title: Methylprednisolone accelerates the ontogeny of sodium-taurocholate cotransport in rat ileal brush border membranes.
abstract: The effect of methylprednisolone on the postnatal maturation of taurocholate transport was studied by using isolated ileal brush border membrane vesicles. Vesicles were prepared from 14-day-old control, 14-day-old methylprednisolone-treated, and untreated 21-day-old rats. Methylprednisolone treatment resulted in a significant stimulation of taurocholate uptake by an inwardly directed Na+ gradient when compared with a choline gradient incubation. These differences occurred at 20 seconds and 1, 2, and 5 minutes of incubation (P less than 0.05). In 14-day-old controls, uptake was similar for Na+ and choline gradients. A plot of active uptake velocity vs. taurocholate concentration (0.1 to 1.0 mmol/L) in 14-day-old controls was linear and approached the abscissa, indicating the absence of active transport. Plots for methylprednisolone-treated rats showed saturability. An inwardly directed Na+ gradient stimulated initial taurocholate uptake rates by twofold at 37 degrees C (P less than 0.01), but not at 4 degrees C. Glycocholate and glycodeoxycholate inhibited Na+-stimulated taurocholate uptake by 50% (P less than 0.01) and 20% (P less than 0.05), respectively. These data indicate that pharmacologic doses of methylprednisolone accelerate the postnatal acquisition of Na+-dependent taurocholate cotransport in rat ileal brush border membranes.
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D001692:Biological Transport; D002794:Choline / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D007082:Ileum / Q000254:growth & development / Q000648:ultrastructure*; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000378:metabolism; D008775:Methylprednisolone / Q000494:pharmacology*; D008871:Microvilli / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013656:Taurocholic Acid / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D013656:Taurocholic Acid; D012964:Sodium; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; D007931:Leucyl Aminopeptidase; D000254:Sodium-Potassium-Exchanging ATPase; D002794:Choline; D008775:Methylprednisolone