title: Morphometrical analysis of the gap-junctional area in parenchymal cells of the rat liver after administration of dibutyryl cAMP and aminophylline.
abstract: In view of the presumed involvement of gap junctions in the coordination of metabolic activities, the influence of cAMP as a regulatory signal of cell metabolism on gap junctions of hepatocytes has been examined. Male rats received two intraperitoneal doses of 10 mg dibutyryl cAMP/100 g body weight with a time interval of 2.5 h and were decapitated 2.5 h later. After this 5-h interval, analysis of freeze-fracture replicas of fixed liver tissue revealed an increase in the mean (+/- SEM) gap-junctional membrane portion on the lateral hepatocyte membranes from 0.049 +/- 0.003 (n = 66) in controls to 0.061 +/- 0.003 (n = 70) in treated rats, while the configuration of the connexons appeared unaltered. This effect could not be reinforced by prior administration of aminophylline: the relative gap-junctional area is similarly extended from 0.054 +/- 0.003 (n = 126) in the control group to 0.065 +/- 0.004 (n = 105) in the experimental animals. Probing for the time course of the junctional response, a group of rats was sacrificed 3 h after the onset of treatment. Already within this time, the gap-junctional area is augmented from 0.042 +/- 0.004 (n = 63) in the concurrent controls to 0.069 +/- 0.006 (n = 42) in the treated rats. These statistically significant increases in area may suggest a stimulating effect of cAMP on gap junctions of hepatocytes in vivo.
authors.affiliation: Institute of Histology and Microscopic Anatomy, University of Antwerp, Belgium.
authors.forename: A M
authors.initials: AM
authors.lastname: De Mazière
authors.forename: D W
authors.initials: DW
authors.lastname: Scheuermann
mesh_terms: D000628:Aminophylline / Q000494:pharmacology*; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D005614:Freeze Fracturing; D007365:Intercellular Junctions / Q000187:drug effects / Q000648:ultrastructure*; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D008854:Microscopy, Electron; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
chemical_list: D000628:Aminophylline; D003994:Bucladesine