driven by differences in intestinal permeability to nutrient-sized molecules.