Mechanisms for the stimulatory and inhibitory effects of carbamoylcholine on canine gastric D-cells.
We have previously reported that carbamoylcholine (carbachol), a recognized inhibitor of somatostatin release from D-cells, can act as stimulant following pretreatment of cells with pertussis toxin. In the present studies we have observed that pertussis toxin reverses the inhibitory effects of carbachol on D-cell stimulated with either cAMP or 12-O-tetradecanoyl-phorbol 13-acetate. Furthermore, the stimulatory effects of carbachol on D-cells pretreated with pertussis toxin potentiated the actions of pentagastrin without further enhancing the release of 3H-inositol triphosphate from prelabeled cells. These studies suggest that carbachol exerts its inhibitory effects on D-cells via pertussis toxin sensitive guanine nucleotide binding proteins at a point distal to the activation of different signal transduction mechanisms and that the stimulatory effects of carbachol are mediated by mechanisms that are independent of membrane phosphoinositide turnover.
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology; D004285:Dogs; D019204:GTP-Binding Proteins / Q000502:physiology; D005753:Gastric Mucosa / Q000187:drug effects / Q000502:physiology*; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000502:physiology; D012636:Secretory Rate / Q000187:drug effects; D013004:Somatostatin / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D010716:Phosphatidylinositols; D011976:Receptors, Muscarinic; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D013004:Somatostatin; D003994:Bucladesine; D002217:Carbachol; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate