G-proteins mediate inhibition and activation of Ca(2+)-induced exocytosis from SLO-permeabilized peptidergic nerve endings.
In SLO-permeabilized isolated nerve endings from the rat neurohypophysis, GTP, guanosine 5'[y-thio]triphosphate (GTPyS) and guanosine 5'(beta y-imido]triphosphate (GMPPNP) inhibit the Ca(2+)-evoked vasopressin release. Pretreatment with pertussis toxin enhances the inhibitory effects of both GTP-analogues. Omission of Mg2+ overcomes the effect of GMPPNP and reverses the inhibitory effect of GTP and GTPyS. In the absence of Mg2+, GTP and GTPyS now potentiate Ca(2+)-evoked secretion.
Ahnert-Hilger
G
G
Department of Internal Medicine, Universitätsklinikum Steglitz, Free University of Berlin, Germany.
Dayanithi
G
G
Spicher
K
K
Nordmann
J J
JJ
D000818:Animals; D001426:Bacterial Proteins; D002118:Calcium / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D009411:Nerve Endings / Q000187:drug effects / Q000502:physiology*; D010539:Permeability; D010904:Pituitary Gland, Posterior / Q000502:physiology; D051381:Rats; D013301:Streptolysins; D014667:Vasopressins / Q000378:metabolism
D001426:Bacterial Proteins; D013301:Streptolysins; C025964:streptolysin O; D014667:Vasopressins; D006165:Guanylyl Imidodiphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D008274:Magnesium; D002118:Calcium