[Effect of ascorbic acid on the intestinal transport of glycine in chick].

The effect of different doses of ascorbic acid on the absorptive functions of the gut has been investigated in chicks. The study describes evidence for the existence of a H+/glycine symport system in chick intestinal brush border, because in sodium-free conditions acidification of the apical medium with ascorbic acid causes a dose-dependent stimulation of glycine absorption. Under the above circumstances, potassium acts as a non-essential activator of H+-dependence glycine cotransport. Our results also suggest that glycine uptake is stimulated in a lesser degree by inward sodium gradient. Ascorbic acid stimulation of glycine uptake from K+- free sodium abundant media was diminished, when the dietary level of ascorbic acid was increased to 2000 mg in 1 kg of food. This may result from conformational change in the Na(-)-dependent glycine transporter protein that lowers glycine binding site affinity induced by the over-acidification of the gut lumen. In addition, there was a possible competition between sodium-dependent glycine and ascorbic acid transporters for sodium.

[Response of glycine and glycyl-L-valine uptake parametrs across in vitro everted sacs of chicken gut to variations in oxygenation rate and fasting].

Energy-dependent accumulation of glycine and glycyl-L-valine within the small intestinal mucosa in a chicken model of in vitro local oxygenation of the small intestinal preparation was studied. It has been shown that the most effective bilateral oxygenation significantly increase accumulation of glycyl-L-valine in the proximal segment as compared to that under oxygenation only from serosal surface both in the fed and 24-hour fasted chickens, whereas in other segments these differences was less apparent. This may be due to increased H+/ peptide cotransporter expression in the proximal segment. Thus the bilateral oxygenation probably may turn on an additional amount of already existing (but non-functional during serosal oxygenation) H+/ peptide co-transporters. Moreover, low glycine transporter expression may be the reason why supplemental oxygen (bilateral oxygenation) has no effect on glycine accumulation in the distal segment of fed chickens. A 48-hour fasting decreases glycyl-L-valine accumulation in the proximal (and medial) segments, possibly due to progressive decrease in villus height. It is concluded that: a) the accumulation rate of glycine was greater when presented as the glycyl-L-valine than when presented as the equivalent amount of free amino acid; b) the rates of accumulation of glycyl-L-valine are highest in the proximal segment, decrease in the medial segment and are the lowest in the distal segment; c) the serosal oxygenation is less effective than the mucosal and bilateral oxygenation, which markedly stimulates accumulation of nutrients in the intestinal mucosa; d) a 24-hour fasting increases glycyl-L-valine accumulation in the proximal segment only, while glycine uptake was increased in the distal segment.

[Coupling of protease activity and sodium loading with intestinal absorption of amino acids].

Membrane-bound serine proteases to play a certain role in activation of sodium transport in epithelial cells. To were found explain the protease activity and sodium-dependent L-tryptophan transport across chicken small intestine interaction, four experiments were conducted. One hundred chicks were fed diets that contained 0; 0.3; 3 or 6% of supplemental NaCl and were given distillated water ad libitum. Signs of salt toxicity observed were as follows: a decreased body weight, increased heart and kidney weights, formation of secondary lysosomes in enterocytes and lymphocytes. Such chickens were in the state of negative nitrogen balance. Intestinal absorption of L-tryptophan correlated with mucosal protease activity during increased dietary sodium chloride intake. Recent in vitro and in vivo experiments indicate that enterocyte proteases may be of critical importance in activation of sodium-dependent intestinal transporters for L-tryptophan.

[Disorders of zinc transport through the ileal epithelium in vitamin A deficiency and ischemia]. / Narushenie transporta tsinka cherez épitelii podvzdoshnoi kishki pri A-avitaminoze i ishemii.

By means of histochemical revealing of zinc and applying radioactive isotope 65Zn accumulation, absorption and distribution of cations of this metal in the mucous membrane of the iliac intestine have been studied in chicken, normal, at ischemia and at A-avitaminosis. An essential zinc-depositing ability is peculiar to coverings of mucus upon the intestine epithelium, and among intracellular components--to smooth endoplasmic reticulum. A-avitaminosis and especially ischemia result in increasing permeability of the apical part of the external membrane of epitheliocytes, in overloading of the latter with zinc cations, when they are introduced into the intestine, as well as in decreasing transepithelial transport of zinc. The changes mentioned are accompanied with certain disturbances in the barrier function of the intestinal epithelium.

[Effects of natural (zinc, vitamin E) and synthetic (diludin) antioxidants on the intestinal permeability in chicks with vitamin A deficiency]. / Deistvie prirodnykh (tsink, vitamin E) i sinteticheskikh (diludin) antioksidantov na pronitsaemost' kishechnogo bar'era u tsypliat pri nedostatochnosti vitamina A.

The main concern of this work was to examine the relation between altered antioxidant status on the one hand and increase in L-tryptophan absorption in the small intestine in order to bring further information regarding to possible role of vitamin A and zinc to maintaining of intestinal epithelial barrier integrity, on the other hand. In control, only some ideal tight junctions at the tip of the villi were permeable to ZnC1(2), whereas in A-hypovitaminosis permeability increased significantly. Studies demonstrate that an increased L-tryptophan accumulation in the intestinal mucous may result from a free radical damage to the mucous surface with formation of "leaky" junctions in the ilea. The results suggest that the zinc plays a crucial role in stabilizing biomembranes.

[Alternative paths of zinc transepithelial transport in the small intestine]. / Al'ternativnye puti transépitelial'nogo transporta tsinka v tonkoi kishke.

Interrelations among changes in 11-oxycorticosteroids (11-OSC) in blood plasma, catecholamines (CA), and acetylcholinesterase (AChE) activity in nerve fibres of the thymus, as well as qualitative content and proliferative capacity of thymic and blood cells under the effect of the rat recombinant interleukin-1 beta (IL-1 beta) normally and under conditions of hypothalamic-pituitary-adrenocortical depression, were studied. The changes were the most obvious within 15 and 120 min following the IL-1 beta administration: elevation of the 11-OSC, increase in the CA content, and decrease in the AChE activity in thymic nerve fibres. Preliminary administration of dexamethasone prevented the effects.

[The characteristics of amino acid transport in the small intestine of chicks with avitaminosis A]. / Osobennosti transporta aminokislot v tonkoi kishke tsypliat v usloviiakh A-avitaminoza.

An increased amino acid absorption occurred early in chicks in the vitamin A deficiency. This data suggests an effect of the vitamin A upon differentiation of amino acid channels within apical membrane of the absorbing cells.

[Effect of various methods of oxygenation in the isolated small intestine on the tryptophan and glycine accumulation]. / Vliianie razlichnykh sposobov oksigenatsii izolirovannoi tonkoi kishki na intensivnost' akkumuliatsii triptofana i glitsina.

The impact of various oxygenation types of intestinal preparations (mucosal, serosal and bilateral) on the transepithelial transport of amino acids and peptide according to the character of amino acids, their stereoisometry, incubation time, intestinal gradient and other factors, was investigated in fowl. Against-the-gradient-transport of L-tryptophan and glycine was observed at various oxygenation types, and its intensity decreased in the following sequence: bilateral, mucosal, serosal oxygenation. At various oxygenation types, the accumulation of L-tryptophan occurs more efficiently than that of DL-tryptophan and D-tryptophan. Using an in vitro bilateral intestinal oxygenation model system, we have demonstrated the plasma membrane of enterocyte microvilli to be rapidly impaired after oxidative stress. Glycine, but not L-tryptophan, attenuates oxidative injury in brush border membrane and alterations in amino acid transport activity. Overall, our data indicates that in vitro serosal oxygenation of the duodenum markedly improves glycine absorption, possibly involving the basolateral transporters.

[The role of zinc in the iliac absorption of various L-tryptophane forms in chickens]. / Rol' tsinka v protsesse vsasyvaniia razlichnykh form L-triptofana v podvzdoshnoi kishke tsypliat.

Zinc was found to enhance absorption of free and "peptide" L-tryptophan across the chick mucosal brush border. Intestinal absorption of free L-tryptophan can be partially inhibited by excessive amount of zinc. The findings suggest that zinc interacts with free and "peptide" L-tryptophan transports protecting them against degradation.

[Morphofunctional analysis of zinc-accumulating capacity of digestive system organs]. / Morfofunktsional'nyi analiz tsinkdeponiruiushchei sposobnosti organovpishchevaritel'noi sistemy.

The distribution of zinc and related changes have been studied in zinc--loaded chick pancreas, ileum and liver at the ultrastructural level by sulphide--silver method. White Leghorn chicks fed a high zinc diets (50, 500, 1000, 2000 and 4000 mgZn/kg diet) for 6 weeks, were killed at intervals; portions of their organs were fixed for light and electron microscopy; other samples were analyzed for zinc by AA spectrophotometry. A drastic increase of zinc level in chick pancreas fed 2000 mg Zn/kg diet (as ZnCl2) was associated with acinar cell degeneration. Apoptosis was the predominant form of acinar cell deletion. This study provides support for a previously proposed theory that cell injury stimulates passive zinc accumulation.

[Absorption and localization of zinc in the ileum of chicks dependent on provision with vitamin A]. / Vsasyvanie i lokalizatsiia tsinka v podvszdoshnoi kishke tsypliat v zavisimosti ot obespechennosti ikh vitaminom A.

Vitamin A increase the accumulation and transport of zinc in the chick ileal mucosa. Regulating effect of this vitamin on the mentioned processes was already observed in the initial stage zinc uptake in the intestinal mucosa--its storage in the mucus layer. Stimulation of zinc absorption by vitamin A can be related to a specific carrier-vitamin A-dependent zinc-binding protein. Presence of zinc in the smooth endoplasmic reticulum of the enterocyte apical zone suggests the role of this organelle in the cation homeostasis in the cell.

[Experimental research on the antisecretory and antiulcer activity of (+/-) 15 alpha-OH-11-deoxyprostaglandin E1]. / Eksperimental'noe issledovanie antisekretornoi i protivoiazvennoi aktivnosti (+/-) 15 al'fa-OH-11-dezoksiprostaglandina E1.

(+/-) 15 alpha-OH-11-deoxyprostaglandin E1 was found to possess a pronounced antisecretory activity at stimulation of gastric secretion in cats with pentagastrin. In rats the compound exerted the protective effect of cells of the gastric mucosa, especially on indomethacin and stress models of ulcerogenesis. The cytoprotective effect of the compound seemed to be related to its action on secretion of mucus as well as to its stimulation of zinc accumulation in cells that stabilized cell membranes and suppressed the secretory activity of mast cells.