title: Transient up-regulation of P-glycoprotein reduces tacrolimus absorption after ischemia-reperfusion injury in rat ileum.
abstract: Ischemia-reperfusion injury is an unavoidable problem for organ transplantation including small bowel transplantation, and causes a large intra-individual variation of tacrolimus (FK506) pharmacokinetics. Little information is available about the regulation of the intestinal P-glycoprotein expression during tissue regeneration. In the present study, we have examined the molecular and functional variations of ileum P-glycoprotein using rats after ischemia-reperfusion treatment. Morphological study revealed a rapid regeneration of the intestinal wall during 24 h after reperfusion. A reverse transcription-coupled competitive PCR and Western blot analysis revealed that the intestinal expression of P-glycoprotein recovered with time after reperfusion. At 24 h after reperfusion, the ileum P-glycoprotein level was transiently increased to two-fold, and the absorption rate of dihydro-[(3)H]FK506 from in situ ileum loop into portal vein was markedly low in comparison with the control. P-glycoprotein was detected in the crypt area as well as in villous cells at 6 h after reperfusion, and then localized to the apical surface at 24 h consistent with the cell proliferation and differentiation. However, the P-glycoprotein level returned to normal at 48 h. The intra-individual variation in the absorptive rate of tacrolimus was suggested to be regulated by the morphological status of the intestinal epithelium and enterocyte expression level of P-glycoprotein. Therefore, the monitoring of the enterocyte P-glycoprotein level would provide useful information for determining the dosage of tacrolimus immediately after small bowl transplantation.
authors.affiliation: Department of Pharmacy, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Omae
authors.forename: Maki
authors.initials: M
authors.lastname: Goto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shimomura
authors.forename: Satohiro
authors.initials: S
authors.lastname: Masuda
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Ito
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okuda
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Inui
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D000818:Animals; D001485:Basement Membrane / Q000737:chemistry; D001692:Biological Transport; D007082:Ileum / Q000098:blood supply* / Q000737:chemistry / Q000378:metabolism; D007150:Immunohistochemistry; D007166:Immunosuppressive Agents / Q000493:pharmacokinetics*; D007408:Intestinal Absorption; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000378:metabolism*; D016559:Tacrolimus / Q000493:pharmacokinetics*; D015854:Up-Regulation
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D016559:Tacrolimus