Metabolism heterogeneity

The coupling of solute transport in the GI lumen with solute lumenal metabolism (homogeneous reaction) and membrane metabolism (heterogeneous reaction) has been discussed by Sinko et al. [54] and is more generally treated in Cussler s text [55], At the cellular level, solute metabolism can occur at the mucosal membrane, in the enterocyte cytosol, and in the endoplasmic reticulum (or microsomal compartment). For peptide drugs, the extent of hydrolysis by lumenal and membrane-bound peptidases reduces drug availability for intestinal absorption [56], Preferential hydrolysis (metabolic specificity) has been targeted for reconversion... 

Caslake MJ, Packard CJ, Gaw A, Murray E, Griffin BA, Vallance BD, et al. Fenofibrate and LDL metabolic heterogeneity in hypercholesterolemia. Arterios-cler Thromb 1993 13 702-711. 

Larsson, S. E. The metabolic heterogeneity of glycosaminoglycans of the different zones of the epiphyseal growth plate and the effect of ethane-l-hydroxy-l,l-diphosphonate (EHDP) upon glycosaminoglycan synthesis in vivo. Calc. Tiss. Res. 21, 67 (1976)... 

The majority of studies examining natural variability or experimental manipulation suggest the response to specific DOM components (known or presumed) is much stronger than the response to changes in bulk concentrations. These findings underscore the need to identify which components of DOM are generating the metabolic heterogeneity we observe in the real world. 

F5. Fainaru, M., Mahley, R. W., Hamilton, R. L., and Innerarity, T. L., Structural and metabolic heterogeneity of (J-very low density lipoproteins from cholesterol-fed dogs and from humans with Type III hyperlipoproteinemia. J. Lipid Res. 23, 702-714 (1982). 

Hepatocytes display metabolic heterogeneity according to their zonal location within the acinus. (42) (s. p. 24) Specific chemical processes thus proceed exclusively or predominantly in the hepatocytes of the periportal or the perivenous zones. The zonally segregated reactions may also be regulated separately. It seems that, under certain conditions, metabolic processes are also shifted from one zone of the acinus to another. 

Tab. 3.2 Morphological heterogeneity of liver cells and organelles as well as metabolic heterogeneity of hepatocytes according to their respective zonal location in the acinus (s. pp 23, 24)...

Cojocel C, Malta K, Pasino DA, Kuo, C-H, HookJ B. Metabolic heterogeneity of proximal and distal tubules. Life Sci 1983 33 855-861. 

K42. Kresse, H., Hddel, H., and Buddecke, E., Chemical and metabolic heterogeneity of a bovine aorta chondroitin sulfate-dermatan sulfote proteoglycan. Eut.. Biochem. 22, 557-562 (1971). 

The compositional and metabolic heterogeneity of operationally defined plasma lipoproteins necessitates the introduction of a classification system based on apolipoproteins as specific markers for identifying discrete lipoprotein families or particles. According to the chemical classification system, plasma lipoproteins consist of discrete simple and complex lipoproteins. Simple lipoproteins contain a single apolipoprotein, whereas complex lipoproteins contain two or more apolipoproteins. 

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