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Paracellular absorption: a bat breaks the mammal paradigm
Enrique Caviedes-Vidal1, William H Karasov, Juan Gabriel Chediack
1Laboratorio de Biología Prof. E. Caviedes Codelia, Facultad de Ciencias Humanas, Universidad Nacional de San Luis-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Luis, Argentina. enrique.caviedes@gmail.com
Plos One
|January 10, 2008
Summary
Bats exhibit enhanced nutrient absorption through passive paracellular pathways, compensating for reduced intestinal tissue. This high intestinal permeability aids nutrient uptake but may reduce selectivity, potentially allowing toxin absorption.
Area of Science:
- Physiology
- Comparative Anatomy
- Biochemistry
Background:
- Bats possess less intestinal tissue than nonflying mammals, advantageous for flight energetics.
- Nutrient absorption occurs via transcellular (transporter-mediated) and paracellular (passive) pathways.
- Understanding nutrient absorption mechanisms is crucial for bat physiology.
Purpose of the Study:
- To investigate the extent of paracellular absorption in bats.
- To determine if bats compensate for reduced intestinal surface area with increased passive absorption.
- To assess the relationship between molecular size and paracellular absorption in bats.
Main Methods:
- Administered inert carbohydrates L-rhamnose and cellobiose (paracellular probes) and 3-O-methyl-D-glucose (dual pathway probe) to Artibeus literatus bats.
- Utilized pharmacokinetic techniques to measure bioavailability of the probes.
- Compared absorption rates with those reported for other mammals.
Main Results:
- Paracellular absorption significantly decreased with increasing molecular mass (rhamnose: 90%, cellobiose: 10%).
- Bat paracellular absorption was substantially higher than in laboratory rats.
- 3-O-methyl-D-glucose absorption was high (96%), indicating significant reliance on both pathways.
- Passive paracellular absorption accounts for over 70% of glucose absorption in bats.
Conclusions:
- Bats exhibit a high reliance on passive, paracellular absorption to compensate for reduced intestinal tissue.
- This enhanced intestinal permeability may facilitate nutrient uptake but could compromise selectivity.
- Further research is needed to evaluate the implications of high intestinal permeability for toxin absorption in bats.
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