title: Alteration with dietary state of the activity and zonal distribution of adenylate cyclase stimulated by glucagon, fluoride and forskolin in microdissected rat liver tissue.
abstract: Adenylate cyclase activated by glucagon, fluoride and forskolin was measured in liver homogenates and microdissected periportal and perivenous tissue of fed and fasted rats. A radiochemical microtest, more sensitive by 2-3 orders of magnitude as compared with the usual assay, was established for the determination of the activity in liver samples corresponding to 200-600 ng dry weight. In liver homogenates from fasted as compared to fed animals the glucagon-stimulated and fluoride-stimulated activity was increased by 1.65-fold, while the basal and the forskolin-stimulated activity remained the same. In microdissected tissue of both fed and fasted animals the activity was stimulated in about 60% of the samples by glucagon, fluoride and forskolin (responsive samples). However, in about 40% of the microdissected tissue samples the activity could not be stimulated by any of the above activators (non-responsive samples). In responsive microdissected tissue of fasted as compared to fed animals, the glucagon-stimulated and fluoride stimulated activity but not the basal and the forskolin-activated activity was increased by 2-3-fold. In responsive microdissected samples of fed animals neither the basal nor the stimulated activities showed a significant periportal to perivenous gradient. In samples of fasted animals, however, a zonal gradient was observed for the glucagon-stimulated activity exhibiting a 1.5-fold higher rate in the perivenous zone.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D005576:Colforsin; D004032:Diet; D004210:Dissection / Q000379:methods; D004224:Diterpenes / Q000494:pharmacology*; D005215:Fasting; D005459:Fluorides / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology*; D006651:Histocytochemistry / Q000379:methods; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004224:Diterpenes; D005576:Colforsin; D005934:Glucagon; D000262:Adenylyl Cyclases; D005459:Fluorides