scholarly journals The effect of starvation on the control of phosphofructokinase activity in the epithelial cells of the rat small intestine

1983 ◽  
Vol 210 (1) ◽  
pp. 129-135 ◽  
Author(s):  
A Jamal ◽  
G L Kellett
Keyword(s):  
Small Intestine ◽  
Epithelial Cells ◽  
Terminal Ileum ◽  
Specific Activity ◽  
Utilization Rate ◽  
Proximal Jejunum ◽  
Rat Small Intestine ◽  
Humoral Factors ◽  
Specific Activities ◽  
Regulatory Properties

1. The effect of depriving rats of food for 48 h on the specific activity of phosphofructokinase in the epithelial cells of the small intestine and on the regulatory properties of the enzyme displayed in crude (particle-free) mucosal extracts was studied. 2. The specific activity of phosphofructokinase, measured under optimal conditions at pH8, in the mucosa of fed rats showed a negative aboral gradient along the intestine, decreasing from 15.2 +/- 1.2 units (mumol/min)/g wet wt. in the proximal jejunum to 4.6 +/- 1.2 units/g wet wt. in the terminal ileum. 3. After starvation, the gradient was diminished, but not abolished; the diminution in gradient was due almost exclusively to a decrease in the specific activity of phosphofructokinase in the proximal jejunum by about 30%, there being no change in the terminal ileum. 4. In fed rats, the susceptibility of phosphofructokinase to inhibition by ATP, when assayed in crude mucosal extracts under suboptimal conditions, was independent of length along the small intestine; the ratio of the activity observed at pH 7.0 in the presence of 0.5 mM-fructose 6-phosphate and 2.5 mM-ATP to the optimal activity at pH 8, v0.5/V, was 0.36 +/- 0.05 in the proximal jejunum and 0.42 +/- 0.07 in the terminal ileum. 5. After starvation, the susceptibility of phosphofructokinase to inhibition by ATP was increased and was again found to be independent of length along the small intestine: after starvation, v0.5/V was 0.19 +/- 0.04 and 0.20 +/- 0.07 for the proximal jejunum and the terminal ileum respectively. 6. Re-feeding of previously starved rats on a high-carbohydrate diet overnight for 16 h restored both the specific activities of phosphofructokinase and its susceptibility to inhibition by ATP to normal values for fed rats. 7. The data support the idea that the specific activities and the regulatory properties of phosphofructokinase in the epithelial cells of rat small intestine are mediated by distinct humoral factors. 8. The changes in glucose utilization rate of the jejunum when rats are starved can in principle be accounted for by a combination of changes in the specific activity and in the regulatory properties of mucosal phosphofructokinase.

THE EFFECT OF FASTING ON DISACCHARIDASE ACTIVITY IN THE RAT SMALL INTESTINE

PEDIATRICS ◽  
1971 ◽  
Vol 47 (1) ◽  
pp. 65-72
Author(s):  
L. K. McNeill ◽  
J. R. Hamilton
Keyword(s):  
Small Intestine ◽  
Epithelial Cells ◽  
Specific Activity ◽  
Cell Mass ◽  
Free Access ◽  
Lactase Activity ◽  
Childhood Diseases ◽  
Mucosal Protein ◽  
And Function ◽  
Fasted Rats

We assessed intestinal structure, mucosal epithelial kinetics, and disaccharidase activities after fasting. Rats fasted for up to 120 hours were compared with control rats fed ad libitum. All rats had free access to water and all were prevented from ingesting their own stools. Body weight, small intestinal weight and mucosal protein, and maltase and sucrase activity of the total small intestine decreased in fasted rats. Lactase activity did not decrease. Specific activity of lactase actually increased in the jejunum. Assessed after a 96-hour fast, jejunal villi were shortened with less epithelial cells along their length and the rate of migration of those cells along the villi was diminished in the fasted rats compared with control rats. We attribute the decreased total intestinal sucrase and maltase activities to a loss of total epithelial cell mass in the small bowel. An abnormality in the cells of the progenitor zone of the crypts is suggested by the decreased migration rate of mucosal epithelial cells in fasting rats. These factors do not explain our observations completely since lactase activity did not diminish. We postulate that the activity of the "acid" β-galactosidase located in the cytoplasm or lysosomes of the epithelial cells was stimulated by fasting. Our observations are relevant to clinical pediatrics. Undernutrition and fasting my be associated with many childhood diseases and with treatment of disease. In assessing clinical data and advising treatment, the pediatrician should be aware of the potentially harmful effects of starvation on intestinal structure and function.

Transcriptional regulation of intestinal hydrolase biosynthesis during postnatal development in rats

1994 ◽  
Vol 267 (4) ◽  
pp. G584-G594 ◽  
Author(s):  
S. D. Krasinski ◽  
G. Estrada ◽  
K. Y. Yeh ◽  
M. Yeh ◽  
P. G. Traber ◽  
...  
Keyword(s):  
Small Intestine ◽  
Transcriptional Control ◽  
Mrna Levels ◽  
Rat Small Intestine ◽  
Rnase Protection ◽  
Reciprocal Regulation ◽  
Adult Rat ◽  
Microvillus Membrane ◽  
Specific Activities ◽  
Respective Protein

Lactase-phlorizin hydrolase (LPH) and sucrase-isomaltase (SI) are intestine-specific microvillus membrane hydrolases whose specific activities demonstrate reciprocal regulation during development but whose mechanisms of regulation have not been fully defined. To investigate transcriptional control of these two proteins, the rat LPH and SI genes were cloned, and antisense probes for preprocessed mRNAs (pre-mRNAs) were developed from intron sequence. LPH mRNA, as measured by quantitative ribonuclease (RNase) protection assays, was abundant before weaning and decreased two- to fourfold during weaning, whereas SI mRNA was first detected 14 days after birth and increased rapidly to abundant levels by age 28 days. LPH and SI pre-mRNA levels paralleled those of their respective mRNAs. LPH transcriptional rate declined during weaning, whereas that of SI increased during this time as determined by RNase protection assays of pre-mRNAs and nuclear run-on assays. In the adult rat, LPH mRNA was restricted to the jejunum and proximal ileum, whereas SI mRNA was detected throughout the small intestine, a pattern regulated by transcriptional rate as confirmed by nuclear run-on assays. Lactase and sucrase specific activities correlated well with their respective protein and mRNA concentrations in all experiments. We conclude that gene transcription plays a major role in the developmental and horizontal regulation of LPH and SI biosynthesis and that these two genes are regulated differently in rat small intestine.

Intestinal phospholipase A and triglyceride lipase: localization and effect of fasting

1982 ◽  
Vol 242 (2) ◽  
pp. G168-G176 ◽  
Author(s):  
K. M. Shakir ◽  
L. Gabriel ◽  
S. G. Sundaram ◽  
S. Margolis
Keyword(s):  
Small Intestine ◽  
Specific Activity ◽  
Isolated Hepatocytes ◽  
Phospholipase A ◽  
Intestinal Cells ◽  
Enzyme Release ◽  
Rat Small Intestine ◽  
Triglyceride Lipase ◽  
Plasma Hormones ◽  
Fasted Rats

We investigated the distribution of phospholipase A and triglyceride lipase in the rat small intestine and the effects of heparin and hormones on enzyme release. Phospholipase A activity was 10 times higher in the ileum than in the jejunum; triglyceride lipase activity was threefold higher in the jejunum than in the ileum. Activities of both enzymes were much greater in villus than in crypt cells. The specific activity of phospholipase A was highest in microsomes and least in cytosol. The crude nuclei and brush-border fraction contained 40.5% of total phospholipase A activity; mitochondria contained 33.8%; and microsomes, 17.4%. Phospholipase A activity increased significantly in the distal intestinal mucosa in fasted rats compared with controls. Heparin did not increase the release of phospholipase A by isolated intestinal cells or perfused intestinal vasculature. Thus, the small intestine probably does not contribute significantly to the phospholipase A activity of postheparin plasma. Hormones and cAMP, which inhibit the secretion of phospholipase A and triglyceride lipase from isolated hepatocytes, had no effect on the release of either enzyme from intestinal cells.

scholarly journals Studies of dihydroxyacetone phosphate acyltransferase in rat small intestine. Subcellular localization and effect of partially hydrogenated fish oil and clofibrate

1992 ◽  
Vol 282 (2) ◽  
pp. 565-570 ◽  
Author(s):  
B Ruyter ◽  
J S Lund ◽  
M S Thomassen ◽  
E N Christiansen
Keyword(s):  
Small Intestine ◽  
Subcellular Localization ◽  
Fish Oil ◽  
Gradient Centrifugation ◽  
Dihydroxyacetone Phosphate ◽  
Rat Small Intestine ◽  
Specific Activities ◽  
Fold Stimulation ◽  
Effect Of Feeding ◽  
Stimulation Of

The subcellular localization of dihydroxyacetone phosphate acyltransferase (DHAPAT) activity in rat small intestine was investigated by Nycodenz-gradient centrifugation. We found that DHAPAT had a predominant peroxisomal distribution, with a separate enzyme activity located in the microsomal fraction, the same distribution as found in rat liver. The effect of feeding rats on a diet with 20% (w/w) partially hydrogenated fish oil (PHFO) or 0.3% clofibrate on the activity of DHAPAT in rat small intestine and liver was studied. Both 20% PHFO and 0.3% clofibrate gave a 1.8-fold stimulation of the specific activities of DHAPAT in peroxisomes of the small intestine, whereas in the liver 20% PHFO gave a 1.4-fold stimulation and 0.3% clofibrate a 1.6-fold stimulation of the total DHAPAT activities in the postnuclear supernatant. The specific activities of DHAPAT in liver were not affected.

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