Effects of sugars, amino acids and inhibitors on electrolyte transport across hen colon at different sodium chloride intakes.

Lind, Jonas Krog; Munck, B. G.; Olsen, Ole H.; Skadhauge, Erik

doi:10.1113/jphysiol.1980.sp013365

Cited by 54 publications

(14 citation statements)

References 23 publications

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“…From the reduced response of the I.c to leucine and the lack of response to lysine and galactose we speculated (Lind, Munck, Olsen & Skadhauge, 1980) that in the colon of the low Na hen the mechanism for leucine transport has been attenuated and those for lysine and galactose transport abolished. For leucine the data of Fig.…”

Section: Resultsmentioning

confidence: 99%

Effects of dietary intake of sodium chloride on sugar and amino acid transport across isolated hen colon

Lind

Munck

Olsen

1980

The Journal of Physiology

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SUMMARY1. Using the isolated mucosa from the colon ofthe adult hen, transport of galactose, leucine and lysine was studied through measurements of influx across the brushborder membrane, unidirectional transmucosal fluxes, and of steady-state mucosal uptake.2. In hens maintained on a NaCl rich diet influx of galactose, leucine and lysine were saturable processes with well defined values for Jmax and Kt. All three substances were actively transported across the epithelium and accumulated in the mucosal tissues to steady-state concentrations several times higher than in the incubation media.3. In hens maintained on a NaCl poor diet the Kt of the leucine influx was markedly increased and the Jmax moderately decreased, while the epithelium maintained the capability of active transepithelial transport and of establishing a steady-state tissue/medium distribution ratio well above 1. Galactose and lysine could no longer be actively transported and in the steady state their tissue concentrations did not exceed those of the medium.4. It is proposed that in the low NaCl colon the processes of galactose and lysine cotransport with Na are abolished and that the transport of galactose proceeds via a phloretin sensitive system like that described for the enterocyte of the chicken small intestine.5. In the high NaCl colon 1 mM-leucine increases the mucosa to serosa flux of lysine by a factor 2-8 without affecting the serosa to mucosa flux or the steady-state mucosal accumulation of lysine. In the low NaCl colon 1 mM-leucine induces active transepithelial transport of lysine. Assuming that the active transport of leucine is secondary to the transport of Na, leucine-induced active transport of lysine is described as a tertiary active transport.6. In the high NaCl colon the mucosa to serosa flux and the steady-state mucosal accumulation of leucine were inhibited by galactose which had no effect on leucine influx across the brush-border membrane. Leucine did not affect any of the parameters of galactose transport.

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Section: Resultsmentioning

confidence: 99%

Effects of dietary intake of sodium chloride on sugar and amino acid transport across isolated hen colon

Lind

Munck

Olsen

1980

The Journal of Physiology

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Section: Methodsmentioning

confidence: 99%

“…In addition to the ions recorded in Table 1 both solutions contained glucose, 15 mmol/l; MgSO4, 1 mmol/l, and Ca, 2 mmol/l. Glucose was added, since it is necessary in order to obtain maximal rates of NaCl absorption in the colon of the fowl (Lind, Munck, Olsen & Skadhauge, 1980). The animal was subsequently killed by intravenous injection of KCl 3 mol/l and the coprodeumrectum segment removed for determination of the serosal surface area by planimetry.…”

Section: Methodsmentioning

confidence: 99%

OSMOTIC AND IONIC REGULATION DURING DEHYDRATION IN A LARGE BIRD, THE EMU (DROMAIUS NOVAEHOLLANDIAE): AN IMPORTANT ROLE FOR THE CLOACA‐RECTUM

1985

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SUMMARYThe emu, a large (40 kg) flightless bird, has low water requirements yet it has a limited ability to produce concentrated urine. To clarify the factors involved in excretion and water conservation by the emu the patterns of excretion during water restriction were examined. Additionally, kidney function was studied, as also was the role of the cloaca and rectum in the final modification of excreta. Following water restriction the osmolality of the excreta fluid increased to a maximum level at 6 d of 428 + 39(8) mosmol (mean + S.E.M. (n)), the urine to plasma ratio being 1v35 + 0-12(8). In normally hydrated birds almost all Na and Cl were excreted in the fluid fraction but a third of the K was associated with the solid fraction of the excreta. After water restriction for 9 d the pattern of excretion of K did not change but the majority of Na (79%) and Cl (73%) were excreted in the solid phase, possibly associated with urates. In ureteral urine most of the nitrogen was excreted as uric acid or urates; a large fraction, 36 +4(4)%, was not identified. The glomerular filtration rate (G.F.R.) was 41-3 + 2.2(6) ml/kg. h. This value is low when compared with other birds and may be related to the large size of the emu. The G.F.R. decreased by 30% after 7 d water restriction. The cloaca-rectum appears to play a major role in the modification of excreta. In vivo perfusion studies showed transepithelial net transport rates of water and major electrolytes to be large. Transport of water from an isosmotic solution, 3-36+0 17 ml/kg.h, was approximately 10 times the maximum value reported for birds previously. The Na and Cl transport rates were also comparatively high.

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“…Are there transporters in the host's epithelium to absorb these amino acids? Based on numerous studies in birds (Lerner, Sattelmeyer & Rush, 1975;Lind, Munck & Olsen, 1980a;Lind et al, 1980b;McWilliams, 1999;Moreto et al, 1991;Obst & Diamond, 1989) it seems well established that there is a capacity for carrier-mediated absorption of amino acids in the avian caecum and colon. A number of early studies in mammals indicate the same for adult mammalian hindgut (Ardawi, 1986;Hauge & Krippachne, 1970;James & Smith, 1976;King, Sepulveda & Smith, 1981;Olszewski & Buraczewski, 1978;Robinson, Luisier & Mirkovitch, 1973;Sepulveda & Smith, 1979), although some studies failed to find evidence of active amino acid transport (Binder, 1970;Ilundain & Naftalin, 1981).…”

Section: Integrated Function In the Avian Gutmentioning

confidence: 99%

“…Colon from birds (domestic fowl and galah Cacatua roseicapilla ) maintained on a low‐NaCl diet has a Na +− absorption capacity similar to coprodeum, particularly an absence of stimulation of Na + transport induced by hexoses or amino acids (Goldstein & Skadhauge, 2000). For a high NaCl intake colonic transport differs remarkably from that of coprodeum: rather than being suppressed, Na + absorption continues at about half the rate observed in coprodeum during NaCl limitation, but only when glucose and amino acids are present in the lumen (Clauss, Dantzler & Skadhauge, 1991; Lind et al , 1980 b ; Rice & Skadhauge, 1982 a ). This transport is not affected by the blocker of apical Na + channels amiloride, which totally suppresses Na + absorption in both coprodeum and colon from NaCl‐depleted birds.…”

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confidence: 99%

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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Effects of sugars, amino acids and inhibitors on electrolyte transport across hen colon at different sodium chloride intakes.

Cited by 54 publications

References 23 publications

Effects of dietary intake of sodium chloride on sugar and amino acid transport across isolated hen colon

Effects of dietary intake of sodium chloride on sugar and amino acid transport across isolated hen colon

OSMOTIC AND IONIC REGULATION DURING DEHYDRATION IN A LARGE BIRD, THE EMU (DROMAIUS NOVAEHOLLANDIAE): AN IMPORTANT ROLE FOR THE CLOACA‐RECTUM

The integration of digestion and osmoregulation in the avian gut

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