Pertussis toxin does not inhibit alpha 1-adrenergic potentiation of beta-adrenergic stimulation of cyclic AMP accumulation in rat pinealocytes.
The hypothesis that Gi might be involved in the alpha 1-adrenergic, protein kinase C (PKC)-mediated amplification of beta-adrenergic cyclic AMP stimulation in rat pinealocytes was investigated. Treatment of pinealocytes with a high concentration of pertussis toxin (500 ng/ml, 18 h) almost completely (approximately 95%) inactivated two cell membrane G-proteins (kDa 40.7 and 39.8) judged by back ADP-ribosylation of pinealocyte membrane proteins. However, this treatment failed to inhibit either the beta-adrenergic (isoprenaline, ISO 10(-6) M), alpha 1-plus beta-adrenergic (noradrenaline, NA 10(-5) M) or beta-adrenergic plus 12-O-tetradecanoylphorbol 13-acetate (TPA 10(-7) M) induced stimulation of cyclic AMP or cyclic GMP. These results suggest that alpha 1-adrenergic potentiation of beta-adrenergic stimulation of cyclic AMP and cyclic GMP does not involve a pertussis toxin-sensitive G-protein.
Sugden
D
D
Biomedical Sciences Division, King's College London, U.K.
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D037342:Pertussis Toxin; D010870:Pineal Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D007545:Isoproterenol; D009638:Norepinephrine