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Biomedical subjects

G Esposito

Publications and source records attributed to G Esposito.

At least 289 records · Page 16Linked to original sources
PubMed1981

Hyperglycemia and net transintestinal glucose and sodium transport in the rat.

Hyperglycemia produced by intravenous infusion of glucose cause, in the everted jejunum of rat, an increase of net transintestinal transport of glucose, Na and water without modifying their cell concentration. The concentration of glucose in the fluid pouring out at the serosal side is higher than the calculated intracellular concentration, especially in the experiments in which the serosal compartment is initially empty. This fact could be explained by the possible existence of an active extrusion mechanism in the basolateral membrane of the enterocyte.

Animals↗
PubMed1981

Cell bicarbonate and chloride in the jejunum of rat and hamster incubated "in vitro".

1. In jejuna of rat and hamster incubated in vitro, the intracellular bicarbonate concentration has been calculated from direct measurements of pH and pc02 in scraped, diluted and homogenized mucosa Intracellular chloride concentrations have also been determined in the same intestinal tract of both animals. 2. Bicarbonate concentration appears to be much higher in the mucosal cell of the rat than in the hamster. Cell chloride concentration is higher in the mucosal cell of the hamster than in that of the rat. 3. From our data and from those of the literature concerning the profile of the electrical potential difference, we have evaluated the electrical and chemical driving forces acting on the two anions. 4. The results suggest that both bicarbonate and chloride can passively move from the cell across the serosal barrier, but they cannot move passively across the luminal pole of the mucosal cell.

Animals↗
PubMed1980

[Levamisole].

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Animals↗
PubMed1980

Lactate and bicarbonate transport in rat and hamster jejuna incubated in vitro.

The transport of electrolytes into the serosal compartment of everted rat and hamster jejuna, incubated "in vitro" for 1 h, has been evaluated both at 38 degrees C and 28 degrees C. In order to determine the bicarbonate concentration in this compartment, pH and pCO2 were measured. It appears that, under both these experimental conditions, a relationship exists between lactate transport and pCO2 in the serosal side. A diffusion of undissociated lactic acid from the cellular into the serosal compartment is suggested. Oxygen consumption was approximately identical, at 28 degrees C, in both species. If the above assumption is correct, in the rat the anions which follow sodium during its active transport are mainly bicarbonate and chloride, while in the hamster jejunum, sodium is followed by chloride alone.

Animals↗
PubMed1979

Extracellular space determination in rat small intestine by using markers of different molecular weights.

The apparent extracellular space (ECS) of rat jejunum, everted and cannulated "in vitro", has been measured by using extracellular markers of different molecular weights. The markers used were two polyethyleneglycols, 14C and 3H labelled (14C-PEG MW 4000 and 3H-PEG MW 900) and 3H-sucrose. The ECSs for the mucosal and serosal sides have been separately determined throughout the time course, and it has been found that the two spaces are identical when PEG 4000 was used but the serosal ECS is almost the double when using PEG 900. The serosal ECS determined with sucrose is four times as big as the mucosal ECS. It seems reasonable to conclude that the best marker for the measure of total apparent ECS is sucrose, placed in the serosal compartment, taking into account that the mucosal ECS is four times smaller than the serosal one. All the markers used reach equilibrium with ECS, more rapidly in the mucosal than in the serosal ECS. Finally, by comparing cell water and cell Na concentrations, one observes that there is a statistical difference between the results obtained by using PEG 4000 as an extracellular marker and those obtained with sucrose.

Animals↗
PubMed1979

The rat and hamster jejunum during transintestinal transport in vitro.

By using the jejunal tract of rat and hamster intestine, net fluid transintestinal transport in the everted sac incubated in vitro at 28 degrees C and at 38 degrees C has been determined. In the scraped mucosa wet weight/dry weight ratio, cell water, sodium and potassium concentration have been detected in vivo and in vitro, throughout the incubation time, at the two different temperatures. Under all these conditions ATP, ADP and AMP levels have been determined in total intestine and in scraped mucosa. In rat jejunum incubated in vitro at 38 degrees C transintestinal fluid transport continuously decreases during 1-h experiment; in the same time the enterocyte gains sodium, dilutes cell potassium and swells, whereas its energy charge is dramatically reduced. All these parameters are constant in rat jejunum incubated at 28 degrees C and in the hamster incubated both at 28 degrees C and at 38 degrees C throughout the experiment. An inadequate diffusion of oxygen into the enterocyte, could tentatively explain experimental results obtained on rat jejunum at 38 degrees C. Under all tested conditions, energy charge and intracellular potassium are lower in conditions in vitro than in those in vivo; the contrary happens for cell sodium and swelling. The oxygenation of the intestine in vitro, lower than the one in vivo, could explain the different behaviour found in the two experimental conditions.

Adenosine Diphosphate↗
PubMed1977

Water absorption and swelling in the rat small intestine in vitro.

Net mucosal-to-serosal water transport and water retention within the tissue were simultaneously measured in the isolated, everted rat jejunum and ileum along with time. The swelling of the epithelium (delta w/DW-delta w/DW-delta v/DW) precedes the absorption of fluid and then it remains contant throughout the experiment. The water uptake, determined as a weight increase, (delta w/DW) and the net water transport determined as a serosal volume increase (delta v/DW) were higher in Krebs-Ringer-bicarbonate than in a Krebs-Ringer-phosphate medium. In the jejunum glucose markedly stimulated both the tissue retention and net transport of water, but such effect was not seen in the ileum. Replacement of chloride with sulphate in the medium diminishes both water transport and retention, but both were markedly stimulated by the addition of glucose to such medium. As a conclusion it seems that during water transport the epithelial layer swells and the swelling increases when the amount of water transported is increased.

Animals↗
PubMed1976

Energy-rich phosphates and transintestinal transport in rat intestine incubated in vitro at different temperatures.

In the present work, the transported fluid and the tissue content of ATP, ADP and AMP has been evaluated in the jejunum rat intestine which was everted and incubated in vitro both at 28 degrees C and at 38 degrees C for 1 h. The energy-rich phosphates have been measured in the tissue at the beginning and at the end of the experiment as well as in vivo. These determinations have been made in the total intestine and in the scraped mucosa. ATP and ADP content are higher in vivo and lower but constant at 28 degrees C in vitro; on the contrary, at 38 degrees C in vitro, the initial and final content of these adenilic nucleotides are both lower than at 28 degrees C. Under all these conditions the AMP content does not vary appreciably. Wet weight to dry weight ratios ahve been reported for mucosal and submucosal tissues in unincubated and incubated intestines. In some experiments, fluid transport (measured as an actual serosal volume increase) was determined every 20 min during a 1-h incubation. At 28 degrees C, fluid transport is constant throughout the time of the experiment, but at 38 degrees C, there is a progressive decrease of the transported fluid. Fluid transport and ATP content of the intestine seem to be directly related. The transport activity which is lower at 38 degrees C than at 28 degrees C, seems to be due to a low availability of energy-rich phosphates.

Adenine Nucleotides↗
PubMed1976

Effect of ethyl acetate on the transport of sodium and glucose in the hamster small intestine in vitro.

The effect of ethyl acetate on Na+, water and glucose transport, as well as on glucose and electrolyte intracellular concentrations in everted and cannulated sacs of hamster jejunum, have been studied. Ethyl acetate, a substance that easily penetrates and delivers energy to the cell, strongly stimulates net glucose and Na+ transport. The explanation of the experimental results takes into account the possibility of the existence of an active extrusion of glucose at the level of the basolateral membrane of the enterocyte.

Acetates↗