Effects of cyclosporin A on paracellular and transcellular transport of horseradish peroxidase in perfused rat livers.

摘要: The immunosuppressive agent cyclosporin A (CsA)is known to cause cholestasis. Transcellular andparacellular transport of macromolecules contribute,albeit a minor extent, bile formation, but little is about the effects CsA on thesepathways. aims this study were investigate theinfluence tight junction (paracellular)permeability and transcytotic vesicular pathways labeled with horseradish peroxidase (HRP) inperfused rat liver. Livers from male Sprague-Dawley ratswere perfused Krebs-Henseleit buffer (albumin 1%,RBC 20%, amino acid mixture). Taurodehydrocholate (1 μM/min) was coinfused into portalvein; 1 μg/ml CsA, dissolved in Cremophor-EL (CsAlivers), or vehicle alone (CEL livers), added tothe medium. Tight permeability assessed by administering HRP (25 mg) as short pulseto livers, operating under single-passconditions. Under such conditions, output thebile shows two components: an initial peak atapproximately 3-5 min, corresponding paracellular transferacross junctions, second 15 vesiculartransport. Furthermore, we vesiculartransport pathway examining HRPlabeled vesicles theperisinusoidal (PS) pericanalicular (PC) areas usingultrastructural morphometric analysis. To analyze inhepatocytes rapid late pathways, 1-min pulseof high dose (500 200 mg, respectively) wasgiven. Two 18 min after single-pass perfusion thelivers fixed 2.5% glutaraldehyde- 0.8% paraformaldehyde 0.1 mM cacodylatebuffer, pH 7.8. total area, theHRP-containing structures, quantifiedmorphometrically liver samples. At concentrations of1.2 μg/ml, produced twofold increase theparacellular transfer bile. underthe (transcellular pathway) thebiliary secretion curve similar CEL- CsA-treated livers. Morphometric analysisconfirmed that treatment did not affect thepercentage area HRP-labeled either thepericanalicular perisinusoidal at 2 min(rapid (late pathway). Theseresults indicate increases junctionalpermeability whereas it does inhibit latetranscytotic vesicle pathways.