Vasoactive peptides and phenylephrine actions in isolated teleost hepatocytes.
The metabolic actions of the vasoactive peptides vasotocin and isotocin and the alpha-agonist phenylephrine are examined in hepatocytes isolated from three teleost species: brown bullhead, rainbow trout, and American eel. These three compounds influenced hepatic gluconeogenesis and glycogenolysis with significant species differences. Vasotocin and isotocin affected only eel hepatocytes activating gluconeogenesis by 1.7-fold and glycogenolysis by 3-fold. Phenylephrine increased glycogenolysis by 7-fold in bullhead hepatocytes and gluconeogenesis by 1.4-fold in trout cells. Vasotocin and phenylephrine actions were correlated with increases in adenosine 3',5'-cyclic monophosphate (cAMP). The vasotocin effects were unaffected by beta- and alpha-antagonists supporting a V2-type receptor on eel hepatocytes. Phenylephrine effects were abolished by propranolol and reduced by prazosin and yohimbine (alpha 1- and alpha 2-antagonists, respectively). Phenylephrine, therefore, affected fish hepatocyte metabolism either by a mixed alpha/beta-receptor mechanism emphasizing beta-adrenoceptors or the classic alpha/beta agonist/antagonist scheme defined for mammals is not appropriate for these fish preparations.
Moon
T W
TW
Department of Biology, University of Ottawa, Ontario, Canada.
Mommsen
T P
TP
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000811:Anguilla; D000818:Animals; D002478:Cells, Cultured; D005943:Gluconeogenesis / Q000187:drug effects*; D007059:Ictaluridae; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D014337:Trout; D014667:Vasopressins / Q000494:pharmacology*; D014668:Vasotocin / Q000494:pharmacology*; D015016:Yohimbine / Q000494:pharmacology
D008112:Liver Glycogen; D014667:Vasopressins; D010656:Phenylephrine; D015016:Yohimbine; D010121:Oxytocin; C008215:isotocin; D011433:Propranolol; D015056:1-Methyl-3-isobutylxanthine; D014668:Vasotocin; D011224:Prazosin