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Y Dupuis

Publications and source records attributed to Y Dupuis.

At least 55 records · Page 3Linked to original sources
PubMed1977

[Effect of sorbitol on the activity of alkaline phosphatases isolated from different areas of rat small intestine].

To elucidate by which way sorbitol (S) increases Ca absorption, the action of (S) on the alkaline phosphatases (A.P.) isolated from duodenum, jejunum and ileum of the young rat is studied. At pH = 9,8 A. P activation by (S) is the most pronounced with ileal A.P. At each studied pH (greater than or equal to 8) the ability of A. P to phosphorylate (S) is observed constantly. A diffusional system transfer of Ca is proposed involving the intervention of a A. P under the inhibiting control of phosphates. This inhibition would be suppressed by the A. P transphosphorylating action toward (S).

Alkaline Phosphatase↗
PubMed1976

[In-situ intestinal loop study of the carbohydrate and phosphate modulation of calcium absorption].

Absorption of 45Ca from a 10 or 20 mM CaCl2 solution given into rat by injection in jejunal or ileal loops in situ is lowered by sodium phosphate and enhanced by L-xylose. Curves relative to the magnitude of absorption depending of doses of phosphate (5 to 50 mM) or carbohydrate (10 to 150 mM) are similar to those which account for the effect of activators or inhibitors upon the activity of enzymes.

Animals↗
PubMed1976

[Study at the level of the jejunal mucosa of the effects of various carbohydrate compounds on the activity of various enzymes localized in brush borders. Augmentation of phosphatase activity].

On rat jejunum the effects of sorbitol or NaH2PO4 on the activity of various enzymes localized in brush borders was investigated: glycosidases, amino-peptidase, alkaline phosphatase. The activity of phosphatase varies under the influence of these compounds (and others carbohydrates) in the same sense and the same extact than they induce variations of Ca absorption.

Alkaline Phosphatase↗
PubMed1976

[Effect of phosphate upon calcium intestinal absorption (author's transl)].

Adult rats receive 5 to 50 mM CaCl2 solutions in which glycerophosphate or sodium diacid phosphate may be added in variable quantity. These solutions are administered by gavage or in situ ligatured jejunal loop. The inhibition of calcium absorption dependent on simultaneously administered phosphate doses is well characterized: high for the lowest concentration, the inhibiting effect of phosphate doses decreases more and more reaching a limit from which phosphate supplementation has no effect. These observations discarding an intervention of phosphate by calcium insolubilization seem to demonstrate that the control supplied by phosphates on calcium absorption is of enzymatic character. Facts related to the respective effects of calcium and phosphates on the action of alkaline phosphatases lead to discuss a possible intervention of these enzymes upon calcium transfer.

Alkaline Phosphatase↗
PubMed1976

[Calcium absorption by the rat from various milks in relation to their total phosphorus and lactose contents].

The absorption of calcium corresponds to a strictly determined mechanism inhibited by phosphates and activited by carbohydrates. We investigate in what extent the absorption of milk calcium from various species has the same proceeding. 4 months old rats are given orally solutions of CaCl2 alone or in combination with sodium dihydrogen phosphate or lactose or these both compounds. We compare calcium absorption of these solutions to that of milk from woman, cow or sow, or to dilutions of these two latter milks. All these fluids are dosed so that they correspond each other by their respective content in total calcium, total phosphorus and lactose. Each solution contains 45Ca. Blood samples 1,30, 4, 6 and 24 hours after ingestion allow establishing the variations of plasma radioactivity. Rats are sacrified after 24 hours. In certain cases, samples from digestive tube contents and feces provide a coefficient of calcium absorption. The osseous retention is obtained from femur radioactivity. In breif, we may consider that milks from cow and sow provide calcium the absorption of which is settled after their respective content of total phosphorus and lactose. Opposed effects of these inhibitors and activators of calcium absorption compensate so that calcium from these milks is just a little better utilized by adult rat than calcium from an isocalcic solution of CaCl2. Calcium from woman milk, rich in carbohydrates, poor in total phosphorus is better absorbed than that from the two latters, however less than we might expect from its high lactose content. We may wonder that calcium utilization from cow milk is as moderate as that of a solution of CaCl2. But skeleton mineralization which may be fulfilled by milk is made better because of that: it is not chloride but calcium phosphate which ensures this mineralization, a phosphate which alone would impair this mineralization without the compensative role of lactose.

Animals↗
PubMed1975

[Modulation of intestinal absorption of calcium].

1. Absorption of ingested calcium (2 ml of a 10mM CaCl2 solution + 45Ca) by the adult rat was shown to be facilitated by the simultaneous ingestion of an active carbohydrate, L-arabinose. As the carbohydrate concentration is increased from 10 to 200 mM, the adsorption of calcium is maximized at a level corresponding to about twice the control adsorption level. 2. A similar doubling of calcium adsorption is obtained when a 100 mM concentration of any one of a number of other carbohydrates (gluconic acid, mannose, glucosamine, sorbitol, lactose, raffinose, stachyose) is ingested simultaneously with a 10 mM CaCl2 solution. 3. Conversely, the simultaneous ingestion of increasing doses (10 to 100 mM) of phosphate (NaH2PO4) with a 10 mM CaCl2 solution results in decreased 45Ca absorption and retention by the adult rat. 4. The maximum inhibition of calcium adsorption by phosphate is independent of the concentration of the ingested calcium solution (from 5 to 50 mM CaCl2). 5. The simultaneous ingestion of CaCl2 (10 mM) with lactose and sodium phosphate (50 and 10 mM, respectively) shows that the activating effect of lactose upon 45Ca adsorption may be partly dissimulated by the presence of phosphate. 6. These various observations indicate that, within a large concentration range (2 to 50 mM CaCl2), calcium adsorption appears to be a precisely modulated diffusion process. Calcium absorption varies (between minimum and maximum levels) as a function of the state of saturation by the activators (carbohydrates) and inhibitors (phosphate) of the calcium transport system.

Animals↗