Pertussis toxin blocks activin A-induced production of inositol phosphates in rat hepatocytes.
The present study was conducted to examine an involvement of G protein in the action of activin A in rat parenchymal liver cells. Activin A induced a dose-dependent increase in inositol phosphates in cells prelabelled with [3H]inositol. The effect of activin A was completely blocked by pretreatment of the cells with pertussis toxin. In contrast, pertussis toxin had little effect on angiotensin II-induced production of inositol phosphates. Both activin A and angiotensin II inhibited glucagon-mediated production of cAMP. Pretreatment of the cells with pertussis toxin blocked the inhibition induced by both activin A and angiotensin II. In permeabilized cells, activin A augmented production of inositol phosphates. Activin-mediated production of inositol trisphosphate was enhanced by GTP-gamma S and was attenuated by GDP-beta S. These results suggest that a pertussis toxin-sensitive G protein(s) may be involved in the action of activin A in hepatocytes.
Mine
T
T
Fourth Department of Internal Medicine, University of Tokyo School of Medicine, Japan.
Kojima
I
I
Ogata
E
E
D028341:Activins; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D005934:Glucagon / Q000494:pharmacology; D006133:Growth Substances / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000494:pharmacology; D007265:Inhibins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007294:Inositol / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D051381:Rats; D014316:Tritium; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D006133:Growth Substances; D007295:Inositol Phosphates; D010566:Virulence Factors, Bordetella; D014316:Tritium; D028341:Activins; D000804:Angiotensin II; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D007294:Inositol; D007265:Inhibins; D005934:Glucagon; D000242:Cyclic AMP; D037342:Pertussis Toxin