Brush-Border metabolism

Intestinal Efflux Processing of Absorbed Drugs and Brush-Border Metabolism... 

First-pass intestinal metabolism. This includes brush border metabolism and intracellular metabolism. The former occurs at the surface of the enterocytes by the enzymes present within the brush border membrane. Furthermore, the brush border activity is generally greater in the proximal small intestine (duodenum jejunum > ileum colon) and involves enzymes such as alkaline phosphatase, sucrase, isomal-tase, and a considerable number of peptidases. ... 

Potential enzymes involved in anthocyanin metabolism — The lactase phlorizin hydrolase (LPH EC 3.2.1.108) present only in the small intestine on the outside of the brush border membrane and the cytosolic P-glucosidase (CBG EC 3.2.1.1) found in many tissues, particularly in liver, can catalyze the deglycosylation (or hydrolysis) of polyphenols. LPH may play a major role in polyphenol metabolism... 

AC ADME ANS AUC BA/BE BBB BBM BBLM BCS BLM BSA CE CHO CMC CPC CPZ CTAB CV DA DOPC DPPC DPPH aminocoumarin absorption, distribution, metabolism, excretion anilinonaphthalenesulfonic acid area under the curve bioavailability-bioequivalence blood-brain barrier brush-border membrane brush-border lipid membrane biopharmaceutics classification system black lipid membrane bovine serum albumin capillary electrophoresis caroboxaldehyde critical micelle concentration centrifugal partition chromatography chlorpromazine cetyltrimethylammonium bromide cyclic votammetry dodecylcarboxylic acid dioleylphosphatidylcholine dipalmitoylphosphatidylcholine diphenylpicrylhydrazyl... 

It should provide the framework to accommodate development of other reaction schemes including metabolism at the brush border surface of the apical membrane. 

It is contended that the renal slice technique measures primarily basolateral uptake of substrates or nephrotoxins, based on histological evidence of collapsed tubular lumens. This results in the inaccessibility of brush-border surfaces for reabsorptive transport (Burg and Orloff, 1969 Cohen and Kamm, 1976). This observation limits the ability of this model to accurately reflect reactions to nephrotoxins that occur as the result of brush-border accumulation of an injurious agent. Ultrastructurally, a number of alterations, particularly in the plasma membrane and mitochondrial compartments, have been shown to occur over a 2-h incubation period (Martel-Pelletier et al., 1977). This deterioration in morphology is very likely a consequence of the insufficient diffusion of oxygen, metabolic substrates, and waste products in the innermost regions of the kidney slice (Cohen and Kamm, 1976). Such factors also limit the use of slices in studying renal metabolism and transport functions. 

Fructose is found in honey and fruit and as part of the disaccharide sucrose (common table sugar). Sucrose is hydrolyzed by intestinal brush border sucrase, and the resulting monosaccharides, glucose and fructose, are absorbed into the portal blood. The liver phosphorylates frurtose and cleaves it into glyceraldehyde and DHAP. Smaller amounts are metabolized in renal proximal tubules. The pathway is shown in Figure 1-12-7 important enzymes to remember are ... 

Peptides, when administered orally, are susceptible to degradation in the stomach by gastric enzymes and the proteinases of the pancreas and brush border of the small intestine. Their lifetimes in the plasma are often short due to rapid proteolysis and other metabolic processes. Early efforts were made to improve the resistance of renin inhibitors to hydrolysis in vivo by the use of blocking groups at the Eland C-terminii [39] and replacement of susceptible peptide bonds other than the renin cleavage site. Studies of SAR have shown that various N- and C-terminal groups, some based on the morpholine nucleus and derivatives of it, have a favorable effect on the duration of inhibition in the... 

Langguth, P., et al. 1994. Metabolism and transport of the pentapeptide metkephamid by brush-border membrane vesicles of rat intestine. J Pharm Pharmacol 46 34. 

The efflux of liver GSH and metabolism of the resulting plasma GSH and GSSG appears to help ensure a continuous supply of plasma cysteine. Interorgan GSH has a half-life of 1-2 min, with the brush border membrane of the kidneys providing... 

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