title: Mobilization of the hormone-sensitive calcium pool increases hepatocyte tight junctional permeability in the perfused rat liver.
abstract: Hepatocyte tight junctional permeability has been shown to be regulated by hormones that exert their effects via phospholipase C activation. However, the precise transduction pathway involved in this effect is not known. The present study has employed the selective inhibitor of microsomal Ca2+ sequestration, 2,5-di(tert-butyl)-1,4-benzohydroquinone (tBuBHQ), to examine the effect of the mobilization of the endoplasmic reticular Ca2+ pool on tight junctional permeability in the perfused rat liver. Infusion of tBuBHQ followed by a bolus infusion of horseradish peroxidase (HRP) resulted in a significant increase in the first peak of biliary HRP, a measure of junctional permeability, whereas transcellular (vesicular) transport of HRP was not affected. Therefore, we conclude that the effect of hormones on tight junctional permeability is mediated, at least in part, by the mobilization of intracellular Ca2+.
authors.affiliation: Department of Toxicology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Llopis
authors.forename: G E
authors.initials: GE
authors.lastname: Kass
authors.forename: S K
authors.initials: SK
authors.lastname: Duddy
authors.forename: G C
authors.initials: GC
authors.lastname: Farell
authors.forename: A
authors.initials: A
authors.lastname: Gahm
authors.forename: S
authors.initials: S
authors.lastname: Orrenius
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects; D006728:Hormones / Q000494:pharmacology*; D006735:Horseradish Peroxidase / Q000494:pharmacology; D006873:Hydroquinones / Q000494:pharmacology*; D007260:Infusion Pumps; D007365:Intercellular Junctions / Q000187:drug effects*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012680:Sensitivity and Specificity
chemical_list: D006728:Hormones; D006873:Hydroquinones; C019359:2,5-di-tert-butylhydroquinone; D006735:Horseradish Peroxidase; D002118:Calcium