title: Abnormal epithelial transport in cystic fibrosis jejunum.
abstract: Abnormal epithelial electrolyte transport has been identified in a range of cystic fibrosis (CF) organs and appears to account for the various clinical manifestations of the disease. The aim of this study was to further define the Cl- secretion defect in CF jejunum. Excised jejunum was obtained from 11 CF patients and 12 controls. Transport studies were performed on stripped epithelium in vitro under short-circuited conditions in Ussing Chambers. 3-Isobutyl-1-methylxanthine (IBMX) (300 microM) significantly increased Cl- secretion in control (-2.3 +/- 0.6 to -3.3 +/- 0.7 mueq.cm-2.h-1; P less than 0.01, paired t test; n = 5 subjects) but not in CF jejunum (-0.5 +/- 0.3 to -0.1 +/- 0.4; n = 4). However in contrast to control jejunum, net Na+ absorption in CF jejunum was higher in the IBMX (1.3 +/- 0.5 mueq.cm-2.h-1) compared with basal periods (0.6 +/- 0.3; P less than 0.05, paired t test). IBMX stimulation of tissue adenosine 3',5'-cyclic monophosphate (cAMP) was similar in both control and CF jejunum. A range of secretagogues known to induce secretion in mammalian intestine, including dibutyryl cAMP (DBcAMP), DBcGMP, Ca2+ ionophore A23187, and the protein kinase C activator 4 beta-phorbol 12,13-dibutyrate, failed to induce secretion in CF jejunum. In conclusion, CF jejunum failed to exhibit Cl- secretion and also demonstrated abnormalities of Na+ absorption. These results support the view that the defect lies at a site distal to the intracellular messengers. Moreover, these abnormalities of intestinal electrolyte transport may account for some of the gastrointestinal manifestations of the disease such as meconium ileus and distal intestinal obstruction syndrome.
authors.affiliation: Department of Pediatrics, Children's Hospital, Camperdown, Australia.
authors.forename: E V
authors.initials: EV
authors.lastname: O'Loughlin
authors.forename: D M
authors.initials: DM
authors.lastname: Hunt
authors.forename: K J
authors.initials: KJ
authors.lastname: Gaskin
authors.forename: D
authors.initials: D
authors.lastname: Stiel
authors.forename: I M
authors.initials: IM
authors.lastname: Bruzuszcak
authors.forename: H C
authors.initials: HC
authors.lastname: Martin
authors.forename: C
authors.initials: C
authors.lastname: Bambach
authors.forename: R
authors.initials: R
authors.lastname: Smith
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000368:Aged; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002648:Child; D000242:Cyclic AMP / Q000502:physiology; D003550:Cystic Fibrosis / Q000503:physiopathology*; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D007477:Ions; D007583:Jejunum / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*; D007700:Kinetics; D008875:Middle Aged; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D012016:Reference Values
chemical_list: D007477:Ions; D003995:Dibutyryl Cyclic GMP; D015240:Phorbol 12,13-Dibutyrate; D000001:Calcimycin; D003994:Bucladesine; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine