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At least 199 records · Page 11Linked to original sources

PubMed1994

Drug absorption from large intestine: physicochemical factors governing drug absorption.

Profiles of absorption versus drug molecular weight and absorption versus drug lipophilicity were investigated in both the small and large intestines of rats by an in situ loop method. The absorption-molecular weight profiles examined using different-sized polyethylene glycols (PEGs) were different between the small and large intestines; the large-intestinal absorption of PEGs with molecular weights larger than 300 was poor, while PEGs with molecular weights up to 600 were relatively well absorbed in the small intestine. It is suggested that the paracellular route for drug penetration in the large intestine is restricted more than in the small intestine. The absorption-lipophilicity profiles were also examined in various regions (loops of 6 cm) of rat intestine using three acylsalicylic acids, acetyl-, propionyl- and butyrylsalicylic acids. The absorption rates of the acylsalicylic acids were different in the intestinal regions: the jejunum > the ileum > the colon > the rectum. In each region, the absorption rate increased with the drug lipophilicity. However, it was shown that the absorption rates in the small intestine tended to reach a ceiling at the high lipophilicity. To confirm this tendency, the absorption rates of acetaminophen and indomethacin were compared in the four intestinal regions. The absorption rates of highly lipophilic indomethacin were similar in the large and small intestines, while intermediately lipophilic acetaminophen was more rapidly absorbed in the small intestine than in the large intestine. A thicker unstirred water layer adjacent to the small-intestinal mucosa would be one of the factors which cause such varying absorption-lipophilicity profiles.

Animals↗

PubMedDate not supplied

[The effect of regulatory peptides on water absorption in the large intestine of the frog].

Preparation of isolated large intestine of the frog was filled with Ringer's solution diluted with distilled water (1:5) and was placed into the glass with normal Ringer's solution. The preparation was weighed within every 30 min and the osmotic permeability was determined for water of the mucous and serous layers of the intestine. Then one of the peptides was added to Ringer's solution and the experiment continued. It is stated that bombesin, neurotensin, encephalins, substance P, somatostatin, pituitrin are able to change liquid absorption from the large intestine cavity when the concentration of Ringer's solution in the cavity and from its serous surface is the same. Bombesin and neurotensin inhibited while encephalins stimulated liquid absorption and these effects depended on the transport of ions. Liquid absorption by the osmotic gradient decreased using bombesin, substance P and increased using somatostatin. More complex peptide-peptide relations are observed if using pituitrin and other peptides. cAMP is shown to participate in bombesin effects.

Animals↗

PubMed1998

Role of the large intestine in the pathogenesis of diarrhea in weaned pigs.

OBJECTIVE: To determine whether the large intestine may have a role in counterbalancing the loss of fluid from the small intestine of pigs with diarrhea. ANIMALS: 2 groups of pigs (1 from a specific-pathogen-free herd and 1 from a herd with a history of diarrhea). PROCEDURE: At weaning and 4, 7, 11, and 14 days after weaning, the percentage of dry matter in the large intestinal contents, total and individual concentrations and volatile fatty acids in large-intestinal contents and blood, and concentration of aldosterone in the blood were measured. RESULTS: Large intestinal contents of pigs with diarrhea had a lower percentage of dry matter, lower acetate and butyrate concentrations, and higher propionate concentrations than did those of specific-pathogen-free pigs, and blood of pigs with diarrhea also had lower total volatile fatty acids concentration, higher aldosterone concentration, and lower sodium concentration. CLINICAL RELEVANCE: The large intestine has a role in the pathogenesis of diarrhea in weaned pigs.

Aging↗

PubMed1995

[Intramural blood vessel system of the large intestine of domestic ruminants].

The vascular system of the large intestine of 15 cattle, 10 sheep and 5 goats has been examined by means of corrosion vascular casts, histology and electron microscopy. The results are as follows: The course and ramification of the intestinal vessels are identical in the caecum, colon and rectum. Furthermore, as expected, amongst the species studied no substantial differences in the vascular architecture of the large intestinal wall could be determined. The extramural vessels reach the wall of the intestine at the mesenteric margin. Their branches build arterial or venous networks in the tela subserosa, which then divide into branches in the direction of the antimesenteric region. The connections between the blood vessels of the tela subserosa and the tela submucosa as well as the branches to the muscular layers emerge from these networks. In the tela submucosa an arterial and venous system can be found. The obvious vascular arrangement in the submucosa is arranged not only parallel to the stratum circulare of the tunica muscularis but also along the prevailing direction of the lamina muscularis mucosae. From this arrangement both a deep and a superficial submucosal vascular plexus can be denominated. The recurrent branches for the circular muscle layer as well as the afferent and efferent vessels of the mucosa originate from submucosal arteries and veins. The arterioles of the tunica mucosa branch at the level of the basal crypts into a periglandular capillary system running close to the lumen into a subepithelial capillary system. Here the capillaries drain into venules which advance to the region of the intestinal glands and consequently drain into collecting veins in the submucosa. Capillaries of the subepithelial lamina propria mucosae are furnished with continuous or fenestrated endothelial linings as the morphological equivalent of the secretory or resorption processes, respectively. In the walls of the large intestine of the bovine, sheep and goat there are neither arterio-venous anastomoses nor hemodynamic regulatory structures such as sphincters or so-called throttle veins at the points of transition from capillaries to venules. These results are in accord with the findings in the small intestine of domestic ruminants (Hummel 1980).

Animals↗

PubMed1991

Relationship between length and surface area of each segment of the large intestine and the incidence of colorectal cancer.

In investigating the occurrence and clinical characteristics of diseases of the large intestine, particularly tumors, the number, distribution, and incidence of the lesions were compared between segments of the large intestine. If the distribution and incidence of lesions are correlated with the length or surface area of each segment, the incidence of lesions will be the same throughout the large intestine. If the lesions are unrelated to length or surface area, the factors that affect the occurrence of lesions must be determined and will be characteristic for each segment. However, the length and surface area of each segment of the large intestine and the ratios of each to both the total length and surface area of the large intestine are not clear. In this study the length and surface area of each segment of the large intestine were measured and calculated using the barium enema technique, and the incidence rates of cancer per unit length and surface area of each segment were determined and compared.

Barium Sulfate↗

PubMed1955