Uraemic Toxins

Sundqvist

et al. 1990

Intestinal mucosa forms an important barrier towards harmful agents in the intestinal lumen, besides being the site for absorption of nutrients. Little is known about the intestinal permeability properties in chronic uremia. The permeability toward differently sized polyethylene glycols (PEGs; range 326–1,162 Da) was studied in uremic and control rats on high- and low-protein diets. The 24-hour urinary recovery of PEGs was increased in the uremic groups compared to the control groups. The urinary recovery was also increased in the groups on the high-protein diet compared to the corresponding group on the low-protein diet. This study suggests an increased permeability of PEG molecules in the range of 546–1,162 Da in uremic rats and a decreased intestinal permeability after a low-protein diet in both a uremic and nonuremic state. Thus, in chronic renal failure the intestinal barrier is impaired but returns towards normal with low-protein diets.

Section: Discussionmentioning

confidence: 99%

“…The interplay between the mucosal wall and the mi croflora might be of importance for the uremic syn drome, since substances produced by the bacterial flora have been suggested to be involved in the pathogenesis of uremia [13,14].…”

Section: Introductionmentioning

confidence: 99%

Increased Intestinal Permeability to Differently Sized Polyethylene Glycols in Uremic Rats: Effects of Low- and High-Protein Diets

Sundqvist

et al. 1990

“…In uremia a series of endocrine changes occur [27], Furthermore, clinical studies have suggested that there is accumulation of peptides in serum [28,29]. These changes might have effects on enterocyte growth and differentiation including changes in the expression of brush border enzymes.…”

Section: Discussionmentioning

confidence: 99%

Small Intestinal Peptidases and Disaccharidases in Rats with Acute Uremia

Sjöström²,

Norén³

et al. 1991

Acute uremia was induced in rats with temporary clamping of the left renal pedicle and contralateral nephrectomy. Jejunal peptidase activities (aminopeptidase N, dipeptidyl peptidase IV and aminopeptidase A), disaccharidase activities (maltase, sucrase, lactase and trehalase) and morphology were studied. A significant (p < 0.05) increase in aminopeptidase N activity and a positive correlation between aminopeptidase N activity and serum urea was found in the uremic rats. The other peptidase activities showed a slight increase in the uremic rats. A shortening of the microvilli of the small intestinal epithelial cells in the uremic rats was seen by electron microscopy. The disaccharidase activities were unaltered. This study shows the presence of functional alterations in the small intestine in rats with acute uremia. The observations are also compatible with different regulation mechanisms for the brush border peptidases and disaccharidases.

“…The toxic substances, often referred to as 'uremic toxins', are thought to be generated mainly from the metabolism of nitrogen-containing compounds, but some seem to be generated by the bacterial flora of the gut [1][2][3][4]. Treatment with a low-protein diet reduces particularly the gastro intestinal symptoms of uremia, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Uremia is characterized by glomerular insufficiency which causes impaired excretion and thus retention of various toxic substances in body fluids [1]. The toxic substances, often referred to as 'uremic toxins', are thought to be generated mainly from the metabolism of nitrogen-containing compounds, but some seem to be generated by the bacterial flora of the gut [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Urinary Excretion of Differently Sized Polyethylene Glycols after Intravenous Administration in Uremic and Control Rats: Effects of Low- and High-Protein Diets

Magnusson²,

Sundqvist³

et al. 1990

The intestine constitutes a barrier towards potentially harmful agents in the intestinal lumen. Different-sized polyethylene glycols (PEGs; range 326–1,162 Da) have been used to study the intestinal permeability properties in ⁵/₆-nephrectomized rats on either a high- (22%) or low-protein (8%) diet. PEGs were administered intravenously, and the urinary recovery was measured. The 24-hour urinary recovery of PEGs was significantly reduced in the uremic groups. The ratios between different sizes of PEGs, indicating a size-selective escape of molecules from blood, were decreased in the uremic groups. The urinary recovery was in general increased in the control group on the high-protein diet compared to the control group on the low-protein diet. The results provide evidence for an increased permeability of larger PEGs (range 634–1,162 Da) in uremic rats and that the protein content of the diet might affect the permeability properties.