Intestinal passive absorption of water-soluble compounds by sparrows: effect of molecular size and luminal nutrients

Chediack, Juan G.; Caviedes‐Vidal, Enrique; Fasulo, Verónica; Yamı́n, Lázaro J.; Karasov, William H.

doi:10.1007/s00360-002-0314-8

Cited by 42 publications

(29 citation statements)

References 60 publications

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“…Intestinal paracellular absorption in nonflying mammals and birds appears to be qualitatively similar in regards to molecular size selectivity, as characterized using a series of nonelectrolyte water-soluble probes that differ in molecular dimension (80, 199) and in charge selectivity as characterized using relatively inert charged peptides (81, 205). Quantitatively, paracellular absorption is at least twice greater in small birds (< 400g) than in nonflying mammals (Fig.…”

Section: Absorptionmentioning

confidence: 99%

Comparative Digestive Physiology

Karasov

Douglas

2013

Comprehensive Physiology

242

216

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In vertebrates and invertebrates, morphological and functional features of gastrointestinal (GI) tracts generally reflect food chemistry, such as content of carbohydrates, proteins, fats, and material(s) refractory to rapid digestion (e.g., cellulose). The expression of digestive enzymes and nutrient transporters approximately matches the dietary load of their respective substrates, with relatively modest excess capacity. Mechanisms explaining differences in hydrolase activity between populations and species include gene copy number variations and single-nucleotide polymorphisms. Transcriptional and posttranscriptional adjustments mediate phenotypic changes in the expression of hydrolases and transporters in response to dietary signals. Many species respond to higher food intake by flexibly increasing digestive compartment size. Fermentative processes by symbiotic microorganisms are important for cellulose degradation but are relatively slow, so animals that rely on those processes typically possess special enlarged compartment(s) to maintain a microbiota and other GI structures that slow digesta flow. The taxon richness of the gut microbiota, usually identified by 16S rRNA gene sequencing, is typically an order of magnitude greater in vertebrates than invertebrates, and the interspecific variation in microbial composition is strongly influenced by diet. Many of the nutrient transporters are orthologous across different animal phyla, though functional details may vary (e.g., glucose and amino acid transport with K+ rather than Na+ as a counter ion). Paracellular absorption is important in many birds. Natural toxins are ubiquitous in foods and may influence key features such as digesta transit, enzymatic breakdown, microbial fermentation, and absorption

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Section: Absorptionmentioning

confidence: 99%

Comparative Digestive Physiology

Karasov

Douglas

2013

Comprehensive Physiology

242

216

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“…In both studies, and as seen in most other similar studies, fractional absorption declines with increasing size of the inert probe, and absorption increases when coincident with active transport of the D-glucose analogue. Data for sparrows are from Chediack et al (2003), and the data for rats are from Lavin et al (2004) and Lavin (2007). Values ares means^S.E.M.…”

Section: Laboratory Ratsmentioning

confidence: 99%

“…Similar conclusions have been drawn for dogs (Lane et al, 1999) and humans (Fine et al, 1993), but once again birds appear Lavin, 2007). Data for humans were drawn from eight studies cited by Chediack et al (2003), to which data were added from 16 other studies (Bjarnason et al, 1994;Brunetto et al, 1990;Cobden et al, 1985;Erikson & Epsten, 1988;Farhadi et al, 2003;Fleming et al, 1990Fleming et al, , 1993Generoso et al, 2003;Menzies, 1974Menzies, , 1984Menzies et al, 1983Menzies et al, ,1990Menzies et al, , 1999Noone et al, 1986;Saweirs et al, 1985;Wheeler, Menzies & Creamer, 1978). Data for rats were drawn from three studies cited by Chediack et al (2003), to which data were added from four other studies (Martin et al, 2003;Pappenheimer et al, 1994;Sigalet et al, 1996;2000).…”

Section: Laboratory Ratsmentioning

confidence: 99%

“…Data for humans were drawn from eight studies cited by Chediack et al (2003), to which data were added from 16 other studies (Bjarnason et al, 1994;Brunetto et al, 1990;Cobden et al, 1985;Erikson & Epsten, 1988;Farhadi et al, 2003;Fleming et al, 1990Fleming et al, , 1993Generoso et al, 2003;Menzies, 1974Menzies, , 1984Menzies et al, 1983Menzies et al, ,1990Menzies et al, , 1999Noone et al, 1986;Saweirs et al, 1985;Wheeler, Menzies & Creamer, 1978). Data for rats were drawn from three studies cited by Chediack et al (2003), to which data were added from four other studies (Martin et al, 2003;Pappenheimer et al, 1994;Sigalet et al, 1996;2000). Data for other mammalian species include those for mouse (Pappenheimer, 1990), rabbit (Bijlsma et al, 1995;Pappenheimer, 1990), guinea pig (Bijlsma et al, 1995;Delahunty & Hollander, 1987), cat (Bijlsma et al, 1995), dog (Sørensen et al, 1993) and hamster (Delahunty & Hollander, 1987).…”

Section: Laboratory Ratsmentioning

confidence: 99%

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The integration of digestion and osmoregulation in the avian gut

2009

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We review digestion and osmoregulation in the avian gut, with an emphasis on the ways these different functions might interact to support or constrain each other and the ways they support the functioning of the whole animal in its natural environment. Differences between birds and other vertebrates are highlighted because these differences may make birds excellent models for study and may suggest interesting directions for future research. At a given body size birds, compared with mammals, tend to eat more food but have less small intestine and retain food in their gastrointestinal tract (GIT) for shorter periods of time, despite generally higher mass-specific energy demands. On most foods, however, they are not less efficient at digestion, which begs the question how they compensate. Intestinal tissue-specific rates of enzymatic breakdown of substrates and rates of active transport do not appear higher in birds than in mammals, nor is there a demonstrated difference in the extent to which those rates can be modulated during acclimation to different feeding regimes (e.g. diet, relative intake level). One compensation appears to be more extensive reliance on passive nutrient absorption by the paracellular pathway, because the avian species studied so far exceed the mammalian species by a factor of at least two- to threefold in this regard. Undigested residues reach the hindgut, but there is little evidence that most wild birds recover microbial metabolites of nutritional significance (essential amino acids and vitamins) by re-ingestion of faeces, in contrast to many hindgut fermenting mammals and possibly poultry. In birds, there is some evidence for hindgut capacity to breakdown either microbial protein or protein that escapes the small intestine intact, freeing up essential amino acids, and there is considerable evidence for an amino acid absorptive capacity in the hindgut of both avian and mammalian hindgut fermenters. Birds, unlike mammals, do not excrete hyperosmotic urine (i.e. more than five times plasma osmotic concentration). Urine is mixed with digesta rather than directly eliminated, and so the avian gut plays a relatively more important role in water and salt regulation than in mammals. Responses to dehydration and high- and low-salt loads are reviewed. Intestinal absorption of ingested water is modulated to help achieve water balance in one species studied (a nectar-feeding sunbird), the first demonstration of this in any terrestrial vertebrate. In many wild avian species the size and digestive capacity of the GIT is increased or decreased by as much as 50% in response to nutritional challenges such as hyperphagia, food restriction or fasting. The coincident impacts of these changes on osmoregulatory or immune function of the gut are poorly understood.

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“…Paracellular absorption was higher in bats than in rodents for both the probe molecules l ‐arabinose (Figure ) and l ‐rhamnose (Table S8). Researchers hypothesize that paracellular absorption might occur via both a higher capacity “pore” pathway and a very low capacity “leak” pathway (Van Itallie et al, ; Zihni, Mills, Matter, & Balda, ), and paracellular absorption generally declines with increasing molecular size due to size discrimination of the pathway, as predicted by pore theory (Chediack, Caviedes‐Vidal, Fasulo, Yamin, & Karasov, ). Hence, as expected, fractional absorption ( f ) of the smaller‐sized l ‐arabinose (molecular radius ~3.1 å) was greater than the larger‐sized l ‐rhamnose (~3.7 å).…”

Section: Discussionmentioning

confidence: 99%

Morphological bases for intestinal paracellular absorption in bats and rodents

Brun

Marinone

Price

et al. 2019

Journal of Morphology

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Flying mammals present unique intestinal adaptations, such as lower intestinal surface area than nonflying mammals, and they compensate for this with higher paracellular absorption of glucose. There is no consensus about the mechanistic bases for this physiological phenomenon. The surface area of the small intestine is a key determinant of the absorptive capacity by both the transcellular and the paracellular pathways; thus, information about intestinal surface area and microanatomical structure can help explain differences among species in absorptive capacity. In order to elucidate a possible mechanism for the high paracellular nutrient absorption in bats, we performed a comparative analysis of intestinal villi architecture and enterocyte size and number in microchiropterans and rodents.We collected data from intestines of six bat species and five rodent species using hematoxylin and eosin staining and histological measurements. For the analysis we added measurements from published studies employing similar methodology, making in total a comparison of nine species each of rodents and bats. Bats presented shorter intestines than rodents. After correction for body size differences, bats had~41% less nominal surface area (NSA) than rodents. Villous enhancement of surface area (SEF) was~64% greater in bats than in rodents, mainly because of longer villi and a greater density of villi in bat intestines. Both taxa exhibited similar enterocyte diameter. Bats exceeded rodents by~103% in enterocyte density per cm 2 NSA, but they do not significantly differ in total number of enterocytes per whole animal. In addition, there is a correlation between SEF and clearance per cm 2 NSA of L-arabinose, a nonactively transported paracellular probe. We infer that an increased enterocyte density per cm 2 NSA corresponds to increased density of tight junctions per cm 2 NSA, which provides a partial mechanistic explanation for understanding the high paracellular absorption observed in bats compared to nonflying mammals. K E Y W O R D Sbats, enterocytes, nutrient absorption, rodents, small intestine surface area

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Intestinal passive absorption of water-soluble compounds by sparrows: effect of molecular size and luminal nutrients

Cited by 42 publications

References 60 publications

Comparative Digestive Physiology

Comparative Digestive Physiology

The integration of digestion and osmoregulation in the avian gut

Morphological bases for intestinal paracellular absorption in bats and rodents

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