M. J. Delgado

Folate absorption in the jejunum of chronic ethanol-fed rats : In vivo studies

This study sought to determine the intestinal in vivo absorption of folic acid and methyltetrahydrofolate (MTHF) by jejunum surface at different times, after 20 weeks of 30% ethanol ingestion. The absorption results were compared with the data of control rats. In general after ethanol treatment jejunal folic acid absorption was higher than in control rats. When the folic acid concentrations in the perfusion medium were 0.5 microM an increase at later times in ethanol-fed rats was found. At 1 microM the folic acid absorption values were significantly higher at the earlier time. When the concentration assayed was 2.5 microM, significant modifications were only seen at 30 min. Results of MTHF absorption by jejunum of ethanol-fed rats were similar to absorption values of control rats. No significant differences between both groups were found. The results obtained in the present work suggested a different absorptive behavior of both substrates and a different effect of ethanol on folic acid and MTHF absorption in the jejunum.

Comparative Effects of Intestinal Absorption of Folic Acid and Methyltetrahydrofolic Acid in Chronic Ethanol-Fed-Rats

This study concerns in vivo folic acid and methyltetrahydrofolic acid (MTHF) absorption by the whole intestinal surface after 20 weeks of 30% ethanol ingestion in drinking water. The results were compared with control rats fed ad libitum. The total intestinal serosal areas were similar in ethanol-fed and control rats. Significant increases in intestinal length, and decreases in tissue wet and dry weights were found in ethanol-fed rats. Serum folic acid concentrations were significantly less in the animals which had ingested ethanol than in the control rats. Intestinal folic acid absorption was significantly increased at lower substrate concentrations (0.5 and 1 microM), while no difference was observed at 2.5 microM in the ethanol-fed rats. Folic acid absorption relative to tissue wet weight showed significant increases at all tested concentrations in the ethanol-fed rats. Intestinal MTHF absorption showed no significant changes at 0.5 microM MTHF concentration, and an increase was observed in the absorption values at 1 and 2.5 microM concentrations in the ethanol-fed rats. When expressed as tissue wet weight, MTHF absorption values in ethanol-fed rats increased at 1 and 2.5 microM but did not differ at 0.5 microM substrate concentrations. The above results indicate compensatory responses in the folic acid and MTHF intestinal absorption after chronic ethanol ingestion. These effects are observed when the whole intestinal surface is evaluated.

Effect of chronic ethanol on D-galactose absorption by the rat whole intestinal surface

The in vivo absorption of D-galactose by rat whole intestinal surface after 4 weeks of 30% ethanol ingestion in drinking water has been studied, and the results were compared with ad lib-fed control rats. The total serosal intestinal area was determined by integration obtaining similar values between control and alcohol-treated groups. In the caecum surface of ethanol-fed rats slight but not significant increases were found, while the jejunum area decreased with respect to control rats. Total galactose absorption during 10 min of perfusion was slightly increased in ethanol-fed rats but these results were not significant with the substrate concentrations tested. When absorption data were referred to serosal surface, the absorption/cm2 values in ethanol-fed rats were increased at the studied galactose concentrations although these results were only statistically significant at 10 mM. In conclusion, the present data indicates a slight increase in D-galactose absorptive capacity by the whole intestine in ethanol-fed rats which suggest that the tissue traditionally not evaluated such as caecum and colon could modify the functional response to the absorption nutrients.

Comparative effect of distal and proximal intestinal resection and bypass on the rat exocrine pancreas

SummaryWe studied the effects of small-bowel resection and bypass on pancreatic function in rats subjected to a 50% distal resection (DR), a 50% proximal resection (PR), a 50% jejunal bypass (BP) or an intestinal transection (SH) (controls). Duodenal contents were collected after cannulation (under basal conditions). Afterwards, an in vivo duodenal perfusion was made using a glucosaline solution and perfusate was collected for 1 h. Following this, a cholecystokinin (CCK) solution was injected into the jugular vein (1 U/kg body wt.) and perfusion continued for another 1 h. Basal duodenal volume only increased in rats with a PR, and no significant changes occurred in protein content. In basal conditions, no decreases in amylase, lipase, trypsin, or chymotrypsin activities after DR, PR or BP were detected. When animals were subjected to a perfusion and CCK stimulation, no significant changes occurred in animals with BP; the volume was maintained in rats with PR and DR but a decrease in protein and enzymatic contents was found. We concluded that, in basal conditions, the lack (resections) or exclusion (BP) of 50% of the small bowel does not negatively affect the digestive function. When however, a sustained activity is required, the extirpation of intestinal surface provokes a fall in enzymatic activities and is not modified if only the intestinal transit is suppressed, as occurs in the cases of BP.

D-galactose absorption for the whole intestinal surface after different types of resection and bypass

In vivo D-galactose absorption by the whole intestine between duodenum and rectum was studied in rats 1 month after sham operation, 50% proximal resection, intestinal bypass, or 50% distal resection. The total serosal areas were evaluated by means of an integrative method, obtaining reduced surfaces in resected or bypassed animals as compared with controls. The rate of D-galactose absorption, measured within 10 min, increased after proximal resection and bypass and diminished after distal resection, although the level was similar to that of controls at higher substrate concentrations. When expressed as serosal area, results in proximal and bypassed animals were higher than in controls, without differences (at lower galactose concentrations), and increased (at 25 mM), after distal resection. The total absorptive capacity related to wet and dry weight showed no differences in proximal and bypassed groups and a decrease after distal resection. The above results confirm a good level of recuperation when proximal intestinal surface is excluded. In case of ileal extirpation, a smaller compensatory response was found, which would be compensated for by a high substrate concentration in the intestinal lumen.

Changes in lipid parameters after intestinal resection or bypass in the rat.

Intestinal resection, bypass and adaptative postoperative mechanisms developed as a consequence of that surgery, are considered good methods for improving knowledge of gastrointestinal physiology as well as possible effects that the intestine could have on the general metabolism. 50% jejunoileal bypass (BP), 50% proximal (PR) and distal (DR) intestinal resections were performed on rats to compare the influence of resected intestinal segments or bypassed loop localization could exert on different serum lipid parameters. One month after surgery significant increases in total serum cholesterol and cholesterol esters were found. There was no change in free cholesterol. A decrease in triglyceride was observed after distal and proximal resection but no changes after bypass. The cholesterol/phospholipid ratio was increased after resection and after bypass. It has been suggested that the changes in lipid metabolism produced after resections and bypass depend mainly on the loss of absorptive surface rather than on the position of the resected segment. The bypass loop may itself still exert some influence on lipoprotein metabolism, mainly on high density lipoprotein-cholesterol.