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Biomedical subjects

C Demigne

Publications and source records attributed to C Demigne.

24 records · Page 2Linked to original sources
PubMed1982

Influence of unrefined potato starch on cecal fermentations and volatile fatty acid absorption in rats.

The effect of uncooked potato starch in the diet on cecal fermentation and absorption of volatile fatty acids and on changes in the digestive supply of nutrients were investigated. Dietary potato starch (25%) markedly increased cecal size and the cecal pool of volatile fatty acids. These were maximal in the postabsorptive state, whereas the most acidic cecal pH readings were observed during the late absorptive period. Compared to the basal diet, feeding potato starch did not change arterial concentrations of glucose, lactate or alanine. Nevertheless, blood acetate was increased, whereas plasma triglycerides and cholesterol were reduced. The digestive balance of nutrients was determined by measurements of portal blood flow and arteriovenous differences across the digestive tract: the digestive supply of glucose was maximal during the absorptive period, but was lower in rats fed the potato starch diet. The absorption of volatile fatty acids was strongly increased by feeding potato starch and was maximal in the postabsorptive state, whereas glucose absorption was finished. The volatile fatty acids the constituted the main source of energetic fuels coming from the digestive tract. These results indicate that the effect of potato starch on digestion and metabolism is similar to that of dietary fibers, and that the regular supply of large amounts of volatile fatty acids, particularly during the postabsorptive period, could bring about substantial changes in liver metabolism.

Alanine↗
PubMed1982

Glucose-stimulated insulin secretion in rats with normal plasma calcium levels: effects of calcium deficiency.

Weanling Wistar rats were pair-fed for 9 days a control or a calcium-deficient diet. After a 12-hour fast the rats were injected intraperitoneally with glucose (250 mg/100 g body weight), and blood was collected 15, 30 and 60 minutes after the injection. Before injection, calcium (9.7 +/- 0.2 mg/100 ml), glucose and insulin plasma levels were identical in the control and deficient animals, although calcium-deficient animals showed a small but significant increase in blood plasma magnesium levels. Blood glucose levels were higher in the calcium-deficient rats than in control rats 15 to 30 minutes after the glucose injection (15.4 +/- 1.4 vs. 9.7 +/- 0.4 mM, P less than 0.01, 30 minutes after). Plasma insulin levels were significantly lower 15 minutes after the glucose injection (24 +/- 4 vs. 73 +/- 8 microU/ml; P less than 0.01). Calcium deficiency is therefore associated with a decreased response to the glucose tolerance test in the absence of any change in the blood plasma calcium levels.

Animals↗
PubMed1976

Partition and absorption of valatile fatty acids in the alimentary canal of the rat.

The partition and absorption of volatile fatty acids (VFA) have been studied in the rat using a non purified diet comprising mainly a mixture of cereals and soya-bean meal. 2. The concentration of acetic and lactic acid was compared in non secretory (cul-de-sac) and secretory regions of the stomach. The greatest concentrations of both acids were found in the cul-de-sac region where the pH was highest (pH 5.0). 3. Concentration and absorption of VFA were negligible in the small intestine. 4. High VFA concentrations were found in the caecal contents, while lactic acid concentrations were lower. The volume and concentrations of the caecum contents varied little during the day and decreased rapidly during the first 24 h of fasting. 5. The concentrations of VFA, particularly that of butyric acid, were lower in the proximal colon than in the caecum. Caecumectomy caused a considerable decrease in VFA concentrations in the colon. 6. Arteriovenous differences in VFA and detone bodies were studied for the caecal and colon veins in rats. A close parallel between VFA concentration in the caecal contents and the arteriovenous differences was observed. In rat, ketogenesis was weak in the caecal wall (12 p. 100 of butyric acid absorption) and negligible in the colon wall. VFA are absorbed entirely in ionized form when caecal PH attains 7.5 in fasted rats. Special mechanism for caecal absorption should therefore be considered, perhaps linked with the large sodium transport in the caecum. 7. The relatively high VFA concentrations measured in the portal vein suggested that they are important in the digestive processes.

Animals↗
PubMed1974

Determination of volatile fatty acids in plasma after ethanolic extraction.

1. A new rapid micro-method for measuring plasma volatile fatty acids is described. The volatile fatty acids are extracted from plasma with ethanol in the presence of a known quantity of internal standard (sodium isobutyrate). After evaporation of the ethanolic solution of the sodium salts, the residue is dissolved in a dilute solution of orthophosphoric acid to permit analysis by g.l.c. 2. A technique of g.l.c. analysis is described which permits the separation of all the volatile fatty acids from the other plasma constituents at temperatures below 100 degrees C in 5 min. 3. Steam-distillation techniques are unsatisfactory when the acetic acid concentrations in the plasma are below 0.2mm. Heating of a number of plasma constituents in acid conditions gives rise to acetic acid. 4. The binding of volatile fatty acids to plasma proteins was studied; this binding is negligible for acetic acid, but increases with the length of the fatty acid carbon chain. 5. The limits of use of the method and the physiological implications are discussed.

Animals↗