Effect of chronic hypo and hypervitaminosis C on the brush border enzymes and the intestinal uptake of glucose and alanine

Summary Brush border sucrase and alkaline phosphatase activities are considerably enhanced in the intestine of ascorbic acid deficient guinea-pigs. Similar increase in the uptake of D-glucose and L-alanine also occurs in chronic vitamin C deficiency. However the permeability of D-glucose and L-alanine in the intestine of animals fed with large doses of vitamin C is severely depressed, with a reduction in the levels of sucrase and alkaline phosphatase activities.     

Effect of chronic alloxan diabetes and insulin administration on intestinal brush border enzymes.

Brush border sucrase and lactase activities are significantly elevated in alloxan-induced chronic diabetes and are restored to control levels after insulin treatment. Alkaline phosphatase and Mg-ATPase levels remain unchanged in diabetes, compared to a control group. Insulin treatment alone to control animals also led to enhanced activities of these enzymes.     

Effect of chronic alloxan diabetes and insulin administration on intestinal brush border enzymes

Summary Brush border sucrase and lactase activities are significantly elevated in alloxan-induced chronic diabetes and are restored to control levels after insulin treatment. Alkaline phosphatase and Mg-ATPase levels remain unchanged in diabetes, compared to a control group. Insulin treatment alone to control animals also led to enhanced activities of these enzymes.     

Role of glucocorticoids on the maturation of brush border enzymes in fetal rat gut endoderm

Heterospecific recombinants between fatal rat intestinal endoderm and chick mesenchyme, and also undissociated fetal rat intestine, were submitted to different hormonal environments. The present study shows that exogenously-supplied dexamethasone in organ culture, like endogenous hormones provided by the adult rat (grafting experiments) led to similar qualitative and quantitative results, i.e., a 9-fold stimulation of maltase and a precocious induction of sucrase activity in comparison with an hormonal conditions.     

Role of glucocorticoids on the maturation of brush border enzymes in fetal rat gut endoderm

Summary Heterospecific recombinants between fetal rat intestinal endoderm and chick mesenchyme, and also undissociated fetal rat intestine, were submitted to different hormonal environments. The present study shows that exogenouslysupplied dexamethasone in organ culture, like endogenous hormones provided by the adult rat (grafting experiments) led to similar qualitative and quantitative results, i.e., a 9-fold stimulation of maltase and a precocious induction of sucrase activity in comparison with anhormonal conditions.Supported by grant CRL 80 70 17 from the INSERM and by the CNRS. This work was presented in part at the XVth EDBO International Embryological Conference.     

Effect of insulin on the glucose uptake of protozoa.

Insulin stimulates the glucose uptake of Tetrahymena pyriformis. This shows the presence of insulin receptors in Tetrahymena, consequently receptors may be present in a level of phylogenesis, where the natural contact between the given hormone and the cell is unnecessary and impossible.     

Cleavage of p-nitroanilides of N-acylated tri- and tetrapeptides by alanine endopeptidase from the brush border membranes of rat enterocytes

The activity of the alanine endopeptidase from the intestinal brush border was studied using chromogenic substrates of the general formula Sc-Ala2-X-pNA. Sc-Y-Z-Ala-pNA and W-Ala3-pNA respectively. Substrates with C-terminal Leu or Nle are hydrolyzed more readily than Ala-analogues. At least one Ala-residue in one of the positions adjacent to the C-terminus is necessary for the enzyme activity. An Na-substituent has no effect on the activity.     

Selective effects of PHA on rat brush border hydrolases along the crypt-villus axis

The mechanism of the toxicity of lectin from Phaseolus vulgaris seeds has been investigated on rat enterocytes. Cell isolation procedures showed a selectivity in the loss of brush border hydrolases; this indicated that the microvilli blebbing was not the only mechanism of action of lectins on rat enterocytes.     

Selective effects of PHA on rat brush border hydrolases along the crypt-villus axis

Summary The mechanism of the toxicity of lectin fromPhaseolus vulgaris seeds has been investigated on rat enterocytes. Cell isolation procedures showed a selectivity in the loss of brush border hydrolases; this indicated that the microvilli blebbing was not the only mechanism of action of lectins on rat enterocytes.     

Effect of mecloqualone on the oxygen and glucose uptake by brain tissue in vitro

Resumen La mecloqualona inhibe in vitro, la respiración de cortes y homogenizados de cerebro, incrementando el consumo de glucosa; este último efecto no se produce cuando al medio de incubación se añaden 100 mM de potasio.     

Effect of Ketamine hydrochloride on oxygen and glucose uptake by brain tissue in vitro

Resumen El clorhidrato de Ketamina (1×10^–3 M y 1×10^–4 M) incrementa el consumo de oxigeno de cortes de cerebro de rata incubados en Krebs-Ringer fosfato conteniendo 5 mM ó 100 mM de potasio. La droga no modifica el consumo de oxigeno de homogeneizado de cerebro total.     

Effect of an antiglucocorticoid (RU-38486) on hydrocortisone induction of maltase-glucosamylase,sucrase-isomaltase and trehalase in brush border membranes of suckling rats

Summary Induction of -glycosidases by hydrocortisone in suckling rats is inhibited by the daily administration of an antiglucocorticoid (RU-38486). Conversely, RU-38486 injected daily in 15-day-old rats for 7 days does not prevent the spontaneous development of -glycosidases.     

Effect of an antiglucocorticoid (RU-38486) on hydrocortisone induction of maltase-glucosamylase, sucrase-isomaltase and trehalase in brush border membranes of suckling rats

Induction of alpha-glycosidases by hydrocortisone in suckling rats is inhibited by the daily administration of an antiglucocorticoid (RU-38486). Conversely, RU-38486 injected daily in 15-day-old rats for 7 days does not prevent the spontaneous development of alpha-glycosidases.     

Effect of steviol and its structural analogues on glucose production and oxygen uptake in rat renal tubules

Summary The effect of several natural products ofStevia rebaudiana on glucose production and oxygen uptake in rat renal cortical tubules was investigated. Steviol, isosteviol and glucosilsteviol decreased glucose production and inhibited oxygen uptake. The sweet principle stevioside, and steviolbioside, however, were without effect on gluconeogenesis and oxygen uptake.     

Effect of steviol and its structural analogues on glucose production and oxygen uptake in rat renal tubules

The effect of several natural products of Stevia rebaudiana on glucose production and oxygen uptake in rat renal cortical tubules was investigated. Steviol, isosteviol and glucosilsteviol decreased glucose production and inhibited oxygen uptake. The sweet principle stevioside, and steviolbioside, however, were without effect on gluconeogenesis and oxygen uptake.     

Effect of riboflavin deficiency on in vivo incorporation of C14 from labelled alanine into liver glycogen

Zusammenfassung Männliche Albino-Ratten, die während 45 Tagen mit Riboflavin-armer Kost ernährt wurden, zeigten erhöhten Glykogengehalt in der Leber, verbunden mit einer gesteigerten Aufnahme von C¹⁴ aus Alanin-1-C¹⁴ im Leberglykogen. Die Befunde lassen auf erhöhte Glykoneogenese in der Leber Riboflavin-armer Ratten schliessen.     

Effect of (+)-catechin on renal and intestinal transport.

The ability of dog renal cortex slices to accumulate beta-methyl-glucoside or glycine is enhanced by the flavonoid (+)-catechin at a concentration of 3.5 mM. This stimulatory effect is apparently due to a decreased rate of efflux of either substrate. On the other hand, the uptake of p-amino-hippuric acid and N1-methyl-nicotinamide is inhibited by (+)-catechin. The drug at the same concentration is without action on amino-acid transport by guinea-pig intestine in vitro.     

Effects of tryptophan and other amino acids on glucose uptake and carbon dioxide output by the insulin-stimulated adipose tissue.

Tryptophan (4-10 mM) reduces the stimulating effect of insulin on glucose uptake, CO2 output and lactate production by adipose tissue. Similar but lesser effects were also obtained with high concentrations of other amino acids.