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  • 1
    Electronic Resource
    Electronic Resource
    The relationship between the functional and structural alterations in the rat small intestine following proximal resection of varying extents (1978)
    Springer
    Research in experimental medicine 173 (1978), S. 41-53 
    Details
    ISSN: 1433-8580
    Keywords: Intestinal resection ; Mucosal morphometry ; Intestinal transport ; Hyperplastic transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The functional and structural characteristics of the ileal remnant of rat intestine were examined four weeks after 45%, 70% or 95% proximal resection. The increase in villus height in the ileal remnant had already reached its maximum after a resection of 45%, whereas a further increment in the length of the crypts occurred after 70% resection. There was an increase in the number of enterocytes per unit length of villus and a rise in the DNA content per unit weight of mucosal scrapings, which testifies to the development of mucosal hyperplasia in this situation. The specific activities of sucrase, measured biochemically, and of nonspecific esterase, determined histochemically, were reduced in proportion to the extent of the resection. Similarly, the uptakes of L-phenylalanine and ofβ-methyl-D-glucoside by intestinal rings in vitro were progressively diminished in the ileal remnant. There was an increase in the rate of disappearance of glucose from a perfused loop in vivo, when expressed in terms of unit intestinal length. Galactose absorption remained unchanged, but when expressed in terms of unit dry tissue, was significantly reduced, in agreement with the diminished transport of both amino-acids and monosaccharides in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851373
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  • 2
    Electronic Resource
    Electronic Resource
    Protection of the intestinal mucosa during ischaemia by intraluminal perfusion (1975)
    Springer
    Research in experimental medicine 166 (1975), S. 183-191 
    Details
    ISSN: 1433-8580
    Keywords: Intestinal ischaemia ; Intestinal transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The function of the intestinal mucosa immediately after one hour's ischaemia was examined by means of tests in vivo and in vitro. During the ischaemia, the intestinal loop was perfused with media of different compositions, in an attempt to assess which provided the best protection of the epithelium from the deleterious effects of the ischaemia. The absorption of water, ions and glucose was then monitored in vivo, and the uptake of phenylalanine and ß-methyl-glucoside by slices of mucosa was determined in vitro. The unprotected mucosa loses all active transport capacity in vitro following one hour's ischaemia, and is the site of a pronounced loss of water and ions into the lumen in vivo. Glucose absorption in vivo is also abolished. If the loop is perfused during the ischaemia with glucose-containing Krebs bicarbonate buffer, much of the transport capacity in vitro is retained; the loss of ions and water is prevented, and glucose absorption in vivo occurs. Perfusion during the ischaemia with other media, such as isotonic mannitol, Krebs bicarbonate buffer, or Ringer-lactate solution, results in a marked protection of the mucosa, in comparison with the unperfused loop, but the effects are not as pronounced as those of the glucose-containing buffer. It is concluded that the act of perfusing the intestine is the most beneficial factor, but that the presence of glucose in the perfusate does afford added protection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851184
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  • 3
    Electronic Resource
    Electronic Resource
    Source of net water and electrolyte loss following intestinal ischaemia (1980)
    Springer
    Research in experimental medicine 176 (1980), S. 263-275 
    Details
    ISSN: 1433-8580
    Keywords: Intestinal ischaemia ; Triton X-100 treatment of intestine ; Intestinal transport functions ; Intestinal secretion ; Enterocyte maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ischaemia of the dog intestine lasting 1 h causes desquamation of the epithelium at the villus tips and congestion in the villus capillaries. The crypt cells are relatively undamaged. These changes are associated with a loss of active transport of organic solutes, determined in vitro, a reduction in mucosal sucrase activity and an abolition of glucose absorption in vivo. A profuse net loss of water and electrolytes into the lumen in vivo develops. The net sodium loss is due primarily to an inhibition of the lumen-blood flux of this ion, the blood-lumen flux being relatively unchanged. In uraemic dogs, the loss of urea into the lumen is the same in control and ischaemic loops, testifying to the lack of change in the unidirectional water flow from blood to lumen. Perfusion of the dog intestine with 1% Triton X-100 leads to morphological changes that have certain similarities with those provoked by ischaemia. Damage was restricted to the villus tips, protection from further alterations apparently being provided by a mucus layer that forms on the mucosal surface; the crypt region remained unchanged. After 10 min exposure, organic solute transport in vitro and glucose absorption in vivo were both reduced but not abolished; sodium and water absorption in vivo were suppressed, but no net secretion occurred. To account for these observations, we have suggested that the normal crypt cell is a secretory element with respect to sodium and water. During maturation, its absorptive properties develop such that the mature enterocyte, possessing both absorptive and secretory mechanisms, is capable of net absorption of sodium. After destruction of the villus tips, net secretion continues in the crypts; if there are insufficient villus cells remaining to ensure reabsorption, a net secretory capacity is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01855846
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  • 4
    Electronic Resource
    Electronic Resource
    La fonction de la muqueuse après une occlusion aiguë de l'intestin grêle du rat (1973)
    Springer
    Research in experimental medicine 160 (1973), S. 321-325 
    Details
    ISSN: 1433-8580
    Keywords: Intestinal occlusion ; Intestinal transport ; Occlusion intestinale ; Transport intestinal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Une occlusion mécanique de l'intestin grêle du rat a été produite 40 cm au-dessus de la valve iléo-caecale. Les animaux ont été sacrifiés le premier, deuxième et troisième jour post-opératoire, et l'état des anses intestinales a été comparé avec celui des anses témoins prélevées chez des rats non-traités. Comme paramètre de la fonction intestinale, nous avons mesuré l'absorption de phénylalanine par le tissu in vitro. Les résultats ont montré que la capacité absorptive de l'acide aminé, surtout en amont de l'occlusion, est abaissée par rapport aux anses témoins, et ceci déjà à partir du premier jour et progressivement jusqu'au troisième jour post-opératoire. En aval de l'occlusion la diminution de l'absorption est moins accentuée. Histologiquement, on observe une déformation des villosités au-dessus de l'occlusion, mais le recouvrement épithélial reste intact.
    Notes: Summary The rat intestine was mechanically obstructed 40 cm above the ileo-cæcal valve. The animals were sacrificed on the first, second and third postoperative day and the state of their intestines was compared with that of control loops taken from sham-operated rats. Intestinal function was determined by measuring the absorption of phenylalanine during incubation of intestinal ringsin vitro. The absorptive capacity was reduced, particularly above the occlusion, the decrease being progressive from the first to the third day. Below the occlusion the reduction was slighter. Histologically, deformation of the villi above the occlusion is observed, but the epithelial layer remains intact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851472
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  • 5
    Electronic Resource
    Electronic Resource
    Differential effects of harmaline and ouabain on intestinal sodium, phenylalanine and β-methyl-glucoside transport (1976)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 295 (1976), S. 231-236 
    Details
    ISSN: 1432-1912
    Keywords: Harmaline ; Quabain ; Intestinal transport ; Dog colon ; Sodium-potassium-ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Harmaline inhibits both the Na+-K+-ATPase activity and the uptake of l-phenylalanine in guinea-pig intestinal mucosa. The latter effect is not a direct consequence of the former, since higher concentrations are needed to inhibit the enzyme than the influx into the mucosa. Furthermore the uptake is still sensitive to harmaline when the Na+-K+-ATPase has been fully inhibited by ouabain. Harmaline can inhibit l-phenylalanine influx at a concentration at which it does not affect intracellular ion concentrations. Ouabain, however, inhibits the uptake of l-phenylalanine only after a 30 min preincubation period, when the intracellular sodium concentration reached the extracellular level. Harmaline also interferes with the influx of β-methyl-d-glucoside in the mucosa of the dog colon. Addition of harmaline at the mucosal face of the tissue suppresses all net transport of sodium and chloride ions and l-phenylalanine across the mucosa. Thus the same mode of action appears to apply in both the guinea-pig ileum and the dog colon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00505091
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of naringenin on the intestinal and renal transport of organic solutes (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 307 (1979), S. 79-89 
    Details
    ISSN: 1432-1912
    Keywords: Flavonoids ; Naringenin ; Intestinal transport ; Renal transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Naringenin (4′,5,7-trihydroxy-flavanone) inhibits the accumulation of glycine, β-methyl-glucoside, p-amino-hippurate and N1-methyl-nicotinamide in dog renal cortex slices. It also inhibits oxygen consumption by this tissue. Since the sensitivity of amino-acid uptake to the drug is less than the sensitivity of oxygen consumption, the inhibition of this transport might be secondary to an effect on intermediary metabolism. The inhibition of PAH uptake occurs at a lower concentration of the drug, and so naringenin may affect this process at the membrane level. Naringenin inhibits the transport of sugars and amino-acids by dog, guinea-pig and rat small intestine. Both steady-state accumulation and initial rates of entry are affected. Amino-acid uptake is depressed both in the presence or absence of sodium ions. The inhibition is reversible provided short contact times are employed. According to kinetic analysis, naringenin appeared to be a fully non-competitive inhibitor of phenylalanine influx. Examination of the unidirectional transmural fluxes of phenylalanine across guinea-pig intestine revealed that only the mucosal-serosal flux was affected, and then only if the flavanone was added to the solution bathing the mucosal face of the tissue. Naringenin does not inhibit mucosal Na+-K+-ATPase, but it does alter the intracellular ion concentrations. Although some of the results can be explained in terms of an effect of naringenin on metabolism, others can not. It is argued that naringenin has a direct action on cell membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00506555
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