Basolateral cell membrane

Golgi Apparatus intercellular Space Nucleus Basolateral Cell Membrane... 

The successful application of in vitro models of intestinal drug absorption depends on the ability of the in vitro model to mimic the relevant characteristics of the in vivo biological barrier. Most compounds are absorbed by passive transcellular diffusion. To undergo tran-scellular transport a molecule must cross the lipid bilayer of the apical and basolateral cell membranes. In recent years, there has been a widespread acceptance of a technique, artificial membrane permeation assay (PAMPA), to estimate intestinal permeability.117118 The principle of the PAMPA is that, diffusion across a lipid layer, mimics transepithelial permeation. Experiments are conducted by applying a drug solution on top of a lipid layer covering a filter that separates top (donor) and bottom (receiver) chambers. The rate of drug appearance in the bottom wells should reflect the diffusion across the lipid layer, and by extrapolation, across the epithelial cell layer. 

Principal and intercalated cells of the collecting ducts. Principal (top) cells reabsorb Na+ and the secreted K+. Na+ entry across apical cell membranes is mediated by a Na+ channel. Na+ exit across basolateral cell membranes is effected by the NaVK+-ATPase, shown by the filled circle in the principal cell. The rates of Na+ reabsorption and K+ secretion are regulated by aldosterone. Intercalated (bottom) cells reabsorb K+ and HCOa and secretes H+. K+ entry and H+secretion are mediated by an H+/K ATPase, which is shown by the filled circle in the apical cell membrane of the intercalated cell. 

Figure9.6 Secondary active Na cotransport system in an apical cell membrane, which is driven by the Na /K -ATPase in the basolateral cell membrane.

Figure 9.7 Intestinal peptide transport. Peptides are taken upinto enterocytes together with H+ ions. The proton gradient is maintained via an Na + /H+ antiport system in the apical cell membrane. The Na+ gradient is guaranteed by the Na + /I<+-ATPase in the basolateral cell membrane.

Cephaloridine-induced nephrotoxicity is not restricted to the S2 segment but also involves the S3 segment of the proximal tubule [86]. More recent studies suggest that the rat renal organic anion transporter 1 (OATl) located in the renal basolateral cell membrane. 

NIS is located in the basolateral cell membranes of both the oxyntic and the pyloric portions of the gastric mucosa in rat, as well as in man (Josefsson et al., 2002 Vayre et ai, 1999). In the rumen parsproventricularis) of rat and mouse no NIS was found (Josefsson et al., 2002), which is not surprising considering that this part of the rodent stomach is lined by squamous epithelium and not gastric... 

Figure 22.3 Gastric NIS in rat fetus. Section of oxyntic mucosa from a rat fetus at E19 stained by immunohistochemistry with a polyclonal antiserum raised against the eight C-terminal amino acids of rat-NIS. The site of the antigen-antibody reaction was revealed by FITC-labeled pig anti-rabbit IgG. Staining is intense in the basolateral cell membranes of the epithelial surface cells. Magnification x200.

NIS is located in the basolateral cell membrane of the gastric mucosal surface cells. 

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