scholarly journals Effects of short-term insulin deficiency on lipogenesis and cholesterol synthesis in rat small intestine and liver in vivo

1985 ◽  
Vol 231 (1) ◽  
pp. 221-223 ◽  
Author(s):  
D H Williamson ◽  
V Ilic ◽  
J Hughes
Keyword(s):  
Small Intestine ◽  
Cholesterol Synthesis ◽  
Physiological Significance ◽  
Oral Glucose ◽  
Rat Small Intestine ◽  
Insulin Deficiency ◽  
Rat Intestine ◽  
Short Term ◽  
Glucose Loading

The rate of lipogenesis in rat intestine increased on oral glucose loading and decreased after induction of acute insulin deficiency with streptozotocin. The latter effects could be partially reversed by administration of insulin. Parallel changes in the rate of lipogenesis were found in liver. In contrast, insulin deficiency did not alter the rate of cholesterol synthesis in intestine, but decreased it in liver. The physiological significance of the regulation of intestinal lipogenesis by insulin is discussed.

Apolipoprotein A-IV synthesis in rat intestine: regulation by dietary triglyceride

1987 ◽  
Vol 252 (5) ◽  
pp. G662-G666 ◽  
Author(s):  
T. F. Apfelbaum ◽  
N. O. Davidson ◽  
R. M. Glickman
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Total Protein ◽  
Mrna Levels ◽  
Rat Small Intestine ◽  
Rat Intestine ◽  
Apolipoprotein A ◽  
Rat Enterocytes

Apolipoprotein A-IV (apoA-IV) synthesis rates were measured in vivo in rat enterocytes by immunoprecipitation after administration of [3H]leucine into in situ loops of jejunum and ileum. Basal apoA-IV synthesis rates (percent total protein synthesis) were significantly higher in jejunal enterocytes (2.05 +/- 0.54%) compared with ileal enterocytes (0.48 +/- 0.32%) from the same fasted animals. After an acute triglyceride bolus, significant and sustained elevations of apoA-IV synthesis rates were seen in both jejunal and ileal enterocytes with maximal effects noted at 4-6 h. Animals fed diets containing 30% wt/wt triglyceride as saturated (SF) or polyunsaturated (UF) fats for 6 wk had similarly increased rates of apoA-IV synthesis in jejunal enterocytes with both SF (3.73 +/- 0.83%) and UF (3.33 +/- 0.64%) but no change in ileal enterocytes. By contrast, animals consuming a fat-free diet for 3 wk had jejunal apoA-IV synthesis rates indistinguishable from basal values (2.40 +/- 0.45%). Translatable intestinal mRNA levels for pre-apoA-IV after triglyceride increased in parallel to synthesis rates with a 50% increase in jejunum and a 350% increase in ileum observed at 4-6 h. These results suggest that apoA-IV synthesis by rat small intestine increases in response to acute and chronic dietary triglyceride, is maintained in the absence of dietary triglyceride, and may be under pretranslational control.

Release of Dipeptide Hydrolase Activities from Rat Small Intestine Perfused in Vitro and in Vivo

1979 ◽  
Vol 57 (6) ◽  
pp. 529-534 ◽  
Author(s):  
M. L. G. Gardner ◽  
Jane A. Plumb
Keyword(s):  
Small Intestine ◽  
Physiological Significance ◽  
Peptide Transport ◽  
Rat Small Intestine ◽  
Experimental Procedure ◽  
Specific Process ◽  
Whole Cells ◽  
Anaesthetized Rats

1. Hydrolase activities against three dipeptides were measured in mucosal cytoplasm in unperfused intestines and in mucosal cytoplasm, luminal effluents and serosal secretions after perfusion in vitro and in vivo for 1 h. Intestines in vitro were prepared both from anaesthetized rats and from freshly killed rats. 2. Only 0·6–1·9% of the initial cytoplasmic activity was recovered in the luminal effluent when intestines in vitro were prepared from anaesthetized rats. Recoveries in luminal effluents were similar (1·3–3·3%) during perfusion in vivo. 3. Losses of dipeptidases into the luminal effluent were four to eight times greater when intestines in vitro were prepared from freshly killed animals. 4. Similar losses of dipeptidases into the secretion on to the serosal surface were observed; they too were much greater when intestines were prepared from freshly killed animals. 5. Small losses of mucosal DNA during perfusion were also observed; however, losses of cytoplasmic peptidases were consistently slightly greater. 6. Enzyme loss therefore probably occurs both by sloughing of whole cells and by a more specific process which is greatly influenced by experimental procedure. Caution is necessary in the interpretation of peptide transport experiments in vitro, although the possibility that intraluminal hydrolysis is of physiological significance must not be excluded.

scholarly journals Tryptophan 5-hydroxylase in rat intestine

1973 ◽  
Vol 131 (2) ◽  
pp. 375-380 ◽  
Author(s):  
T. Noguchi ◽  
M. Nishino ◽  
R. Kido
Keyword(s):  
Enzyme Activity ◽  
Small Intestine ◽  
Physiological Significance ◽  
Rat Small Intestine ◽  
Rat Intestine ◽  
Ph Optimum ◽  
Full Activity

Tryptophan 5-hydroxylase was partially purified from rat small intestine and characterized. The enzyme activity was mainly localized in the distal one-fourth of the small intestine. The enzyme required Fe2+, 2-amino-4-hydroxy-6,7-dimethyl-5,6,7,8-tetrahydropteridine and oxygen for full activity. The pH optimum of the reaction was 8.0. The hydroxylation rate of d-tryptophan by the enzyme was one-third that of l-tryptophan. l-Phenylalanine and l-tyrosine could not serve as substrates. The physiological significance of the enzyme is discussed.

scholarly journals Absorption of lactulose from mammalian gastrointestinal tract

1979 ◽  
Vol 41 (1) ◽  
pp. 47-51 ◽  
Author(s):  
D. F. Evered ◽  
F. Sadoogh-Abasian
Keyword(s):  
Small Intestine ◽  
Calcium Ions ◽  
Clinical Evidence ◽  
Buccal Cavity ◽  
Rat Small Intestine ◽  
Sodium Ions ◽  
Mode Of Transport ◽  
Poor Absorption

1. The disaccharide lactulose (galactosyl-β-1,4-fructose) was poorly absorbed from rat small intestine in vitro and human mouth in vivo.2. These results confirm indirect clinical evidence of poor absorption from the intestine.3. The presence of calcium ions, or absence of sodium ions, had no effect on lactulose absorption from the buccal cavity.4. The presence of ouabain, or absence of Na+, did not decrease the absorption of lactulose from small intestine.5. It is thought that the mode of transport, in both instances, is by passive diffusion with the concentration gradient.

The Influence of Pregnancy and Lactation on the Morphology and Absorptive Capacity of the Rat Small Intestine

1970 ◽  
Vol 38 (3) ◽  
pp. 287-295 ◽  
Author(s):  
I. L. Craft
Keyword(s):  
Small Intestine ◽  
Surface Area ◽  
Absorptive Capacity ◽  
Dry Weight ◽  
Total Weight ◽  
Rat Small Intestine ◽  
Pregnancy And Lactation ◽  
In Pregnancy

1. A study of the length, total weight and weight per cm of the small intestine of virgin, pregnant and lactating rats has provided evidence for an increase in intestinal surface area in pregnancy and lactation. 2. Because of such alterations in morphology of the gut the absorption,in vivo, of the substrates studied, glucose and glycine, has been expressed in terms of amount transferred per loop and also per g dry weight of intestine. 3. Using these parameters the results show that pregnancy does not alter the ability of the upper jejunum to absorb glucose and glycine. In lactation there is a significant decrease in the transfer of these substances when expressed per g dry weight of intestine, but not in absolute terms.

scholarly journals Absorption of two proline containing peptides by rat small intestine in vivo.

1975 ◽  
Vol 248 (1) ◽  
pp. 143-149 ◽  
Author(s):  
A E Lane ◽  
D B Silk ◽  
M L Clark
Keyword(s):  
Small Intestine ◽  
Rat Small Intestine
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