No major effects of vitamin D3 (1,25 dihydroxyvitamin D3) on absorption and pharmacokinetics of folic acid and fexofenadine in healthy volunteers.

Purpose: In Caco-2 cells, folate uptake via the proton-coupled folate transporter (PCFT) increases significantly by a 3-day treatment with 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Additionally, mRNA content and protein expression of the transporter OATP1A2 were increased up to ninefold with 1,25(OH)2D3. We investigated whether these in vitro findings can be confirmed in humans in vivo.

ABC-transporters are localized in caveolin-1-positive and reggie-1-negative and reggie-2-negative microdomains of the canalicular membrane in rat hepatocytes.

Unlabelled: The canalicular plasma membrane is constantly exposed to bile acids acting as detergents. Bile acids are essential to mediate release of biliary lipids from the canalicular membrane. Membrane microdomains (previously called lipid rafts) are biochemically defined by their resistance to detergent solubilization at cold temperature.

Tegaserod inhibits the serotonin transporter SERT.

Background: Tegaserod is a novel drug for the treatment of constipation-predominant irritable bowel syndrome. Tegaserod is thought to exert its prokinetic effect as a selective partial agonist of serotonin receptor type 4 (5-HT4) receptors located in the enteric nervous system. It is unknown, however, whether tegaserod interacts with the human serotonin reuptake transporter (hSERT) and the uptake transporters for dopamine (hDAT) and norepinephrine (hNET).

hPepT1 selectively transports muramyl dipeptide but not Nod1-activating muramyl peptides.

Muramyl peptides derived from bacterial peptidoglycan are detected intracellularly by Nod1 and Nod2, 2 members of the newly characterized nod-like receptor (NLR) family of pattern recognition molecules. In the absence of bacterial invasion into the host cytosolic compartment, it remains unclear whether muramyl peptides can cross the plasma membrane and localize into the cytosol. We have recently demonstrated that the plasma membrane transporter, hPepT1, was able to efficiently translocate muramyl dipeptide (MDP), a specific Nod2-activating molecule, into host cells.

Regional distribution of solute carrier mRNA expression along the human intestinal tract.

Intestinal absorption of drugs, nutrients, and other compounds is mediated by uptake transporters expressed at the apical enterocyte membrane. These compounds are returned to the intestinal lumen or released into portal circulation by intestinal efflux transporters expressed at apical or basolateral membranes, respectively. One important transporter superfamily, multiple members of which are intestinally expressed, are the solute carriers (SLCs).

Localization of organic anion transporting polypeptides in the rat and human ciliary body epithelium.

Purpose: To identify and localize the expression of multispecific organic anion transporting polypeptides (Oatps/OATPs) in the ciliary body epithelium and to investigate their possible involvement in the transport of the antiglaucoma agent unoprostone.

Methods: Oatps/OATPs were detected by immunoblot analysis and by immunofluorescence microscopy in homogenized and fixed rat and human ciliary body samples using specific polyclonal antibodies. Transport of 3H-labelled unoprostone was measured in Oatp/OATP expressing Xenopus laevis oocytes.

Interactions of glycyrrhizin with organic anion transporting polypeptides of rat and human liver.

Glycyrrhizin (GL) is used in Japan for the treatment of chronic hepatitis C. Following intravenous administration, GL is eliminated mainly by excretion into bile. Hepatocyte uptake of GL is a carrier-mediated process with characteristics resembling the organic anion transporting polypeptides (OATPs, solute carrier gene family SLC21A).